Registers a PHP function for use as an SQL collating function

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- Registers a PHP function for use as an SQL collating function

# SQLite3::createCollation

(PHP 5 >= 5.3.11, PHP 7, PHP 8)

SQLite3::createCollation — Registers a PHP function for use as an SQL collating function

### Description

public SQLite3::createCollation(string `$name`, callable `$callback`): bool

Registers a PHP function or user-defined function for use as a collating function within SQL statements.

### Parameters

`name`

  Name of the SQL collating function to be created or redefined

`callback`

  The name of a PHP function or user-defined function to apply as a callback, defining the behavior of the collation. It should accept two values and return as strcmp() does, i.e. it should return -1, 1, or 0 if the first string sorts before, sorts after, or is equal to the second.

  This function need to be defined as:

  collation(mixed `$value1`, mixed `$value2`): int

### Return Values

Returns `true` on success or `false` on failure.

### Examples

Example #1 SQLite3::createCollation() example

Register the PHP function strnatcmp() as a collating sequence in the SQLite3 database.

    <?php$db = new SQLite3(":memory:");$db->exec("CREATE TABLE test (col1 string)");$db->exec("INSERT INTO test VALUES ('a1')");$db->exec("INSERT INTO test VALUES ('a10')");$db->exec("INSERT INTO test VALUES ('a2')");$db->createCollation('NATURAL_CMP', 'strnatcmp');$defaultSort = $db->query("SELECT col1 FROM test ORDER BY col1");$naturalSort = $db->query("SELECT col1 FROM test ORDER BY col1 COLLATE NATURAL_CMP");echo "default:\n";while ($row = $defaultSort->fetchArray()){    echo $row['col1'], "\n";}echo "\nnatural:\n";while ($row = $naturalSort->fetchArray()){    echo $row['col1'], "\n";}$db->close();?>

The above example will output:

    default:
    a1
    a10
    a2

    natural:
    a1
    a2
    a10

### See Also

- The SQLite collation documentation: » http://sqlite.org/datatype3.html#collation