帶有計數的SQL LEFT OUTER JOIN

Question

我在這里有此查詢：

SELECT a.timeSlot, a.dateSlot, COUNT(concat(b.dateSlot, ' - ', b.timeSlot)) AS counter 
FROM CP_VIP_Preview_TimeSlots as a 
   LEFT OUTER JOIN [CP-VIP-Preview] as b 
                ON a.timeSlot = b.dateSlot 
               AND a.dateSlot = b.timeSlot 
GROUP BY a.timeSlot, a.dateSlot, a.[order] 
ORDER BY a.[order]

我想做的是獲取每個查詢的計數，但是查詢有些混亂，任何具有0的行都顯示為1，而實際上具有項目的任何行都顯示正確的數字，如果該行存在問題count是0，它顯示1.。為什么這樣做？

Answer 1

您的COUNT(concat(b.dateSlot, ' - ', b.timeSlot))將始終返回至少一個

也許你可以嘗試

sum(IIF(b.dateSlot is null,0,1))

Answer 2

您需要使用HAVING在使用分組依據之后應用過濾器，這樣就不會將記錄計數為零

SELECT a.timeSlot, a.dateSlot, COUNT(concat(b.dateSlot, ' - ', b.timeSlot)) AS counter 
FROM CP_VIP_Preview_TimeSlots as a 
   LEFT OUTER JOIN [CP-VIP-Preview] as b 
                ON a.timeSlot = b.dateSlot 
               AND a.dateSlot = b.timeSlot 
GROUP BY a.timeSlot, a.dateSlot, a.[order] 
ORDER BY a.[order]

HAVING COUNT（concat（b.dateSlot，'-'，b.timeSlot））> 0