为什么 EXCEPT 功能不起作用？

Question

我有 mysql 如下查询：

$missingTypo = mysql_query("SELECT m.ID
                              FROM table1 AS m
                              LEFT JOIN table2 AS ut
                              ON ut.matchID = m.ID
                              WHERE data > '$now'
                          EXCEPT
                            SELECT m.ID
                              FROM table1 AS m
                              LEFT JOIN table2 AS ut
                              ON ut.matchID = m.ID
                              WHERE data > '$now' 
                              AND ut.typer = '$name'");

第一个状态查询returns 3 个结果[10,11,12]，第二个return1 个结果[10]。整个查询的结果应该是 [11, 12] 但它不起作用。 var_dump 函数 return 错误。但是，如果我将 "EXCEPT" 交换为例如 "UNION ALL" 它工作正常并给出 [10, 11, 12, 10].

请帮忙。

Answer 1

MySQL 不支持 EXCEPT，请改用 WHERE NOT

Answer 2

正如其他答案所建议的那样，Mysql 不支持 EXCEPT，但您可以使用 NOT IN 谓词：

SELECT m.ID
FROM table1 AS m
LEFT JOIN table2 AS ut ON ut.matchID = m.ID
WHERE data > '$now'
  AND m.ID NOT IN(SELECT m2.ID
                  FROM table1 AS m2
                  INNER JOIN table2 AS ut ON ut.matchID = m.ID
                  WHERE data > '$now' 
                    AND ut.typer = '$name');

或LEFT JOIN:

SELECT t1.ID
FROM
(
  SELECT m.ID
  FROM table1 AS m
  LEFT JOIN table2 AS ut ON ut.matchID = m.ID
  WHERE data > '$now'
) AS t1
LEFT JOIN
(
  SELECT m.ID
  FROM table1 AS m
  LEFT JOIN table2 AS ut ON ut.matchID = m.ID
  WHERE data > '$now' 
    AND ut.typer = '$name'
) AS t2 ON t1.ID = t2.ID
WHERE t2.ID IS NULL

为什么 EXCEPT 功能不起作用？

Why EXCEPT function doesn't work?

php

mysql

except