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Query databases

This guide documents D1’s client API and how to query D1 from Cloudflare Workers, how D1 maps types from JavaScript/TypeScript and SQL, and common errors returned by D1.

​​ Prepared and static statements

As part of our Client API, both static and prepared statements are supported. Best practice is to use prepared statements which are precompiled objects used by the database to run the SQL. This is because prepared statements lead to overall faster execution and prevent SQL injection attacks.

Below is an example of a prepared statement:

const stmt = db.prepare('SELECT * FROM users WHERE name = ?1').bind('Joe');

However, if you still choose to use a static statement you can use the following as an example:

const stmt = db.prepare('SELECT * FROM users WHERE name = "John Doe"');

​​ Parameter binding

D1 follows the SQLite convention for prepared statements parameter binding. Currently, D1 only supports Ordered (?NNNN) and Anonymous (?) parameters. In the future, D1 will support named parameters as well.

SyntaxTypeDescription
?NNNOrderedA question mark followed by a number NNN holds a spot for the NNN-th parameter. NNN must be between 1 and SQLITE_MAX_VARIABLE_NUMBER
?AnonymousA question mark that is not followed by a number creates a parameter with a number one greater than the largest parameter number already assigned. If this means the parameter number is greater than SQLITE_MAX_VARIABLE_NUMBER, it is an error. This parameter format is provided for compatibility with other database engines. But because it is easy to miscount the question marks, the use of this parameter format is discouraged. Programmers are encouraged to use one of the symbolic formats below or the ?NNN format above instead

To bind a parameter, use the stmt.bind() method.

​​ Order and anonymous examples:

const stmt = db.prepare('SELECT * FROM users WHERE name = ?').bind( 'John Doe' );
const stmt = db.prepare('SELECT * FROM users WHERE name = ? AND age = ?').bind( 'John Doe', 41 );
const stmt = db.prepare('SELECT * FROM users WHERE name = ?2 AND age = ?1').bind( 41, 'John Doe' );

​​ Type conversion

D1 automatically converts supported JavaScript (including TypeScript) types passed as parameters via the client API to their associated D1 types. The type conversion is as follows:

JavaScriptD1
nullNULL
NumberREAL
Number 1INTEGER
StringTEXT
Boolean 2INTEGER
ArrayBufferBLOB
undefinedNot supported. Queries with undefined values will return a D1_TYPE_ERROR

1 D1 supports 64-bit signed INTEGER values internally, however BigInts are not currently supported in the API yet. JavaScript integers are safe up to Number.MAX_SAFE_INTEGER.

2 Booleans will be cast to an INTEGER type where 1 is TRUE and 0 is FALSE.

​​ Return object

The methods stmt.all() and db.batch() return a typed D1Result object that contains the results (if applicable), the success status, and a meta object with the internal duration of the operation in milliseconds.

{
results: array | null, // [] if empty, or null if it does not apply
success: boolean, // true if the operation was successful, false otherwise
meta: {
duration: number, // duration of the operation in milliseconds
rows_read: number, // the number of rows read (scanned) by this query
rows_written: number // the number of rows written by this query
}
}

Example:

const { duration } = (await db.prepare('INSERT INTO users (name, age) VALUES (?1, ?2)').bind( "John", 42 ).run()).meta;
console.log(duration); // 0.172

The db.exec() method returns a D1ExecResult object:

{
count: number, // the number of queries executed
duration: number // duration of the operation in milliseconds
}

​​ Query statement methods

The D1 API supports the following query statement methods for querying against a D1 database.

​​ await stmt.all()

Returns all rows as an array of objects, with each result row represented as an object on the results property of the D1Result type.

When joining tables with identical column names, only the leftmost column will be included in the row object. Use stmt.raw() to return all rows as an array of arrays.

const stmt = db.prepare('SELECT name, age FROM users LIMIT 3');
const { results } = await stmt.all();
console.log(results);
/*
[
{
name: "John",
age: 42,
},
{
name: "Anthony",
age: 37,
},
{
name: "Dave",
age: 29,
},
]
*/

​​ await stmt.raw()

Returns results as an array of arrays, with each row represented by an array. The return type is an array of arrays, and does not include query metadata.

Column names are not included in the result set by default. To include column names as the first row of the result array, set .raw({columnNames: true}).

const stmt = db.prepare('SELECT name, age FROM users LIMIT 3');
const rows = await stmt.raw();
console.log(rows);
/*
[
[ "John", 42 ],
[ "Anthony", 37 ],
[ "Dave", 29 ],
]
*/
// With columnNames: true
const stmt = db.prepare('SELECT name, age FROM users LIMIT 3');
const [columns, ...rows] = await stmt.raw({columnNames: true});
console.log(columns);
/*
[ "name", age ], // The first result array includes the column names
*/

​​ await stmt.first([column])

Returns the first row of the results. This does not return metadata like the other methods. Instead, it returns the object directly.

Get a specific column from the first row:

const stmt = db.prepare('SELECT COUNT(*) AS total FROM users');
const total = await stmt.first('total');
console.log(total); // 50

Get all the the columns from the first row:

const stmt = db.prepare('SELECT COUNT(*) AS total FROM users');
const values = await stmt.first();
console.log(values); // { total: 50 }

If the query returns no rows, then first() will return null.

If the query returns rows, but column does not exist, then first() will throw the D1_ERROR exception.

stmt.first() does not alter the SQL query. To improve performance, consider appending LIMIT 1 to your statement.

​​ await stmt.run()

Runs the query (or queries), but returns no results. Instead, run() returns the metrics only. Useful for write operations like UPDATE, DELETE or INSERT.

const info = await db.prepare('INSERT INTO users (name, age) VALUES (?1, ?2)')
.bind( "John", 42 )
.run()
console.log(info);
/*
{
success: true
meta: {
duration: 62,
}
}
*/

​​ await db.dump()

Dumps the entire D1 database to an SQLite compatible file inside an ArrayBuffer.

const dump = await db.dump()
return new Response(dump, {
status: 200,
headers: {
'Content-Type': 'application/octet-stream'
}
});

​​ await db.exec()

Executes one or more queries directly without prepared statements or parameters binding. This method can have poorer performance (prepared statements can be reused in some cases) and, more importantly, is less safe. Only use this method for maintenance and one-shot tasks (for example, migration jobs). The input can be one or multiple queries separated by \n.

If an error occurs, an exception is thrown with the query and error messages, execution stops and further statements are not executed. Refer to Errors to learn more.

const migration = await fetch('/migration.sql');
const out = await db.exec(migration.text());
console.log(out);
/*
{
count: 80,
duration: 76
}
*/

​​ TypeScript support

D1’s query API is fully-typed via the @cloudflare/workers-types package, and also supports generic types as part of its TypeScript API. A generic type allows you to provide an optional type parameter so that a function understands the type of the data it is handling.

When using the query statement methods stmt.all(), stmt.raw() and stmt.first(), you can provide a type representing each database row. D1’s API will return the result object with the correct type.

For example, providing an OrderRow type as a type parameter to stmt.all() will return a typed Array<OrderRow> object instead of the default Record<string, unknown> type:

// Row definition
type OrderRow = {
Id: string;
CustomerName: string;
OrderDate: number;
}
// Elsewhere in your application
const result = await env.MY_DB.prepare("SELECT Id, CustomerName, OrderDate FROM [Order] ORDER BY ShippedDate DESC LIMIT 100").all<OrderRow>();

​​ Reuse prepared statements

Prepared statements can be reused with new bindings:

const stmt = db.prepare('SELECT name, age FROM users WHERE age < ?1');
const young = await stmt.bind(20).all();
console.log(young);
/*
{
results: [...],
success: true
meta: {
duration: 31,
}
}
*/
const old = await stmt.bind(80).all();
console.log(old);
/*
{
results: [...],
success: true
meta: {
duration: 29,
}
}
*/

​​ Search with LIKE

Perform a search using SQL’s LIKE operator:

const { results } = await env.DB.prepare(
"SELECT * FROM Customers WHERE CompanyName LIKE ?"
)
.bind("%eve%")
.all();
console.log("results: ", results);
/*
results: [...]
*/

​​ Batch statements

Batching sends multiple SQL statements inside a single call to the database. This can have a huge performance impact as it reduces latency from network round trips to D1. D1 operates in auto-commit. Our implementation guarantees that each statement in the list will execute and commit, sequentially, non-concurrently.

Batched statements are SQL transactions. If a statement in the sequence fails, then an error is returned for that specific statement, and it aborts or rolls back the entire sequence.

​​ db.batch()

To send batch statements, provide batch() a list of prepared statements and get the results in the same order.

await db.batch([
db.prepare("UPDATE users SET name = ?1 WHERE id = ?2").bind( "John", 17 ),
db.prepare("UPDATE users SET age = ?1 WHERE id = ?2").bind( 35, 19 ),
]);

You can construct batches reusing the same prepared statement:

const stmt = db.prepare("SELECT * FROM users WHERE name = ?1");
const rows = await db.batch([
stmt.bind("John"),
stmt.bind("Anthony"),
]);
console.log(rows[0].results);
/*
[
{
name: "John Clemente",
age: 42,
},
{
name: "John Davis",
age: 37,
},
]
*/
console.log(rows[1].results);
/*
[
{
name: "Anthony Hopkins",
age: 66,
},
]
*/

​​ PRAGMA statements

D1 supports the following SQLite PRAGMA statements:

PRAGMADescription
table_listReturns information about the tables and views in the schema, one table per row of output.
table_infoThis pragma returns one row for each column in the named table. Columns in the result set include the column name, data type, whether or not the column can be NULL, and the default value for the column.
foreign_keysQuery, set, or clear the enforcement of foreign key constraints.

Other PRAGMAs are disabled because of D1 implementation specifics.

const r = await db.batch([
db.prepare("PRAGMA table_list"),
db.prepare("PRAGMA table_info(my_table)"),
]);
console.log(r);
/*
[
{
"results": [
{
"schema": "main",
"name": "my_table",
"type": "table",
"ncol": 3,
"wr": 0,
"strict": 0
},
...
]
},
{
"results": [
{
"cid": 0,
"name": "cid",
"type": "INTEGER",
"notnull": 0,
"dflt_value": null,
"pk": 1
},
...
]
}
]
*/

​​ Errors

The stmt. and db. methods will throw an Error object whenever an error occurs.

To capture exceptions, log the Error.message value. For example, the code below has a query with an invalid keyword - INSERTZ instead of INSERT:

try {
// This is an intentional mispelling
await db.exec("INSERTZ INTO my_table (name, employees) VALUES ()");
} catch (e: any) {
console.error({
message: e.message
});
}

The code above would throw the following error message:

{
"message": "D1_EXEC_ERROR: Error in line 1: INSERTZ INTO my_table (name, employees) VALUES (): sql error: near \"INSERTZ\": syntax error in INSERTZ INTO my_table (name, employees) VALUES () at offset 0"
}

​​ Error list

D1 will return the following error constants, in addition to the extended (detailed) error message:

MessageCause
D1_ERRORGeneric error.
D1_TYPE_ERRORReturned when there is a mismatch in the type between a column and a value. A common cause is supplying an undefined variable (unsupported) instead of null.
D1_COLUMN_NOTFOUNDColumn not found.
D1_DUMP_ERRORDatabase dump error.
D1_EXEC_ERRORExec error in line x: y error.