根据条件选择一列SQL Server

Question

我有这样的情况：

SELECT 
   fName, 
   lName
FROM employee as e
join payroll as p ON p.frn_employeeid = e.employeeId

对于employeeId = 2（WHERE e.employeeId = 2），我也想在select子句payCheck上添加另一列

 SELECT 
   fName, 
   lName,
   payCheck (this column should show on the report ONLY if employeeId = 2)
FROM employee as e
join payroll as p ON p.frn_employeeid = e.employeeId

感谢您为实现这一目标所提供的帮助。

注意：我知道我可以做的一件事是使用两个查询，然后检查employeeId = 2是否运行，假设查询1，否则运行查询2。 我正在寻找是否可以仅使用一个“ SMART”查询

Answer 1

案例陈述会给您您想要的：

SELECT fName, lName,
    CASE
        WHEN e.employeeid = 2
            THEN payCheck
        ELSE
            ''
    END AS Paycheck
FROM employee as e
    JOIN payroll as p ON p.frn_employeeid = e.employeeId

要完全排除该列，请使用IF THEN语句：

IF (employeeid = 2)
    SELECT fname, lname, paycheck
    FROM employee as e
        JOIN payroll as p ON p.frn_employeeid = e.employeeId
ELSE
    SELECT fname, lname
    FROM employee as e
        JOIN payroll as p ON p.frn_employeeid = e.employeeId