Pdo\Sqlite::createCollation

Registers a user-defined function for use as a collating function in SQL statements

説明

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.

パラメータ

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)

戻り値

成功した場合に true を、失敗した場合に false を返します。

例

例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";
}
?>

上の例の出力は以下となります。

a1
a10
a2

a1
a2
a10

参考

Pdo\Sqlite::createFunction
Pdo\Sqlite::createAggregate
sqlite_create_function
sqlite_create_aggregate