SQL - Bun

Queries are written as tagged template literals, and the client supports connection pooling, transactions, and prepared statements.

db.ts

import { sql, SQL } from "bun";

// PostgreSQL (default)
const users = await sql`
  SELECT * FROM users
  WHERE active = ${true}
  LIMIT ${10}
`;

// With MySQL
const mysql = new SQL("mysql://user:pass@localhost:3306/mydb");
const mysqlResults = await mysql`
  SELECT * FROM users 
  WHERE active = ${true}
`;

// With SQLite
const sqlite = new SQL("sqlite://myapp.db");
const sqliteResults = await sqlite`
  SELECT * FROM users 
  WHERE active = ${1}
`;

Features

Tagged template literals to protect against SQL injection
Transactions
Named & positional parameters
Connection pooling
BigInt support
SASL (SCRAM-SHA-256), MD5, and Clear Text authentication
Connection timeouts
Returning rows as data objects, arrays of arrays, or Buffer
Binary protocol support makes it faster
TLS support (and auth mode)
Automatic configuration with environment variables

Database Support

Bun.SQL provides a unified API for multiple database systems:

PostgreSQL

PostgreSQL is used when:

The connection string doesn’t match SQLite or MySQL patterns (it’s the fallback adapter)
The connection string explicitly uses postgres:// or postgresql:// protocols
No connection string is provided and environment variables point to PostgreSQL

db.ts

import { sql } from "bun";
// Uses PostgreSQL if DATABASE_URL is not set or is a PostgreSQL URL
await sql`SELECT ...`;

import { SQL } from "bun";
const pg = new SQL("postgres://user:pass@localhost:5432/mydb");
await pg`SELECT ...`;

MySQL

MySQL support is built into Bun.SQL, with the same tagged template literal interface, and is compatible with MySQL 5.7+ and MySQL 8.0+:

db.ts

import { SQL } from "bun";

// MySQL connection
const mysql = new SQL("mysql://user:password@localhost:3306/database");
const mysql2 = new SQL("mysql2://user:password@localhost:3306/database"); // mysql2 protocol also works

// Using options object
const mysql3 = new SQL({
  adapter: "mysql",
  hostname: "localhost",
  port: 3306,
  database: "myapp",
  username: "dbuser",
  password: "secretpass",
});

// Works with parameters - automatically uses prepared statements
const users = await mysql`SELECT * FROM users WHERE id = ${userId}`;

// Transactions work the same as PostgreSQL
await mysql.begin(async tx => {
  await tx`INSERT INTO users (name) VALUES (${"Alice"})`;
  await tx`UPDATE accounts SET balance = balance - 100 WHERE user_id = ${userId}`;
});

// Bulk inserts
const newUsers = [
  { name: "Alice", email: "alice@example.com" },
  { name: "Bob", email: "bob@example.com" },
];
await mysql`INSERT INTO users ${mysql(newUsers)}`;

MySQL Connection String Formats

MySQL accepts various URL formats for connection strings:

// Standard mysql:// protocol
new SQL("mysql://user:pass@localhost:3306/database");
new SQL("mysql://user:pass@localhost/database"); // Default port 3306

// mysql2:// protocol (compatibility with mysql2 npm package)
new SQL("mysql2://user:pass@localhost:3306/database");

// With query parameters
new SQL("mysql://user:pass@localhost/db?ssl=true");

// Unix socket connection
new SQL("mysql://user:pass@/database?socket=/var/run/mysqld/mysqld.sock");

MySQL-Specific Features

MySQL databases support:

Prepared statements: Automatically created for parameterized queries with statement caching
Binary protocol: For better performance with prepared statements and accurate type handling
Multiple result sets: Support for stored procedures returning multiple result sets
Authentication plugins: Support for mysql_native_password, caching_sha2_password (MySQL 8.0 default), and sha256_password
SSL/TLS connections: Configurable SSL modes similar to PostgreSQL
Connection attributes: Client information sent to server for monitoring
Query pipelining: Execute multiple prepared statements without waiting for responses

SQLite

SQLite support is built into Bun.SQL, with the same tagged template literal interface:

import { SQL } from "bun";

// In-memory database
const memory = new SQL(":memory:");
const memory2 = new SQL("sqlite://:memory:");

// File-based database
const sql1 = new SQL("sqlite://myapp.db");

// Using options object
const sql2 = new SQL({
  adapter: "sqlite",
  filename: "./data/app.db",
});

// For simple filenames, specify adapter explicitly
const sql3 = new SQL("myapp.db", { adapter: "sqlite" });

SQLite Connection String Formats

SQLite accepts various URL formats for connection strings:

// Standard sqlite:// protocol
new SQL("sqlite://path/to/database.db");
new SQL("sqlite:path/to/database.db"); // Without slashes

// file:// protocol (also recognized as SQLite)
new SQL("file://path/to/database.db");
new SQL("file:path/to/database.db");

// Special :memory: database
new SQL(":memory:");
new SQL("sqlite://:memory:");
new SQL("file://:memory:");

// Relative and absolute paths
new SQL("sqlite://./local.db"); // Relative to current directory
new SQL("sqlite://../parent/db.db"); // Parent directory
new SQL("sqlite:///absolute/path.db"); // Absolute path

// With query parameters
new SQL("sqlite://data.db?mode=ro"); // Read-only mode
new SQL("sqlite://data.db?mode=rw"); // Read-write mode (no create)
new SQL("sqlite://data.db?mode=rwc"); // Read-write-create mode (default)

Simple filenames without a protocol (like "myapp.db") require explicitly specifying { adapter: "sqlite" } to avoid ambiguity with PostgreSQL.

SQLite-Specific Options

SQLite databases support additional configuration options:

const sql = new SQL({
  adapter: "sqlite",
  filename: "app.db",

  // SQLite-specific options
  readonly: false, // Open in read-only mode
  create: true, // Create database if it doesn't exist
  readwrite: true, // Open for reading and writing

  // Additional Bun:sqlite options
  strict: true, // Enable strict mode
  safeIntegers: false, // Use JavaScript numbers for integers
});

Query parameters in the URL are parsed to set these options:

?mode=ro → readonly: true
?mode=rw → readonly: false, create: false
?mode=rwc → readonly: false, create: true (default)

Inserting data

Pass JavaScript values directly to the SQL template literal; Bun handles the escaping.

import { sql } from "bun";

// Basic insert with direct values
const [user] = await sql`
  INSERT INTO users (name, email) 
  VALUES (${name}, ${email})
  RETURNING *
`;

// Using object helper for cleaner syntax
const userData = {
  name: "Alice",
  email: "alice@example.com",
};

const [newUser] = await sql`
  INSERT INTO users ${sql(userData)}
  RETURNING *
`;
// Expands to: INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com')

Bulk Insert

You can also pass an array of objects, which Bun expands into an INSERT INTO ... VALUES ... statement.

const users = [
  { name: "Alice", email: "alice@example.com" },
  { name: "Bob", email: "bob@example.com" },
  { name: "Charlie", email: "charlie@example.com" },
];

await sql`INSERT INTO users ${sql(users)}`;

Picking columns to insert

Use sql(object, ...string) to pick which columns to insert. Each column must be defined on the object.

const user = {
  name: "Alice",
  email: "alice@example.com",
  age: 25,
};

await sql`INSERT INTO users ${sql(user, "name", "email")}`;
// Only inserts name and email columns, ignoring other fields

Query Results

By default, Bun’s SQL client returns query results as arrays of objects, where each object represents a row with column names as keys. Two other formats are available.

sql``.values() format

The sql``.values() method returns each row as an array of values, in the same order as the columns in your query.

const rows = await sql`SELECT * FROM users`.values();
console.log(rows);

The rows look like:

[
  ["Alice", "alice@example.com"],
  ["Bob", "bob@example.com"],
];

sql``.values() is useful when a query returns duplicate column names. With objects (the default), the last column wins because the column name is the key. With sql``.values(), every column is present in the array, so you can read duplicates by index.

sql``.raw() format

The .raw() method returns rows as arrays of Buffer objects. Use it for binary data or for performance.

const rows = await sql`SELECT * FROM users`.raw();
console.log(rows); // [[Buffer, Buffer], [Buffer, Buffer], [Buffer, Buffer]]

SQL Fragments

Bun can build queries dynamically from runtime conditions without risking SQL injection.

Dynamic Table Names

To reference tables or schemas dynamically, use the sql() helper, which escapes them:

// Safely reference tables dynamically
await sql`SELECT * FROM ${sql("users")}`;

// With schema qualification
await sql`SELECT * FROM ${sql("public.users")}`;

Conditional Queries

Use the sql() helper to build queries with conditional clauses:

// Optional WHERE clauses
const filterAge = true;
const minAge = 21;
const ageFilter = sql`AND age > ${minAge}`;
await sql`
  SELECT * FROM users
  WHERE active = ${true}
  ${filterAge ? ageFilter : sql``}
`;

Dynamic columns in updates

Use sql(object, ...string) to pick which columns to update. Each column must be defined on the object. If you don’t list any columns, all keys on the object are used.

await sql`UPDATE users SET ${sql(user, "name", "email")} WHERE id = ${user.id}`;
// uses all keys from the object to update the row
await sql`UPDATE users SET ${sql(user)} WHERE id = ${user.id}`;

Dynamic values and `where in`

Value lists can also be created dynamically, for WHERE IN queries. You can also pass an array of objects and name the key to build the list from.

await sql`SELECT * FROM users WHERE id IN ${sql([1, 2, 3])}`;

const users = [
  { id: 1, name: "Alice" },
  { id: 2, name: "Bob" },
  { id: 3, name: "Charlie" },
];
await sql`SELECT * FROM users WHERE id IN ${sql(users, "id")}`;

`sql.array` helper

The sql.array helper creates PostgreSQL array literals from JavaScript arrays:

// Create array literals for PostgreSQL
await sql`INSERT INTO tags (items) VALUES (${sql.array(["red", "blue", "green"])})`;
// Generates: INSERT INTO tags (items) VALUES (ARRAY['red', 'blue', 'green'])

// Works with numeric arrays too
await sql`SELECT * FROM products WHERE ids = ANY(${sql.array([1, 2, 3])})`;
// Generates: SELECT * FROM products WHERE ids = ANY(ARRAY[1, 2, 3])

sql.array is PostgreSQL-only. Multi-dimensional arrays and NULL elements may not be supported yet.

sql``.simple()

The PostgreSQL wire protocol supports two types of queries: “simple” and “extended”. Simple queries can contain multiple statements but don’t support parameters, while extended queries (the default) support parameters but only allow one statement. To run multiple statements in a single query, use sql``.simple():

// Multiple statements in one query
await sql`
  SELECT 1;
  SELECT 2;
`.simple();

Simple queries are useful for database migrations and setup scripts. Simple queries cannot use parameters (${value}). If you need parameters, split your query into separate statements.

Queries in files

sql.file reads a query from a file and executes it. If the file uses placeholders like $1 and $2, you can pass parameters to the query. Without parameters, the file can contain multiple commands.

const result = await sql.file("query.sql", [1, 2, 3]);

Unsafe Queries

sql.unsafe executes raw SQL strings. Use it with caution: it does not escape user input. Without parameters, the string can contain more than one command.

// Multiple commands without parameters
const result = await sql.unsafe(`
  SELECT ${userColumns} FROM users;
  SELECT ${accountColumns} FROM accounts;
`);

// Using parameters (only one command is allowed)
const result = await sql.unsafe("SELECT " + dangerous + " FROM users WHERE id = $1", [id]);

Execute and Cancelling Queries

Queries are lazy: they only start executing when awaited or run with .execute(). To cancel a running query, call cancel() on the query object.

const query = sql`SELECT * FROM users`.execute();
setTimeout(() => query.cancel(), 100);
await query;

Database Environment Variables

You can configure sql connection parameters with environment variables. The client checks them in order of precedence and detects the database type from the connection string format.

Automatic Database Detection

When you use Bun.sql() without arguments, or new SQL() with a connection string, Bun detects the adapter from the URL format:

MySQL Auto-Detection

MySQL is selected when the connection string matches these patterns:

mysql://... - MySQL protocol URLs
mysql2://... - MySQL2 protocol URLs (compatibility alias)

// These all use MySQL automatically (no adapter needed)
const sql1 = new SQL("mysql://user:pass@localhost/mydb");
const sql2 = new SQL("mysql2://user:pass@localhost:3306/mydb");

// Works with DATABASE_URL environment variable
DATABASE_URL="mysql://user:pass@localhost/mydb" bun run app.js
DATABASE_URL="mysql2://user:pass@localhost:3306/mydb" bun run app.js

SQLite Auto-Detection

SQLite is selected when the connection string matches these patterns:

:memory: - In-memory database
sqlite://... - SQLite protocol URLs
sqlite:... - SQLite protocol without slashes
file://... - File protocol URLs
file:... - File protocol without slashes

// These all use SQLite automatically (no adapter needed)
const sql1 = new SQL(":memory:");
const sql2 = new SQL("sqlite://app.db");
const sql3 = new SQL("file://./database.db");

// Works with DATABASE_URL environment variable
DATABASE_URL=":memory:" bun run app.js
DATABASE_URL="sqlite://myapp.db" bun run app.js
DATABASE_URL="file://./data/app.db" bun run app.js

PostgreSQL Auto-Detection

PostgreSQL is the default for connection strings that don’t match MySQL or SQLite patterns:

# PostgreSQL is detected for these patterns
DATABASE_URL="postgres://user:pass@localhost:5432/mydb" bun run app.js
DATABASE_URL="postgresql://user:pass@localhost:5432/mydb" bun run app.js

# Or any URL that doesn't match MySQL or SQLite patterns
DATABASE_URL="localhost:5432/mydb" bun run app.js

MySQL Environment Variables

MySQL connections can be configured with environment variables:

# Primary connection URL (checked first)
MYSQL_URL="mysql://user:pass@localhost:3306/mydb"

# Alternative: DATABASE_URL with MySQL protocol
DATABASE_URL="mysql://user:pass@localhost:3306/mydb"
DATABASE_URL="mysql2://user:pass@localhost:3306/mydb"

If no connection URL is provided, Bun checks these individual parameters:

Environment Variable	Default Value	Description
`MYSQL_HOST`	`localhost`	Database host
`MYSQL_PORT`	`3306`	Database port
`MYSQL_USER`	`root`	Database user
`MYSQL_PASSWORD`	(empty)	Database password
`MYSQL_DATABASE`	`mysql`	Database name
`MYSQL_URL`	(empty)	Primary connection URL for MySQL
`TLS_MYSQL_DATABASE_URL`	(empty)	SSL/TLS-enabled connection URL

PostgreSQL Environment Variables

These environment variables define the PostgreSQL connection:

Environment Variable	Description
`POSTGRES_URL`	Primary connection URL for PostgreSQL
`DATABASE_URL`	Alternative connection URL (auto-detected)
`PGURL`	Alternative connection URL
`PG_URL`	Alternative connection URL
`TLS_POSTGRES_DATABASE_URL`	SSL/TLS-enabled connection URL
`TLS_DATABASE_URL`	Alternative SSL/TLS-enabled connection URL

If no connection URL is provided, Bun checks these individual parameters:

Environment Variable	Fallback Variables	Default Value	Description
`PGHOST`	-	`localhost`	Database host
`PGPORT`	-	`5432`	Database port
`PGUSERNAME`	`PGUSER`, `USER`, `USERNAME`	`postgres`	Database user
`PGPASSWORD`	-	(empty)	Database password
`PGDATABASE`	-	username	Database name

SQLite Environment Variables

SQLite connections can be configured with DATABASE_URL when it contains a SQLite-compatible URL:

# These are all recognized as SQLite
DATABASE_URL=":memory:"
DATABASE_URL="sqlite://./app.db"
DATABASE_URL="file:///absolute/path/to/db.sqlite"

Note: PostgreSQL-specific environment variables such as POSTGRES_URL and PGHOST are ignored when using SQLite.

Runtime Preconnection

Bun can preconnect to PostgreSQL at startup, before your application code runs, so the first query doesn’t pay the connection latency.

# Enable PostgreSQL preconnection
bun --sql-preconnect index.js

# Works with DATABASE_URL environment variable
DATABASE_URL=postgres://user:pass@localhost:5432/db bun --sql-preconnect index.js

# Can be combined with other runtime flags
bun --sql-preconnect --hot index.js

The --sql-preconnect flag establishes a PostgreSQL connection at startup using your configured environment variables. If the connection fails, the error is handled without crashing your application.

Connection Options

You can configure the connection manually by passing options to the SQL constructor. Options vary by adapter:

MySQL Options

import { SQL } from "bun";

const sql = new SQL({
  // Required for MySQL when using options object
  adapter: "mysql",

  // Connection details
  hostname: "localhost",
  port: 3306,
  database: "myapp",
  username: "dbuser",
  password: "secretpass",

  // Unix socket connection (alternative to hostname/port)
  // socket: "/var/run/mysqld/mysqld.sock",

  // Connection pool settings
  max: 20, // Maximum connections in pool (default: 10)
  idleTimeout: 30, // Close idle connections after 30s
  maxLifetime: 0, // Connection lifetime in seconds (0 = forever)
  connectionTimeout: 30, // Timeout when establishing new connections

  // SSL/TLS options
  ssl: "prefer", // or "disable", "require", "verify-ca", "verify-full"
  // tls: {
  //   rejectUnauthorized: true,
  //   ca: "path/to/ca.pem",
  //   key: "path/to/key.pem",
  //   cert: "path/to/cert.pem",
  // },

  // Callbacks
  onconnect: client => {
    console.log("Connected to MySQL");
  },
  onclose: (client, err) => {
    if (err) {
      console.error("MySQL connection error:", err);
    } else {
      console.log("MySQL connection closed");
    }
  },
});

PostgreSQL Options

import { SQL } from "bun";

const sql = new SQL({
  // Connection details (adapter is auto-detected as PostgreSQL)
  url: "postgres://user:pass@localhost:5432/dbname",

  // Alternative connection parameters
  hostname: "localhost",
  port: 5432,
  database: "myapp",
  username: "dbuser",
  password: "secretpass",

  // Connection pool settings
  max: 20, // Maximum connections in pool
  idleTimeout: 30, // Close idle connections after 30s
  maxLifetime: 0, // Connection lifetime in seconds (0 = forever)
  connectionTimeout: 30, // Timeout when establishing new connections

  // SSL/TLS options
  tls: true,
  // tls: {
  //   rejectUnauthorized: true,
  //   requestCert: true,
  //   ca: "path/to/ca.pem",
  //   key: "path/to/key.pem",
  //   cert: "path/to/cert.pem",
  //   checkServerIdentity(hostname, cert) {
  //     ...
  //   },
  // },

  // Callbacks
  onconnect: client => {
    console.log("Connected to PostgreSQL");
  },
  onclose: client => {
    console.log("PostgreSQL connection closed");
  },
});

SQLite Options

import { SQL } from "bun";

const sql = new SQL({
  // Required for SQLite
  adapter: "sqlite",
  filename: "./data/app.db", // or ":memory:" for in-memory database

  // SQLite-specific access modes
  readonly: false, // Open in read-only mode
  create: true, // Create database if it doesn't exist
  readwrite: true, // Allow read and write operations

  // SQLite data handling
  strict: true, // Enable strict mode for better type safety
  safeIntegers: false, // Use BigInt for integers exceeding JS number range

  // Callbacks
  onconnect: client => {
    console.log("SQLite database opened");
  },
  onclose: client => {
    console.log("SQLite database closed");
  },
});

SQLite Connection Notes

Connection Pooling: SQLite doesn’t use connection pooling as it’s a file-based database. Each SQL instance represents a single connection.
Transactions: SQLite supports nested transactions through savepoints, similar to PostgreSQL.
Concurrent Access: SQLite handles concurrent access through file locking. Use WAL mode for better concurrency.
Memory Databases: Using :memory: creates a temporary database that exists only for the connection lifetime.

Dynamic passwords

For alternative authentication schemes such as access tokens, or databases with rotating passwords, set password to a synchronous or asynchronous function. Bun calls it at connection time to resolve the password.

import { SQL } from "bun";

const sql = new SQL(url, {
  // Other connection config
  ...
  // Password function for the database user
  password: async () => await signer.getAuthToken(),
});

SQLite-Specific Features

Query Execution

SQLite executes queries synchronously, unlike PostgreSQL, which uses asynchronous I/O. The API still returns Promises:

const sqlite = new SQL("sqlite://app.db");

// Works the same as PostgreSQL, but executes synchronously under the hood
const users = await sqlite`SELECT * FROM users`;

// Parameters work identically
const user = await sqlite`SELECT * FROM users WHERE id = ${userId}`;

SQLite Pragmas

Use PRAGMA statements to configure SQLite behavior:

const sqlite = new SQL("sqlite://app.db");

// Enable foreign keys
await sqlite`PRAGMA foreign_keys = ON`;

// Set journal mode to WAL for better concurrency
await sqlite`PRAGMA journal_mode = WAL`;

// Check integrity
const integrity = await sqlite`PRAGMA integrity_check`;

Data Type Differences

SQLite has a more flexible type system than PostgreSQL:

// SQLite stores data in 5 storage classes: NULL, INTEGER, REAL, TEXT, BLOB
const sqlite = new SQL("sqlite://app.db");

// SQLite is more lenient with types
await sqlite`
  CREATE TABLE flexible (
    id INTEGER PRIMARY KEY,
    data TEXT,        -- Can store numbers as strings
    value NUMERIC,    -- Can store integers, reals, or text
    blob BLOB         -- Binary data
  )
`;

// JavaScript values are automatically converted
await sqlite`INSERT INTO flexible VALUES (${1}, ${"text"}, ${123.45}, ${Buffer.from("binary")})`;

Transactions

To start a new transaction, use sql.begin. This method works for both PostgreSQL and SQLite. For PostgreSQL, it reserves a dedicated connection from the pool. For SQLite, it begins a transaction on the single connection. The BEGIN command is sent automatically, including any optional configurations you specify. If an error occurs during the transaction, Bun issues a ROLLBACK.

Basic Transactions

await sql.begin(async tx => {
  // All queries in this function run in a transaction
  await tx`INSERT INTO users (name) VALUES (${"Alice"})`;
  await tx`UPDATE accounts SET balance = balance - 100 WHERE user_id = 1`;

  // Transaction automatically commits if no errors are thrown
  // Rolls back if any error occurs
});

To pipeline the queries in a transaction, return an array of queries from the callback:

await sql.begin(async tx => {
  return [
    tx`INSERT INTO users (name) VALUES (${"Alice"})`,
    tx`UPDATE accounts SET balance = balance - 100 WHERE user_id = 1`,
  ];
});

Savepoints

Savepoints create intermediate checkpoints within a transaction, so part of it can roll back without aborting the whole thing.

await sql.begin(async tx => {
  await tx`INSERT INTO users (name) VALUES (${"Alice"})`;

  await tx.savepoint(async sp => {
    // This part can be rolled back separately
    await sp`UPDATE users SET status = 'active'`;
    if (someCondition) {
      throw new Error("Rollback to savepoint");
    }
  });

  // Continue with transaction even if savepoint rolled back
  await tx`INSERT INTO audit_log (action) VALUES ('user_created')`;
});

Distributed Transactions

Two-Phase Commit (2PC) is a distributed transaction protocol: in phase 1 the coordinator prepares each node, making sure its data is written and ready to commit, and in phase 2 the nodes commit or roll back based on the coordinator’s decision. In PostgreSQL and MySQL, distributed transactions persist beyond their original session, so privileged users or coordinators can commit or roll them back later. PostgreSQL implements them as prepared transactions; MySQL uses XA Transactions. An uncaught exception during the distributed transaction rolls back all changes. Otherwise, you can commit or roll back the transaction later.

// Begin a distributed transaction
await sql.beginDistributed("tx1", async tx => {
  await tx`INSERT INTO users (name) VALUES (${"Alice"})`;
});

// Later, commit or rollback
await sql.commitDistributed("tx1");
// or
await sql.rollbackDistributed("tx1");

Authentication

Bun supports SCRAM-SHA-256 (SASL), MD5, and Clear Text authentication. SASL is recommended for better security. See Postgres SASL Authentication.

SSL Modes Overview

PostgreSQL’s SSL/TLS modes control whether a secure connection is required and how much certificate verification is performed.

const sql = new SQL({
  hostname: "localhost",
  username: "user",
  password: "password",
  ssl: "disable", // | "prefer" | "require" | "verify-ca" | "verify-full"
});

SSL Mode	Description
`disable`	No SSL/TLS used. Connections fail if server requires SSL.
`prefer`	Tries SSL first, falls back to non-SSL if SSL fails. Default mode if none specified.
`require`	Requires SSL without certificate verification. Fails if SSL cannot be established.
`verify-ca`	Verifies server certificate is signed by trusted CA. Fails if verification fails.
`verify-full`	Most secure mode. Verifies certificate and hostname match. Protects against untrusted certificates and MITM attacks.

Using With Connection Strings

You can also set the SSL mode in the connection string:

// Using prefer mode
const sql = new SQL("postgres://user:password@localhost/mydb?sslmode=prefer");

// Using verify-full mode
const sql = new SQL("postgres://user:password@localhost/mydb?sslmode=verify-full");

Connection Pooling

Bun’s SQL client manages a connection pool: database connections are reused across queries instead of being opened and closed for each one, and the pool caps the number of concurrent connections.

const sql = new SQL({
  // Pool configuration
  max: 20, // Maximum 20 concurrent connections
  idleTimeout: 30, // Close idle connections after 30s
  maxLifetime: 3600, // Max connection lifetime 1 hour
  connectionTimeout: 10, // Connection timeout 10s
});

No connection is made until you run a query.

const sql = Bun.SQL(); // no connection are created

await sql`...`; // pool is started until max is reached (if possible), first available connection is used
await sql`...`; // previous connection is reused

// two connections are used now at the same time
await Promise.all([
  sql`INSERT INTO users ${sql({ name: "Alice" })}`,
  sql`UPDATE users SET name = ${user.name} WHERE id = ${user.id}`,
]);

await sql.close(); // await all queries to finish and close all connections from the pool
await sql.close({ timeout: 5 }); // wait 5 seconds and close all connections from the pool
await sql.close({ timeout: 0 }); // close all connections from the pool immediately

Reserved Connections

sql.reserve() takes a connection from the pool and returns a client that wraps it, so you can run queries on an isolated connection.

// Get exclusive connection from pool
const reserved = await sql.reserve();

try {
  await reserved`INSERT INTO users (name) VALUES (${"Alice"})`;
} finally {
  // Important: Release connection back to pool
  reserved.release();
}

// Or using Symbol.dispose
{
  using reserved = await sql.reserve();
  await reserved`SELECT 1`;
} // Automatically released

Prepared Statements

By default, Bun’s SQL client creates named prepared statements for queries it can infer are static, which is faster. To disable this, set prepare: false in the connection options:

const sql = new SQL({
  // ... other options ...
  prepare: false, // Disable persisting named prepared statements on the server
});

When prepare: false is set: Queries still use the “extended” protocol, but run as unnamed prepared statements. An unnamed prepared statement lasts only until the next Parse statement specifying the unnamed statement as destination is issued.

Parameter binding is still safe against SQL injection
Each query is parsed and planned from scratch by the server
Queries are not pipelined

You might want to use prepare: false when:

Using PGBouncer in transaction mode (though since PGBouncer 1.21.0, protocol-level named prepared statements are supported when configured properly)
Debugging query execution plans
Working with dynamic SQL where query plans need to be regenerated frequently
Only one command per query is supported (unless you use sql``.simple())

Disabling prepared statements can slow down queries that run frequently with different parameters, since the server parses and plans each one from scratch.

Error Handling

The client provides typed errors for different failure scenarios. Errors are database-specific and extend a base error class:

Error Classes

import { SQL } from "bun";

try {
  await sql`SELECT * FROM users`;
} catch (error) {
  if (error instanceof SQL.PostgresError) {
    // PostgreSQL-specific error
    console.log(error.code); // PostgreSQL error code
    console.log(error.detail); // Detailed error message
    console.log(error.hint); // Helpful hint from PostgreSQL
  } else if (error instanceof SQL.SQLiteError) {
    // SQLite-specific error
    console.log(error.code); // SQLite error code (e.g., "SQLITE_CONSTRAINT")
    console.log(error.errno); // SQLite error number
    console.log(error.byteOffset); // Byte offset in SQL statement (if available)
  } else if (error instanceof SQL.SQLError) {
    // Generic SQL error (base class)
    console.log(error.message);
  }
}

PostgreSQL-Specific Error Codes

PostgreSQL Connection Errors

Connection Errors	Description
`ERR_POSTGRES_CONNECTION_CLOSED`	An established connection was terminated
`ERR_POSTGRES_CONNECTION_FAILED`	Connection was accepted but closed before the handshake completed (e.g. the server is still starting up). Retried with backoff until `connectionTimeout` while queries are waiting. Note: errors the server sends during startup, like `57P03`, surface as `ERR_POSTGRES_SERVER_ERROR`
`ERR_POSTGRES_CONNECTION_REFUSED`	Connection was refused because nothing is listening at the address. Fails immediately and is not retried
`ERR_POSTGRES_CONNECTION_TIMEOUT`	Failed to establish connection within timeout period
`ERR_POSTGRES_IDLE_TIMEOUT`	Connection closed due to inactivity
`ERR_POSTGRES_LIFETIME_TIMEOUT`	Connection exceeded maximum lifetime
`ERR_POSTGRES_TLS_NOT_AVAILABLE`	SSL/TLS connection not available
`ERR_POSTGRES_TLS_UPGRADE_FAILED`	Failed to upgrade connection to SSL/TLS

Authentication Errors

Authentication Errors	Description
`ERR_POSTGRES_AUTHENTICATION_FAILED_PBKDF2`	Password authentication failed
`ERR_POSTGRES_UNKNOWN_AUTHENTICATION_METHOD`	Server requested unknown auth method
`ERR_POSTGRES_UNSUPPORTED_AUTHENTICATION_METHOD`	Server requested unsupported auth method
`ERR_POSTGRES_INVALID_SERVER_KEY`	Invalid server key during authentication
`ERR_POSTGRES_INVALID_SERVER_SIGNATURE`	Invalid server signature
`ERR_POSTGRES_SASL_SIGNATURE_INVALID_BASE64`	Invalid SASL signature encoding
`ERR_POSTGRES_SASL_SIGNATURE_MISMATCH`	SASL signature verification failed

Query Errors

Query Errors	Description
`ERR_POSTGRES_SYNTAX_ERROR`	Invalid SQL syntax (extends `SyntaxError`)
`ERR_POSTGRES_SERVER_ERROR`	General error from PostgreSQL server
`ERR_POSTGRES_INVALID_QUERY_BINDING`	Invalid parameter binding
`ERR_POSTGRES_QUERY_CANCELLED`	Query was cancelled
`ERR_POSTGRES_NOT_TAGGED_CALL`	Query was called without a tagged call

Data Type Errors

Data Type Errors	Description
`ERR_POSTGRES_INVALID_BINARY_DATA`	Invalid binary data format
`ERR_POSTGRES_INVALID_BYTE_SEQUENCE`	Invalid byte sequence
`ERR_POSTGRES_INVALID_BYTE_SEQUENCE_FOR_ENCODING`	Encoding error
`ERR_POSTGRES_INVALID_CHARACTER`	Invalid character in data
`ERR_POSTGRES_OVERFLOW`	Numeric overflow
`ERR_POSTGRES_UNSUPPORTED_BYTEA_FORMAT`	Unsupported binary format
`ERR_POSTGRES_UNSUPPORTED_INTEGER_SIZE`	Integer size not supported
`ERR_POSTGRES_MULTIDIMENSIONAL_ARRAY_NOT_SUPPORTED_YET`	Multidimensional arrays not supported
`ERR_POSTGRES_NULLS_IN_ARRAY_NOT_SUPPORTED_YET`	NULL values in arrays not supported

Protocol Errors

Protocol Errors	Description
`ERR_POSTGRES_EXPECTED_REQUEST`	Expected client request
`ERR_POSTGRES_EXPECTED_STATEMENT`	Expected prepared statement
`ERR_POSTGRES_INVALID_BACKEND_KEY_DATA`	Invalid backend key data
`ERR_POSTGRES_INVALID_MESSAGE`	Invalid protocol message
`ERR_POSTGRES_INVALID_MESSAGE_LENGTH`	Invalid message length
`ERR_POSTGRES_UNEXPECTED_MESSAGE`	Unexpected message type

Transaction Errors

Transaction Errors	Description
`ERR_POSTGRES_UNSAFE_TRANSACTION`	Unsafe transaction operation detected
`ERR_POSTGRES_INVALID_TRANSACTION_STATE`	Invalid transaction state

SQLite-Specific Errors

SQLite errors carry SQLite’s standard error codes and numbers:

Common SQLite Error Codes

Error Code	errno	Description
`SQLITE_CONSTRAINT`	19	Constraint violation (UNIQUE, CHECK, NOT NULL, etc.)
`SQLITE_BUSY`	5	Database is locked
`SQLITE_LOCKED`	6	Table in the database is locked
`SQLITE_READONLY`	8	Attempt to write to a readonly database
`SQLITE_IOERR`	10	Disk I/O error
`SQLITE_CORRUPT`	11	Database disk image is malformed
`SQLITE_FULL`	13	Database or disk is full
`SQLITE_CANTOPEN`	14	Unable to open database file
`SQLITE_PROTOCOL`	15	Database lock protocol error
`SQLITE_SCHEMA`	17	Database schema has changed
`SQLITE_TOOBIG`	18	String or BLOB exceeds size limit
`SQLITE_MISMATCH`	20	Data type mismatch
`SQLITE_MISUSE`	21	Library used incorrectly
`SQLITE_AUTH`	23	Authorization denied

Example error handling:

const sqlite = new SQL("sqlite://app.db");

try {
  await sqlite`INSERT INTO users (id, name) VALUES (1, 'Alice')`;
  await sqlite`INSERT INTO users (id, name) VALUES (1, 'Bob')`; // Duplicate ID
} catch (error) {
  if (error instanceof SQL.SQLiteError) {
    if (error.code === "SQLITE_CONSTRAINT") {
      console.log("Constraint violation:", error.message);
      // Handle unique constraint violation
    }
  }
}

Numbers and BigInt

Numbers that exceed the range of a 53-bit integer are returned as strings:

import { sql } from "bun";

const [{ x, y }] = await sql`SELECT 9223372036854777 as x, 12345 as y`;

console.log(typeof x, x); // "string" "9223372036854777"
console.log(typeof y, y); // "number" 12345

BigInt Instead of Strings

To get large numbers as BigInt instead of strings, set the bigint option to true when creating the SQL client:

const sql = new SQL({
  bigint: true,
});

const [{ x }] = await sql`SELECT 9223372036854777 as x`;

console.log(typeof x, x); // "bigint" 9223372036854777n

Roadmap

Things we haven’t finished yet:

Connection preloading with the --db-preconnect Bun CLI flag
Column name transforms (for example, snake_case to camelCase). This is mostly blocked on a unicode-aware implementation of changing the case in C++ using WebKit’s WTF::String.
Column type transforms

Database-Specific Features

Authentication Methods

MySQL supports multiple authentication plugins that are automatically negotiated:

mysql_native_password - Traditional MySQL authentication, widely compatible
caching_sha2_password - Default in MySQL 8.0+, more secure with RSA key exchange
sha256_password - SHA-256 based authentication

The client automatically handles authentication plugin switching when requested by the server, including secure password exchange over non-SSL connections.

Prepared Statements & Performance

MySQL uses server-side prepared statements for all parameterized queries:

// This automatically creates a prepared statement on the server
const user = await mysql`SELECT * FROM users WHERE id = ${userId}`;

// Prepared statements are cached and reused for identical queries
for (const id of userIds) {
  // Same prepared statement is reused
  await mysql`SELECT * FROM users WHERE id = ${id}`;
}

// Query pipelining - multiple statements sent without waiting
const [users, orders, products] = await Promise.all([
  mysql`SELECT * FROM users WHERE active = ${true}`,
  mysql`SELECT * FROM orders WHERE status = ${"pending"}`,
  mysql`SELECT * FROM products WHERE in_stock = ${true}`,
]);

Multiple Result Sets

MySQL can return multiple result sets from multi-statement queries:

const mysql = new SQL("mysql://user:pass@localhost/mydb");

// Multi-statement queries with simple() method
const multiResults = await mysql`
  SELECT * FROM users WHERE id = 1;
  SELECT * FROM orders WHERE user_id = 1;
`.simple();

Character Sets & Collations

Bun.SQL uses the utf8mb4 character set for MySQL connections, which covers all of Unicode, including emoji.

Connection Attributes

Bun sends client information to MySQL for monitoring:

// These attributes are sent automatically:
// _client_name: "Bun"
// _client_version: <bun version>
// You can see these in MySQL's performance_schema.session_connect_attrs

Type Handling

MySQL types are converted to JavaScript types:

MySQL Type	JavaScript Type	Notes
INT, TINYINT, MEDIUMINT	number	Within safe integer range
BIGINT	string, number or BigInt	number if the value fits in i32/u32, otherwise string or BigInt depending on the `bigint` option
DECIMAL, NUMERIC	string	To preserve precision
FLOAT, DOUBLE	number
DATE	Date	JavaScript Date object
DATETIME, TIMESTAMP	Date	Decoded as UTC (see note below); `0000-00-00` becomes an Invalid Date
TIME	number	Total of microseconds
YEAR	number
CHAR, VARCHAR, VARSTRING, STRING	string
TINY TEXT, MEDIUM TEXT, TEXT, LONG TEXT	string
TINY BLOB, MEDIUM BLOB, BLOB, LONG BLOB	string	BLOB types are aliases for the TEXT types
JSON	object/array	Automatically parsed
BIT(1)	boolean	BIT(1) in MySQL
GEOMETRY	string	Geometry data

DATETIME and TIMESTAMP values have no timezone on the wire, so Bun reads them back as UTC — the Date you get has the same UTC wall-clock that was stored, regardless of the machine’s timezone. This matches how values are written (a bound Date stores its UTC components). The same applies to PostgreSQL’s timestamp (without time zone); timestamptz carries an explicit offset and is unaffected.

Differences from PostgreSQL

The API is unified, but behavior differs:

Parameter placeholders: MySQL uses ? internally but Bun converts $1, $2 style automatically
RETURNING clause: MySQL doesn’t support RETURNING; use result.lastInsertRowid or a separate SELECT
Array types: MySQL doesn’t have native array types like PostgreSQL

MySQL-Specific Features

We haven’t implemented LOAD DATA INFILE support yet.

PostgreSQL-Specific Features

We haven’t implemented these yet:

COPY support
LISTEN support
NOTIFY support

We also haven’t implemented some of the more uncommon features like:

GSSAPI authentication
SCRAM-SHA-256-PLUS support
Point & PostGIS types
All the multi-dimensional integer array types (only a couple of the types are supported)

Common Patterns & Best Practices

Working with MySQL Result Sets

// Getting insert ID after INSERT
const result = await mysql`INSERT INTO users (name) VALUES (${"Alice"})`;
console.log(result.lastInsertRowid); // MySQL's LAST_INSERT_ID()

// Handling affected rows
const updated = await mysql`UPDATE users SET active = ${false} WHERE age < ${18}`;
console.log(updated.affectedRows); // Number of rows updated

// Using MySQL-specific functions
const now = await mysql`SELECT NOW() as current_time`;
const uuid = await mysql`SELECT UUID() as id`;

MySQL Error Handling

try {
  await mysql`INSERT INTO users (email) VALUES (${"duplicate@email.com"})`;
} catch (error) {
  if (error.code === "ER_DUP_ENTRY") {
    console.log("Duplicate entry detected");
  } else if (error.code === "ER_ACCESS_DENIED_ERROR") {
    console.log("Access denied");
  } else if (error.code === "ER_BAD_DB_ERROR") {
    console.log("Database does not exist");
  }
  // MySQL error codes are compatible with mysql/mysql2 packages
}

Performance Tips for MySQL

Use connection pooling: Set appropriate max pool size based on your workload
Enable prepared statements: They’re enabled by default and improve performance
Use transactions for bulk operations: Group related queries in transactions
Index properly: MySQL relies heavily on indexes for query performance
Use utf8mb4 charset: It’s set by default and handles all Unicode characters

Frequently Asked Questions

Why is this `Bun.sql` and not `Bun.postgres`?

The plan was to add more database drivers. The unified API now supports PostgreSQL, MySQL, and SQLite.

How do I know which database adapter is being used?

The adapter is automatically detected from the connection string:

URLs starting with mysql:// or mysql2:// use MySQL
URLs matching SQLite patterns (:memory:, sqlite://, file://) use SQLite
Everything else defaults to PostgreSQL

Are MySQL stored procedures supported?

Yes, stored procedures are supported, including OUT parameters and multiple result sets:

// Call stored procedure
const results = await mysql`CALL GetUserStats(${userId}, @total_orders)`;

// Get OUT parameter
const outParam = await mysql`SELECT @total_orders as total`;

Can I use MySQL-specific SQL syntax?

Yes, you can use any MySQL-specific syntax:

// MySQL-specific syntax works fine
await mysql`SET @user_id = ${userId}`;
await mysql`SHOW TABLES`;
await mysql`DESCRIBE users`;
await mysql`EXPLAIN SELECT * FROM users WHERE id = ${id}`;

Why not just use an existing library?

You can use npm packages like postgres.js, pg, and node-postgres in Bun too. They’re great options. Two reasons why:

We think it’s simpler for developers to have a database driver built into Bun. The time you spend library shopping is time you could be building your app.
We use some JavaScriptCore engine internals to create objects faster, in ways that would be difficult to implement in a library.

Credits

Huge thanks to @porsager’s postgres.js for the inspiration for the API interface.

​Features

​Database Support

​PostgreSQL

​MySQL

​SQLite

​Inserting data

​Bulk Insert

​Picking columns to insert

​Query Results

​sql``.values() format

​sql``.raw() format

​SQL Fragments

​Dynamic Table Names

​Conditional Queries

​Dynamic columns in updates

​Dynamic values and where in

​sql.array helper

​sql``.simple()

​Queries in files

​Unsafe Queries

​Execute and Cancelling Queries

​Database Environment Variables

​Automatic Database Detection

​MySQL Auto-Detection

​SQLite Auto-Detection

​PostgreSQL Auto-Detection

​MySQL Environment Variables

​PostgreSQL Environment Variables

​SQLite Environment Variables

​Runtime Preconnection

​Connection Options

​MySQL Options

​PostgreSQL Options

​SQLite Options

​Dynamic passwords

​SQLite-Specific Features

​Query Execution

​SQLite Pragmas

​Data Type Differences

​Transactions

​Basic Transactions

​Savepoints

​Distributed Transactions

​Authentication

​SSL Modes Overview

​Using With Connection Strings

​Connection Pooling

​Reserved Connections

​Prepared Statements

​Error Handling

​Error Classes

​PostgreSQL Connection Errors

​Authentication Errors

​Query Errors

​Data Type Errors

​Protocol Errors

​Transaction Errors

​SQLite-Specific Errors

​Numbers and BigInt

​BigInt Instead of Strings

​Roadmap

​Database-Specific Features

​Authentication Methods

​Prepared Statements & Performance

​Multiple Result Sets

​Character Sets & Collations

​Connection Attributes

​Type Handling

​Differences from PostgreSQL

​MySQL-Specific Features

​PostgreSQL-Specific Features

​Common Patterns & Best Practices

​Working with MySQL Result Sets

​MySQL Error Handling

​Performance Tips for MySQL

​Frequently Asked Questions

​Why not just use an existing library?

​Credits

Features

Database Support

PostgreSQL

MySQL

SQLite

Inserting data

Bulk Insert

Picking columns to insert

Query Results

sql``.values() format

sql``.raw() format

SQL Fragments

Dynamic Table Names

Conditional Queries

Dynamic columns in updates

Dynamic values and `where in`

`sql.array` helper

sql``.simple()

Queries in files

Unsafe Queries

Execute and Cancelling Queries

Database Environment Variables

Automatic Database Detection

MySQL Auto-Detection

SQLite Auto-Detection

PostgreSQL Auto-Detection

MySQL Environment Variables

PostgreSQL Environment Variables

SQLite Environment Variables

Runtime Preconnection

Connection Options

MySQL Options

PostgreSQL Options

SQLite Options

Dynamic passwords

SQLite-Specific Features

Query Execution

SQLite Pragmas

Data Type Differences

Transactions

Basic Transactions

Savepoints

Distributed Transactions

Authentication

SSL Modes Overview

Using With Connection Strings

Connection Pooling

Reserved Connections

Prepared Statements

Error Handling

Error Classes

PostgreSQL Connection Errors

Authentication Errors

Query Errors

Data Type Errors

Protocol Errors

Transaction Errors

SQLite-Specific Errors

Numbers and BigInt

BigInt Instead of Strings

Roadmap

Database-Specific Features

Authentication Methods

Prepared Statements & Performance

Multiple Result Sets

Character Sets & Collations

Connection Attributes

Type Handling

Differences from PostgreSQL

MySQL-Specific Features

PostgreSQL-Specific Features

Common Patterns & Best Practices

Working with MySQL Result Sets

MySQL Error Handling

Performance Tips for MySQL

Frequently Asked Questions

Why not just use an existing library?

Credits