Question

无论如何都要优化以下查询：

SELECT
  t1.id,
  (SELECT SUM(col1) FROM table_name_two t2 WHERE t2.name LIKE CONCAT('%',t1.name)) AS col1_count
FROM
  table_name_one t1
ORDER BY 
  col1_count DESC

使用ORDER BY col1_count DESC需要很长时间。

感谢。

Answer 1

只需在连接的on子句中进行正常连接：

SELECT
  t1.id,
  SUM(t2.col1) AS col1_count
FROM table_name_one t1
LEFT JOIN table_name_two t2 on t2.name LIKE CONCAT('%', t1.name)
GROUP BY 1
ORDER BY 2 DESC

它应该以这种方式方式 - 它基本上是一个查询而不是“n”查询，尽管它不会从使用LIKE运算符的索引获得任何帮助%

MySQL将子查询SUM（）ORDER BY相关联

1 个答案: