SQL
Bun provides native bindings for working with SQL databases through a unified Promise-based API that supports PostgreSQL, MySQL, and SQLite.
Queries are written as tagged template literals, and the client supports connection pooling, transactions, and prepared statements.
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
BigIntsupport- 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://orpostgresql://protocols - No connection string is provided and environment variables point to PostgreSQL
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+:
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 ${mysql(newUsers)}`;SQLite
SQLite support is built into Bun.SQL, with the same tagged template literal interface:
import { SQL } from "bun";
// In-memory database
const memory = new SQL(":memory:");
const memory2 = new SQL("sqlite://:memory:");
// File-based database
const sql1 = new SQL("sqlite://myapp.db");
// Using options object
const sql2 = new SQL({
adapter: "sqlite",
filename: "./data/app.db",
});
// For simple filenames, specify adapter explicitly
const sql3 = new SQL("myapp.db", { adapter: "sqlite" });Inserting data
Pass JavaScript values directly to the SQL template literal; Bun handles the escaping.
import { sql } from "bun";
// Basic insert with direct values
const [user] = await sql`
INSERT INTO users (name, email)
VALUES (${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 fieldsQuery 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 URLsmysql2://...- 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.jsSQLite Auto-Detection
SQLite is selected when the connection string matches these patterns:
:memory:- In-memory databasesqlite://...- SQLite protocol URLssqlite:...- SQLite protocol without slashesfile://...- File protocol URLsfile:...- 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.jsPostgreSQL 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.jsMySQL 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 |
PGSSLMODE | - | disable | SSL mode (disable, allow, prefer, require, verify-ca, verify-full) |
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.jsThe --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");
},
});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. Default mode if none specified. |
prefer | Tries SSL first, falls back to non-SSL if SSL fails. |
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 = ${user.id}`,
]);
await sql.close(); // await all queries to finish and close all connections from the pool
await sql.close({ timeout: 5 }); // wait 5 seconds and close all connections from the pool
await sql.close({ timeout: 0 }); // close all connections from the pool immediatelyReserved Connections
sql.reserve() takes a connection from the pool and returns a client that wraps it, so you can run queries on an isolated connection.
// Get exclusive connection from pool
const reserved = await sql.reserve();
try {
await reserved`INSERT INTO users (name) VALUES (${"Alice"})`;
} finally {
// Important: Release connection back to pool
reserved.release();
}
// Or using Symbol.dispose
{
using reserved = await sql.reserve();
await reserved`SELECT 1`;
} // Automatically releasedPrepared 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);
}
}SQLite-Specific Errors
SQLite errors carry SQLite's standard error codes and numbers:
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" 12345BigInt 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" 9223372036854777nRoadmap
Things we haven't finished yet:
- Connection preloading with the
--db-preconnectBun CLI flag - Column name transforms (for example,
snake_casetocamelCase). This is mostly blocked on a unicode-aware implementation of changing the case in C++ using WebKit'sWTF::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 compatiblecaching_sha2_password- Default in MySQL 8.0+, more secure with RSA key exchangesha256_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_attrsType 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, $2style automatically - RETURNING clause: MySQL doesn't support RETURNING; use
result.lastInsertRowidor a separate SELECT - Array types: MySQL doesn't have native array types like PostgreSQL
MySQL-Specific Features
We haven't implemented LOAD DATA INFILE support yet.
PostgreSQL-Specific Features
We haven't implemented these yet:
COPYsupportLISTENsupportNOTIFYsupport
We also haven't implemented some of the more uncommon features like:
- GSSAPI authentication
SCRAM-SHA-256-PLUSsupport- Point & PostGIS types
- All the multi-dimensional integer array types (only a couple of the types are supported)
Common Patterns & Best Practices
Working with MySQL Result Sets
// Getting insert ID after INSERT
const result = await mysql`INSERT INTO users (name) VALUES (${"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
maxpool 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
utf8mb4charset: It's set by default and handles all Unicode characters
Frequently Asked Questions
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.