Question

我有以下SQL Server查询：

SELECT 
    @alloweddays as alloweddays,
    @prevalloweddays as prevalloweddays,
    ISNULL(COUNT(0),0) as useddays,
    CASE WHEN COUNT(0) > @alloweddays THEN COUNT(0) - @alloweddays ELSE 0 END as daysinadvance,
    CASE WHEN @alloweddays > COUNT(0) THEN @alloweddays - COUNT(0) ELSE 0 END as remainingdays,
    temp.prevremainingdays
FROM 
    employee_holiday_item hi
JOIN
    (SELECT 
        CASE WHEN @prevalloweddays > COUNT(0) THEN @prevalloweddays - COUNT(0) ELSE 0 END as prevremainingdays,
        hi.employeeid
     FROM 
        employee_holiday_item hi
     WHERE 
        hi.employeeid = 351
        AND hi.isactive = 1
        AND hi.date BETWEEN @prevstartperiod AND @prevendperiod
     GROUP BY 
        hi.employeeid) temp ON temp.employeeid = hi.employeeid
WHERE 
   hi.employeeid = 351
   AND hi.isactive = 1
   AND hi.date BETWEEN @startperiod AND @endperiod
GROUP BY 
   temp.prevremainingdays

如果第一个选择中没有记录，则不返回任何记录，但我希望至少获得JOIN个选择记录。

此查询获取员工在实际年份中请求的假期。联接获取上一期间的未使用天数，因此如果员工在实际年份中没有假期请求，我希望至少看到上一期间的未使用天数。

我正在考虑进行2次完全单独的选择，然后只做UNION ALL，但不知道它是否是最好的方法。

有任何线索吗？

Answer 1

更改

...
FROM employee_holiday_item hi
JOIN(
SELECT
    CASE WHEN @prevalloweddays ...

到

...
FROM employee_holiday_item hi
RIGHT OUTER JOIN(
SELECT
    CASE WHEN @prevalloweddays ...

这就是说＆＃34;从JOIN的右侧拿走所有内容，无论如何都返回...如果JOIN左侧返回结果，则返回它们＆＃34;

SQL Query如果没有记录返回连接记录

1 个答案: