get_meta_sql()

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概述

get_meta_sql() 函数基于给定的元查询参数，生成用于附加到主查询的 SQL 子句。它通过实例化 WP_Meta_Query 类并调用其 get_sql() 方法来实现，返回包含 JOIN 和 WHERE 子句的数组。

关键要点

函数接受元查询数组、元类型、主表名、主ID列名和可选上下文对象作为参数。
返回一个数组，包含 'join' 和 'where' 键，分别对应 SQL 的 JOIN 和 WHERE 子句片段，若元类型无对应表则返回 false。
内部依赖于 WP_Meta_Query 类，适用于处理 WordPress 中的自定义字段查询。

代码示例

$meta_query = array(
    array(
        'key' => 'color',
        'value' => 'blue',
        'compare' => 'NOT LIKE'
    )
);
global $wpdb;
$meta_sql = get_meta_sql( $meta_query, 'post', $wpdb->posts, 'ID' );
// 输出示例：
// Array
// (
//     [join] =>  INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id)
//     [where] =>  AND ( (wp_postmeta.meta_key = 'color' AND CAST(wp_postmeta.meta_value AS CHAR) NOT LIKE '%blue%') )
// )

📄 原文内容

Given a meta query, generates SQL clauses to be appended to a main query.

Description

Parameters

$meta_queryarrayrequired: A meta query.
$typestringrequired: Type of meta.
$primary_tablestringrequired: Primary database table name.
$primary_id_columnstringrequired: Primary ID column name.
$contextobjectoptional: The main query object.

Default:null

Return

string[]|false Array containing JOIN and WHERE SQL clauses to append to the main query, or false if no table exists for the requested meta type.

join string
SQL fragment to append to the main JOIN clause.
where string
SQL fragment to append to the main WHERE clause.

Source

function get_meta_sql( $meta_query, $type, $primary_table, $primary_id_column, $context = null ) {
	$meta_query_obj = new WP_Meta_Query( $meta_query );
	return $meta_query_obj->get_sql( $type, $primary_table, $primary_id_column, $context );
}

View all references View on Trac View on GitHub

Uses	Description
WP_Meta_Query::__construct()`wp-includes/class-wp-meta-query.php`	Constructor.

Changelog

Version	Description
3.2.0	Introduced.

User Contributed Notes

Skip to note 2 content

Codex

10 years ago

Example

 'color',
		'value' => 'blue',
		'compare' => 'NOT LIKE'
	)
);
global $wpdb;
$meta_sql = get_meta_sql( $meta_query, 'post', $wpdb->posts, 'ID' );

Output depending on the meta query:

Array
(
    [join] =>  INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id)
    [where] =>  AND ( (wp_postmeta.meta_key = 'color' AND CAST(wp_postmeta.meta_value AS CHAR) NOT LIKE '%blue%') )
)

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