MySQL多重查询＆gt;将行存储到列中

Question

我需要创建一个列出以下表的SQL查询。语言列表中的行作为列名。感谢

图片表和查询：

Answer 1

如果预先知道语言

SELECT r.id, r.parent,
       MAX(CASE WHEN n.language_id = 1 THEN n.name END) cs,
       MAX(CASE WHEN n.language_id = 2 THEN n.name END) en
  FROM cat_route r LEFT JOIN cat_route_name n
    ON r.id = n.cat_route_id
 GROUP BY r.id

这是 SQLFiddle 演示

---

如果您希望它是动态的，具体取决于您在language

中定义的语言

SET @sql = NULL;

SELECT GROUP_CONCAT(CONCAT(
  'MAX(CASE WHEN n.language_id = ', id, ' THEN n.name END) `', short, '`'))
  INTO @sql
  FROM language;

SET @sql = CONCAT(
  'SELECT r.id, r.parent, ', @sql, '
     FROM cat_route r LEFT JOIN cat_route_name n
       ON r.id = n.cat_route_id
    GROUP BY r.id');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

这是 SQLFiddle 演示