Pdo\Sqlite::createCollation

(PHP 8 >= 8.4.0)

Pdo\Sqlite::createCollation — Registers a user-defined function for use as a collating function in SQL statements

说明

public Pdo\Sqlite::createCollation(string $name, callable $callback): bool

This method is similar to Pdo\Sqlite::createFunction() except that it registers functions that are used to collate strings.

参数

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:
collation(string $string1, string $string2): int

返回值

成功时返回 true，或者在失败时返回 false。

示例

示例 #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";
}
?>

以上示例会输出：

a1
a10
a2

a1
a2
a10

参见

Pdo\Sqlite::createFunction() - Registers a user-defined function for use in SQL statements
Pdo\Sqlite::createAggregate() - Registers an aggregating user-defined function for use in SQL statements
sqlite_create_function()
sqlite_create_aggregate()

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