Question

我想从表1中选择所有行。在column1或column2和状态1中有smith。
如果第1列中有smith，则从第2列中选择值，如果第2列中有smith，则在行的第1列中选择值。
然后选择表2中的所有行，其中包含表2的column1或column2中的值（我们通过从表1中选择得到的。）

Answer 1

这应该涵盖＃1/2，你已经失去了＃3

select if(col1 = 'smith', col2, col1) from table1 
where (col1 = 'smith' or col2 = 'smith') and status = 1

Answer 2

与Ben的查询

select * from table2
where column1 in (select if(column1 = 'smith', column2, column1) from table1 where (column1 = 'smith' or column2 = 'smith') and status = 1)
OR
column2 in (select if(column1 = 'smith', column2, column1) from table1 where (column1 = 'smith' or column2 = 'smith') and status = 1)

OR

select * from table2 where
column1 in (select column1 from table1 where column2 = 'Smith' AND status = 1) OR 
column1 in (select column2 from table1 where column1 = 'Smith' AND status = 1) OR 
column2 in (select column1 from table1 where column2 = 'Smith' AND status = 1) OR 
column2 in (select column2 from table1 where column1 = 'Smith' AND status = 1)

Answer 3

select * 
  from  table1 as t1, table2 as t2
 where t1.status = 1
   and (t1.col1 = 'smith' and (t2.col1 = t1.col2 or t2.col2 = t1.col2)
       or t1.col2 = 'smith' and (t2.col1 = t1.col1 or t2.col2 = t1.col1))

Answer 4

可能最好的解决方案是重新设计数据库，但如果你真的想保留你的表，你可以尝试这个查询：

SELECT IF(t1.col1 = 'smith', t1.col2, t1.col1) AS t1col2,  IF(t2.col1 = t1col2, t2.col2, t2.col1) AS t2col2
FROM table1 AS t1
JOIN table2 AS t2 ON( IF(t1.col1 = 'smith', t1.col2, t1.col1) IN ( t2.col1, t2.col2 ) )
WHERE (t1.col1 = 'smith' OR t1.col2 = 'smith') AND t1.status = 1

Answer 5

这样的事情可能就是你所追求的......

SELECT *
    FROM table_1
    WHERE col_1 LIKE '%smith%' AND status = 1

UNION DISTINCT

SELECT *
    FROM table_1
    WHERE col_2 LIKE '%smith%' AND status = 1

UNION

    SELECT *
        FROM table_2
        WHERE ...er...

此时我不能理解这个问题，因为问题1和问题2的回报不是值而是结果集。但它可以继续......

WHERE col_1 IN (SELECT col_1
                    FROM table_1
                    WHERE col_1 LIKE '%smith%' AND status = 1
                  UNION
                SELECT col_2
                    FROM table_1
                    WHERE col_2 LIKE '%smith%' AND status = 1);

带选择的mysql复杂查询

5 个答案: