Pdo\Sqlite::createCollation
Registers a user-defined function for use as a collating function in SQL statements
Description
public bool Pdo\Sqlite::createCollation(string $name, callable $callback)
This method is similar to Pdo\Sqlite::createFunction
except that it registers functions that are used to collate strings.
Parameters
-
name
-
Name of the SQL collating function to be created or redefined.
-
callback
-
Callback function that defines the behaviour of a collation.
It must accept two strings and return
-1, 0, or 1
if the first string sorts before, sorts identically, or sorts after
the second string respectively.
An internal function that behaves like this is strcmp.
This function need to be defined as:
int collation(string $string1, string $string2)
Return Values
Returns true on success or false on failure.
Examples
Example #1 Pdo\Sqlite::createCollation example
<?php
$db = new Pdo\Sqlite('sqlite::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')");
$db->sqliteCreateCollation('NATURAL_CMP', 'strnatcmp');
foreach ($db->query("SELECT col1 FROM test ORDER BY col1") as $row) {
echo $row['col1'] . "\n";
}
echo "\n";
foreach ($db->query("SELECT col1 FROM test ORDER BY col1 COLLATE NATURAL_CMP") as $row) {
echo $row['col1'] . "\n";
}
?>
The above example will output:
See Also
- Pdo\Sqlite::createFunction
- Pdo\Sqlite::createAggregate
- sqlite_create_function
- sqlite_create_aggregate