Database

Database

Represents an SQLite database

Constructor

# new Database(data)

Parameters:
Name Type Description
data Array.<number>

An array of bytes representing an SQLite database file
Source:

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:

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

Register a custom aggregate with SQLite

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 Default Description
init function <optional>
 ()=>null

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>
 (state)=>state

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:
Returns:

The database object. Useful for method chaining

Type
Database
Example

Register a custom sum function

        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}

Register a custom function with SQLite

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:
Returns:

The database object. Useful for method chaining

Type
Database
Example

Register a simple function

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

# ["each"](sql, paramsopt, 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 Default 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:
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:
Returns:

The results of each statement

Type
Array.<Database.QueryExecResult>

# ["export"]() → {Uint8Array}

Exports the contents of the database to a binary array

Source:
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:
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:

# ["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:
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:
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:
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' }
    );

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:

# SqlValue

Type:
  • string | number | null | Uint8Array
Source: