sql-添加子查詢的查詢語法問題

Question

我似乎無法在沒有任何語法錯誤的情況下執行此查詢，但出現以下錯誤：

無法綁定多部分標識符“ TBL1.Avg_CycleTime”。

查詢：

SELECT (AVG(TBL1.Avg_CycleTime + TBL4.Avg_GRM_CycleTime)) AS Overall_Renewals_CycleTime
FROM (
    SELECT *
    FROM (
        SELECT AVG(1.00 * Avg_DayDiff) AS Avg_CycleTime
        FROM (
            SELECT AVG(1.00 * DATEDIFF(DAY, yy, xx)) AS Avg_DayDiff
            FROM Database1.dbo.tbl_1
            WHERE month(datecompleted) = month(dateadd(month, - 1, current_timestamp))
                AND year(datecompleted) = year(dateadd(month, - 1, current_timestamp))
            ) t1
        WHERE Avg_DayDiff > 0
        ) TBL1
    CROSS JOIN (
        SELECT *
        FROM (
            SELECT AVG(1.00 * Avg_DayDiff) AS Avg_GRM_CycleTime
            FROM (
                SELECT DATEDIFF(DAY, xx, uu) AS Avg_DayDiff
                FROM Database1.dbo.tbl_1
                WHERE month(datecompleted) = month(dateadd(month, - 1, current_timestamp))
                    AND year(datecompleted) = year(dateadd(month, - 1, current_timestamp))
                    AND ApprovalRequiredFrom = 'GRM'
                ) t2
            WHERE Avg_DayDiff > 0
            ) TBL2
        ) TBL3
    ) TBL4

有人可以告訴我我做錯了嗎？ 我想獲得（Avg_cycletime和avg_grm_cycletime）之間的平均值

干杯，

Answer 1

-在選擇中，您正在從TBL1中選擇值（子查詢中FROM中不存在的值。將其更改為TBL4

select (AVG(TBL1.Avg_CycleTime + TBL4.Avg_GRM_CycleTime)) as Overall_Renewals_CycleTime
from ()
  )TBL4

另外，我不會使用太多嵌套選擇，或者至少不會使用Select *（選擇*絕不是好主意）。