Question

我想用给定的参数值执行两个不同的mysql查询。

这是我的疑问：

select Gender, count(EmployeeId) as NoOfEmployees 
from people_HR.PEOPLE_HR
where EmploymentType = 'INTERNSHIP' and ((StartDate < '2006-07-01' AND EmployeeStatus = 'Active') OR (EmployeeStatus = 'Left' AND '2006-07-01' <= FinalDayofEmployment AND StartDate < '2006-07-01' )) and Gender<>'' group by Gender

此就业类型和日期将被指定为参数。如果EmploymentType ='Total'，我需要为整个表运行查询。如何通过mysql查询实现这一目标？

注意：下面的代码作为我需要实现的伪代码。

if (EmploymentType = 'Total') 
select Gender, count(EmployeeId) as NoOfEmployees 
from people_HR.PEOPLE_HR
where ((StartDate < '2006-07-01' AND EmployeeStatus = 'Active') OR (EmployeeStatus = 'Left' AND '2006-07-01' <= FinalDayofEmployment AND StartDate < '2006-07-01' )) and Gender<>'' group by Gender

else
select Gender, count(EmployeeId) as NoOfEmployees 
from people_HR.PEOPLE_HR
where EmploymentType = 'INTERNSHIP' and ((StartDate < '2006-07-01' AND EmployeeStatus = 'Active') OR (EmployeeStatus = 'Left' AND '2006-07-01' <= FinalDayofEmployment AND StartDate < '2006-07-01' )) and Gender<>''group by Gender

对此表示高度赞赏的任何帮助。

注意：这不是存储过程。因此不能直接使用“IF”，我需要通过“select if”来实现。

Answer 1

    IF (@EmploymentType = 'Total') THEN

           select Gender, count(EmployeeId) as NoOfEmployees 
           from people_HR.PEOPLE_HR
           where ((StartDate < '2006-07-01' AND EmployeeStatus = 'Active') OR (EmployeeStatus = 'Left' AND '2006-07-01' <= FinalDayofEmployment AND StartDate < '2006-07-01' )) and Gender<>'' group by Gender


     ELSE

          select Gender, count(EmployeeId) as NoOfEmployees 
          from people_HR.PEOPLE_HR
          where EmploymentType = 'INTERNSHIP' and ((StartDate < '2006-07-01' AND EmployeeStatus = 'Active') OR (EmployeeStatus = 'Left' AND '2006-07-01' <= FinalDayofEmployment AND StartDate < '2006-07-01' )) and Gender<>''group by Gender

    END IF

顺便说一下，你只能在存储过程或函数中使用if语句。

Answer 2

您可以在此方案中使用CASE语句。这将适用于SQL查询。

    select Gender, count(EmployeeId) as NoOfEmployees 
    from people_HR.PEOPLE_HR
    where
    CASE WHEN @EmploymentType = 'TOTAL' THEN 
    EmploymentType<>''
    ELSE 
    EmploymentType=@EmploymentType
    END 
    and ((StartDate < '2006-07-01' AND EmployeeStatus = 'Active') OR (EmployeeStatus = 'Left' AND '2006-07-01' <= FinalDayofEmployment AND StartDate < '2006-07-01' )) and Gender<>''group by Gender

Answer 3

IF (@EmploymentType = 'Total')
BEGIN
   select Gender, count(EmployeeId) as NoOfEmployees 
   from people_HR.PEOPLE_HR
   where ((StartDate < '2006-07-01' AND EmployeeStatus = 'Active') OR (EmployeeStatus = 'Left' AND '2006-07-01' <= FinalDayofEmployment AND StartDate < '2006-07-01' )) and Gender<>'' group by Gender
END

ELSE
BEGIN
  select Gender, count(EmployeeId) as NoOfEmployees 
  from people_HR.PEOPLE_HR
  where EmploymentType = 'INTERNSHIP' and ((StartDate < '2006-07-01' AND EmployeeStatus = 'Active') OR (EmployeeStatus = 'Left' AND '2006-07-01' <= FinalDayofEmployment AND StartDate < '2006-07-01' )) and Gender<>''group by Gender
END

mysql if else用于选择正确的查询

3 个答案: