Question

我写了一个如下查询，但收到错误

SELECT DISTINCT T2.host, 
 T3.error
FROM table1 T1
INNER JOIN table2 T2
ON
T1.item_id = T2.item_id
INNER JOIN table3 T3
ON
T1.ID = T3.run_id 
and T1.submit_id = (select max(T1.submit_id) from table1 T1) 
;

此处T3.run_id = (select max(T3.run_id) from T3)发出错误

对于特定T3

，max(T3.run_id)的{{1}}有三行

T1.item_id = T2.item_id

以上是item_id host 15907 abc.com 7303 cde.com 7304 abcd.com 7305 cdedf.com的示例数据 table 2

select * from table2 where item_id = '15907';

以上是id submit_id item_id 49898 16693 15907 49899 16693 15907 49900 16693 15907 53735 17972 15907 53736 17972 15907 53737 17972 15907的示例数据 table 1

上面我需要选择select * from table1 where item_id = '15907';和max(submit_id)的行在此示例中，它将是T1.item_id = T2.item_id

以上是id run_id error 12345 53735 error1 12345 53735 error2 12346 53735 error3 12347 53736 error4 12348 53736 error5 12349 53737 error6的示例数据 table3

我得到0行作为输出

Answer 1

您可以按如下所述重写查询以获得预期的输出

SELECT DISTINCT T2.host,T3.error
FROM table2 T2
INNER JOIN (
    SELECT a.*
    FROM table1 a
    LEFT JOIN table1 b ON a.item_id = b.item_id AND a.submit_id < b.submit_id
    WHERE b.submit_id IS NULL
) T1  ON T1.item_id = T2.item_id
INNER JOIN table3 T3 ON T1.ID = T3.run_id

我已在内部查询中移动了table1以获取submit_id最大值

的ID

DEMO

Answer 2

检查下面的输出

SELECT DISTINCT T2.host 
     ,T3.error
    FROM table1 T1
    INNER JOIN table2  T2 ON T1.item_id = T2.item_id
    and T1.submit_id = (select max(T1.submit_id) from table1  T1 )
    INNER JOIN table3 T3 ON T1.ID = T3.run_id 
    ;

输出

host    error
abc.com error1
abc.com error2
abc.com error3
abc.com error4
abc.com error5
abc.com error6

MYSQL第三个内连接不起作用

2 个答案: