Class: Database

Constructor

new Database(data)

Parameters:

Name	Type	Description
`data`	Array.<number>	An array of bytes representing an SQLite database file

Source: api.js, line 829

Methods

["close"]()

Close the database, and all associated prepared statements. The memory associated to the database and all associated statements will be freed.

Warning: A statement belonging to a database that has been closed cannot be used anymore.

Databases must be closed when you're finished with them, or the memory consumption will grow forever

Source: api.js, line 1113

["create_aggregate"](name, aggregateFunctions) → {Database}

Parameters:

Name Type Description

name

string

the name of the aggregate as referenced in SQL statements.

aggregateFunctions

object

object containing at least a step function.

Properties

Name	Type	Attributes	Description
`init=`	function	<optional>	a function receiving no arguments and returning an initial value for the aggregate function. The initial value will be null if this key is omitted.
`step`	function		a function receiving the current state and a value to aggregate and returning a new state. Will receive the value from init for the first step.
`finalize=`	function	<optional>	a function returning the result of the aggregate function given its final state. If omitted, the value returned by the last step will be used as the final value.

Source: api.js, line 1297

Returns:

The database object. Useful for method chaining

Type:: Database

Example

        db.create_aggregate("js_sum", {
            init: () => 0,
            step: (state, value) => state + value,
            finalize: state => state
        });
        db.exec("SELECT js_sum(column1) FROM (VALUES (1), (2))"); // = 3

["create_function"](name, func) → {Database}

Parameters:

Name	Type	Description
`name`	string	the name of the function as referenced in SQL statements.
`func`	function	the actual function to be executed.

Source: api.js, line 1231

Returns:

The database object. Useful for method chaining

Type:: Database

Example

          db.create_function("addOne", function (x) {return x+1;})
          db.exec("SELECT addOne(1)") // = 2

["each"](sql, params=opt, callback, done) → {Database}

Execute an sql statement, and call a callback for each row of result.

Currently this method is synchronous, it will not return until the callback
has been called on every row of the result. But this might change.

Parameters:

Name	Type	Attributes	Description
`sql`	string		A string of SQL text. Can contain placeholders that will be bound to the parameters given as the second argument
`params=`	Statement.BindParams	<optional>	Parameters to bind to the query
`callback`	function		Function to call on each row of result
`done`	function		A function that will be called when all rows have been retrieved

Source: api.js, line 1020

Returns:

The database object. Useful for method chaining

Type:: Database

Example

Read values from a table

    db.each("SELECT name,age FROM users WHERE age >= $majority", {$majority:18},
            function (row){console.log(row.name + " is a grown-up.")}
    );

["exec"](sql, paramsopt) → {Array.<Database.QueryExecResult>}

Execute an SQL query, and returns the result.

This is a wrapper against Database.prepare, Statement.bind, Statement.step, Statement.get, and Statement.free.

The result is an array of result elements. There are as many result elements as the number of statements in your sql string (statements are separated by a semicolon)

Example use

We will create the following table, named test and query it with a multi-line statement using params:

id	age	name
1	1	Ling
2	18	Paul

We query it like that:

var db = new SQL.Database();
var res = db.exec(
    "DROP TABLE IF EXISTS test;\n"
    + "CREATE TABLE test (id INTEGER, age INTEGER, name TEXT);"
    + "INSERT INTO test VALUES ($id1, :age1, @name1);"
    + "INSERT INTO test VALUES ($id2, :age2, @name2);"
    + "SELECT id FROM test;"
    + "SELECT age,name FROM test WHERE id=$id1",
    {
        "$id1": 1, ":age1": 1, "@name1": "Ling",
        "$id2": 2, ":age2": 18, "@name2": "Paul"
    }
);

res is now :

    [
        {"columns":["id"],"values":[[1],[2]]},
        {"columns":["age","name"],"values":[[1,"Ling"]]}
    ]

Parameters:

Name	Type	Attributes	Description
`sql`	string		a string containing some SQL text to execute
`params`	Statement.BindParams	<optional>	When the SQL statement contains placeholders, you can pass them in here. They will be bound to the statement before it is executed. If you use the params argument as an array, you cannot provide an sql string that contains several statements (separated by `;`). This limitation does not apply to params as an object.

Source: api.js, line 945

Returns:

The results of each statement

Type:: Array.<Database.QueryExecResult>

["export"]() → {Uint8Array}

Exports the contents of the database to a binary array. This operation will close and re-open the database which will cause any pragmas to be set back to their default values.

Source: api.js, line 1089

Returns:

An array of bytes of the SQLite3 database file

Type:: Uint8Array

["getRowsModified"]() → {number}

Returns the number of changed rows (modified, inserted or deleted) by the latest completed INSERT, UPDATE or DELETE statement on the database. Executing any other type of SQL statement does not modify the value returned by this function.

Source: api.js, line 1154

Returns:

the number of rows modified

Type:: number

["handleError"]()

Analyze a result code, return null if no error occured, and throw an error with a descriptive message otherwise

Source: api.js, line 1138

["iterateStatements"](sql) → {StatementIterator}

Iterate over multiple SQL statements in a SQL string. This function returns an iterator over Statement objects. You can use a for..of loop to execute the returned statements one by one.

Parameters:

Name	Type	Description
`sql`	string	a string of SQL that can contain multiple statements

Source: api.js, line 1080

Returns:

the resulting statement iterator

Type:: StatementIterator

Example

Get the results of multiple SQL queries

const sql_queries = "SELECT 1 AS x; SELECT '2' as y";
for (const statement of db.iterateStatements(sql_queries)) {
    const sql = statement.getSQL(); // Get the SQL source
    const result = statement.getAsObject({}); // Get the row of data
    console.log(sql, result);
}
// This will print:
// 'SELECT 1 AS x;' { x: 1 }
// " SELECT '2' as y" { y: '2' }

["prepare"](sql, paramsopt) → {Statement}

Prepare an SQL statement

Parameters:

Name	Type	Attributes	Description
`sql`	string		a string of SQL, that can contain placeholders (`?`, `:VVV`, `:AAA`, `@AAA`)
`params`	Statement.BindParams	<optional>	values to bind to placeholders

Source: api.js, line 1048

Throws:

SQLite error
Type String

Returns:

the resulting statement

Type:: Statement

["run"](sql, paramsopt) → {Database}

Execute an SQL query, ignoring the rows it returns.

Parameters:

Name	Type	Attributes	Description
`sql`	string		a string containing some SQL text to execute
`params`	Statement.BindParams	<optional>	When the SQL statement contains placeholders, you can pass them in here. They will be bound to the statement before it is executed. If you use the params argument, you cannot provide an sql string that contains several statements (separated by `;`)

Source: api.js, line 860

Returns:

The database object (useful for method chaining)

Type:: Database

Example

// Insert values in a table
    db.run(
        "INSERT INTO test VALUES (:age, :name)",
        { ':age' : 18, ':name' : 'John' }
    );

["updateHook"](callback) → {Database}

Registers an update hook with SQLite.

Every time a row is changed by whatever means, the callback is called once with the change ('insert', 'update' or 'delete'), the database name and table name where the change happened and the rowid of the row that has been changed.

The rowid is cast to a plain number. If it exceeds Number.MAX_SAFE_INTEGER (2^53 - 1), an error will be thrown.

Important notes:

The callback MUST NOT modify the database in any way
Only a single callback can be registered at a time
Unregister the callback by passing null
Not called for some updates like ON REPLACE CONFLICT and TRUNCATE (a DELETE FROM without a WHERE clause)

See SQLite documentation on sqlite3_update_hook for more details

Parameters:

Name	Type	Description
`callback`	Database~UpdateHookCallback \| null	Callback to be executed when a row changes. Takes the type of change, the name of the database, the name of the table, and the row id of the changed row. Set to `null` to unregister.

Source: api.js, line 1464

Returns:

The database object. Useful for method chaining

Type:: Database

Example

// Create a database and table
var db = new SQL.Database();
db.exec(`
CREATE TABLE users (
  id INTEGER PRIMARY KEY, -- this is the rowid column
  name TEXT,
  active INTEGER
)
`);

// Register an update hook
var changes = [];
db.updateHook(function(operation, database, table, rowId) {
  changes.push({operation, database, table, rowId});
  console.log(`${operation} on ${database}.${table} row ${rowId}`);
});

// Insert a row - triggers the update hook with 'insert'
db.run("INSERT INTO users VALUES (1, 'Alice', 1)");
// Logs: "insert on main.users row 1"

// Update a row - triggers the update hook with 'update'
db.run("UPDATE users SET active = 0 WHERE id = 1");
// Logs: "update on main.users row 1"

// Delete a row - triggers the update hook with 'delete'
db.run("DELETE FROM users WHERE id = 1");
// Logs: "delete on main.users row 1"

// Unregister the update hook
db.updateHook(null);

// This won't trigger any callback
db.run("INSERT INTO users VALUES (2, 'Bob', 1)");

Type Definitions

QueryExecResult

Type:

Object

Properties

Name	Type	Description
`columns`	Array.<string>	the name of the columns of the result (as returned by Statement.getColumnNames)
`values`	Array.<Array.<Database.SqlValue>>	one array per row, containing the column values

Source: api.js, line 877

SqlValue

Type:

string | number | null | Uint8Array

Source: api.js, line 286

UpdateHookCallback(operation, database, table, rowId)

Parameters:

Name	Type	Description
`operation`	'insert' \| 'update' \| 'delete'	The type of change that occurred
`database`	string	The name of the database where the change occurred
`table`	string	The name of the database's table where the change occurred
`rowId`	number	The rowid of the changed row

Source: api.js, line 1524