考虑租户ID的自动增量

Question

我使用的是SQL Server，需要根据租户ID保留一个会计编号。

我无法使用自动增量ID，因为它是按顺序递增的，并且在客户端应用程序中存在间隙。

我无法使用计算列作为ArrayList<String> EnglishCategorie = new ArrayList<String>(); EnglishCategorie.add("HarryPotter"); boolean repeatAgain = true; while(repeatAgain) { System.out.println("Please choose an option (between 1 and 5) :"); System.out.println("Press 1 to search a book in English Categorie. System.out.println("Press 2 to exit the program. "); "); int choice = input.nextInt(); switch (choice) { case 1: System.out.println("Please enter a book name: "); bookName = input.nextLine(); if(bookName == EnglishCategorie.contains("HarryPotter") ) System.out.println("It is available."); else System.out.println("It is not available."); break; 之类的聚合函数

最好的办法是什么？

Answer 1

您还可以在插入数据时进行处理，例如：

insert into table1(ID,TenantId,PaymentId)
select 6,2,isnull(max(PaymentId)+1,1)
from table1 where TenantId=2 
group by TenantId

如果你想使用触发器，这是一个示例，在该示例中，即使您在插入数据时指定了PaymentId，此触发器也会重新计算PaymentId

    DROP TABLE table1
    CREATE TABLE Table1(ID INT IDENTITY(1,1),TenantId INT ,PaymentId INT)

    CREATE TRIGGER trg_UpdatePaymentId 
       ON  dbo.TABLE1
       AFTER INSERT
    AS 
    BEGIN

        SET NOCOUNT ON;

        UPDATE t SET t.PaymentId=a.rn
        FROM dbo.TABLE1 AS t INNER JOIN (
            SELECT i.ID,(ISNULL(c.MaxPaymentId,0)+ ROW_NUMBER()OVER(PARTITION BY TenantId ORDER BY ID)) AS rn FROM Inserted AS i
            OUTER APPLY(
                SELECT MAX(tt.PaymentId) AS MaxPaymentId FROM Table1 AS tt WHERE tt.TenantId=i.TenantId AND NOT EXISTS(SELECT 0 FROM Inserted AS ii WHERE ii.ID=tt.ID)
            ) AS c
        ) AS a ON a.ID=t.ID 


    END
    GO


    INSERT INTO table1(TenantId)VALUES(1),(2),(1),(1)
    SELECT * FROM dbo.TABLE1

ID          TenantId    PaymentId
----------- ----------- -----------
1           1           1
2           2           1
3           1           2
4           1           3