如何将这些查询整合到一个查询中？

Question

好吧，我再试一次……这次我绝对做对了。很抱歉造成混乱。 :(

table1:

+----+---------+------------+------+
| id | item_id | product_id | type |
+----+---------+------------+------+

table2, table3, table4:

+----+---------+
| id | item_id |
+----+---------+

这是我的主要查询：

$sql = "SELECT t1.* FROM table1 AS t1, table2 AS t2 WHERE t2.id = '1' AND 
t2.item_id = t1.item_id AND t1.type NOT IN ('type1', 'type2') LIMIT 5";

$a = mysql_query($sql);
while($b = mysql_fetch_assoc($a))

现在我想集成这 2 个查询< /strong>:

第一个查询:

AND IF t1.type = 'type3' THEN

SELECT t3.item_id FROM table3 AS t3 WHERE t3.id = t1.product_id AND
t3.item_id NOT IN (SELECT t2.item_id FROM table2 AS t2 WHERE t2.id = '1')

仅当此语句t3.item_id NOT IN (...) 是true，则应显示主查询中的t1.id，但是，如果t3.item_id is IN (...)，则应显示。应从结果中排除

第二个查询：

AND IF t1.type = 'type4' THEN

SELECT t4.item_id FROM table4 AS t4 WHERE t4.id = t1.product_id AND
t4.item_id NOT IN (SELECT t2.item_id FROM table2 AS t2 WHERE t2.id = '1')

第一个查询相同。

与 全部适合一个查询吗？我需要它在一个查询中只是，所以我知道下一页上显示哪些结果，例如 LIMIT 5,5

Answer 1

我不确定我理解是否正确，但我认为应该使用 (NOT) EXISTS ：

SELECT t1.* 
FROM table1 AS t1
  JOIN table2 AS t2 
    ON t2.item_id = t1.item_id
WHERE t2.id = '1' 
  AND t1.type NOT IN ('type1', 'type2')
  AND NOT ( t1.type = 'type3' 
            AND EXISTS 
                ( SELECT t3.item_id
                  FROM table3 AS t3
                  WHERE t3.id = t1.product_id
                    AND t3.item_id NOT IN
                          ( SELECT t2.item_id 
                            FROM table2 AS t2
                            WHERE t2.id = '1' )
                )
           ) 
  AND NOT ( t1.type = 'type4' 
            AND EXISTS 
                ( SELECT t4.item_id
                  FROM table4 AS t4
                  WHERE t4.id = t1.product_id
                    AND t4.item_id NOT IN
                          ( SELECT t2.item_id 
                            FROM table2 AS t2
                            WHERE t2.id = '1' )
                )
           ) 
ORDER BY WhatYouWant
LIMIT x,y

Answer 2

应用流控制流结构 在 mysql 中

CASE case_value
    WHEN when_value THEN statement_list
    [WHEN when_value THEN statement_list] ...
    [ELSE statement_list]
END CASE

或者：

CASE
    WHEN search_condition THEN statement_list
    [WHEN search_condition THEN statement_list] ...
    [ELSE statement_list]
END CASE