如何將table2從table1更新到table2中的相應條目？

Question

我想計算不同表中存儲庫的出現，並在FinalTable的相應列中進行更新。

銀行表格：

  BankName  ErrorCode
    SBI         200
    ICICI       200
    SBI         400
    SBI         500
    SBI         503

ATMTable：

BankName    ErrorCode
ICICI       200
ICICI       400
ICICI       400
SBI         500
SBI         503

MitraTable：

BankName    ErrorCode
ICICI        200
ICICI        200
SBI          400
SBI          500
SBI          503
PNB          501  

決賽桌：

BankName    BankCount   ATMCount    MitraCount  TotalCount
ICICI            1         3           2          6
SBI              4         2           3          9
PNB              0         0           1          1

我想計算不同銀行的出現次數，並在FinalTable中設置值。

Answer 1

您可以將UNION ALL與條件聚合一起使用：

SELECT BankName,
       COUNT(CASE WHEN src = 'Bank' THEN 1 END) AS BankCount,
       COUNT(CASE WHEN src = 'ATM' THEN 1 END) AS ATMCount,
       COUNT(CASE WHEN src = 'Mitra' THEN 1 END) AS MitraCount,
       COUNT(*) AS TotalCount

FROM (
   SELECT BankName, 'Bank' AS src 
   FROM BankTable

   UNION ALL 

   SELECT BankName, 'ATM' AS src
   FROM ATMTable

   UNION ALL

   SELECT BankName, 'Mitra' AS src
   FROM MitraTable) AS t
GROUP BY BankName

字段src用於將源表返回到使用UNION ALL操作結果的外部查詢。 使用此字段，我們可以執行條件聚合 ，以便計算每個源表中每個存儲庫的出現。

Answer 2

嘗試這個：

SELECT BankName, 
       SUM(BankCount) AS BankCount, 
       SUM(ATMCount) AS ATMCount, 
       SUM(MitraCount) AS MitraCount, 
       SUM(BankCount + ATMCount + MitraCount) AS TotalCount 
FROM (SELECT BankName, 
             COUNT(ErrorCode) AS BankCount, 
             0 AS ATMCount, 
             0 AS MitraCount 
      FROM BankTable 
      GROUP BY BankName 
     UNION 
      SELECT BankName, 
             0 AS BankCount, 
             COUNT(ErrorCode) AS ATMCount, 
             0 AS MitraCount 
      FROM ATMTable 
      GROUP BY BankName 
     UNION 
      SELECT BankName, 
             0 AS BankCount, 
             0 AS ATMCount, 
             COUNT(ErrorCode) AS MitraCount 
      FROM MitraTable 
      GROUP BY BankName
    ) AS A
GROUP BY BankName;