Question

我有以下SQL代码：

SELECT eml AS "Email Address"
FROM emailtbl
WHERE DEPT LIKE 'E%'

我的问题是如果部门以'F'开头，我必须选择传真而不是eml。如果部门以“E”开头则选择eml，如果部门以“F”开头则选择传真

由于

Answer 1

一种选择是使用UNION ALL声明

SELECT eml AS "Entity"
FROM   emailtbl
WHERE  DEPT LIKE 'E%'
UNION ALL
SELECT fax AS "Entity"
FROM   emailtbl
WHERE  DEPT LIKE 'F%'

另一个是使用CASE语句

SELECT CASE WHEN Dept LIKE 'E%' THEN eml ELSE fax END AS "Entity"
FROM   emailtbl
WHERE  DEPT LIKE 'E%' OR DEPT LIKE 'F%'

Answer 2

这个怎么样？

IF (SUBSTRING(@useLike,1,1) = 'E')
BEGIN
    SELECT eml AS "Email Address"
    FROM emailtbl
    WHERE DEPT LIKE @useLike

END
ELSE
BEGIN
    SELECT fax AS "Email Address"
    FROM emailtbl
    WHERE DEPT LIKE @useLike
END

SQL中的条件选择？

2 个答案: