SQL查询来选择某些行

Question

我有一个表下方

+++++++++++++++++++++++++ 
colA | colB | colC | colD 
+++++++++++++++++++++++++ 
1 | female | ... | ... 
2 | male | ... | ... 
3 |  | ... | ... 
4 | select | ... | ... 
5 | dfd | ... | ... 
+++++++++++++++++++++++++ 

给出我想选择与COLB“女性”或“男性”的所有行，也行空或“选择” colB中的值，但想将其重命名为“未知”。结果表应该是：

+++++++++++++++++++++++++ 
colA | colB | colC | colD 
+++++++++++++++++++++++++ 
1 | female | ... | ... 
2 | male | ... | ... 
3 | unknown| ... | ... 
4 | uknown | ... | ... 
+++++++++++++++++++++++++ 

我的查询语句：

SELECT colA, colB, colC, colD FROM table 
where (colB in ('female','male') and 
     case when colB = '' then 'unknown' 
      when colB = 'select' then 'unknown' end) 

Answer 1

你似乎想：​​

SELECT colA, 
     (CASE WHEN colB IN ('female', 'male') THEN colb ELSE 'unknown' END) as colB, 
     colC, colD 
FROM table 
WHERE colB in ('female', 'male', '') OR colB IS NULL; 

Answer 2

所以，你想有四个值的行，但你要以不同的方式呈现两种情况。

更改值的显示应该在选择列表中完成。

SELECT colA, 
    CASE WHEN colB IN ('','select') THEN 'unknown' ELSE colB END AS colB,  
    colC, colD 
FROM table 
WHERE colB IN ('','select','female','male');