Question

    CREATE TRIGGER [dbo].[TR_dbo_GlLoan_LoanNumber] ON  [dbo].[GlLoan] AFTER     INSERT 
AS 
BEGIN 
 if @@ROWCOUNT = 0
  return
SET NOCOUNT ON;

declare @count int; 
set @count= (select max(loannumber) from glloan where branchid=(select branchid from inserted) and CompanyId=(select CompanyId from inserted)) 
update glloan set loannumber=@count+1 where id=(select id from inserted) 
END

GO

是否有可能为某个分支机构和公司重复贷款编号？

Answer 1

从我的评论中 - 如果我们可以安全地假设没有删除任何行，我会改为创建这个结构：

CREATE TABLE _GILoan (
    /* Columns as currently, except no loannumber column */
    _Id int IDENTITY(1,1) not null /* or is Id already defined so? */
)
GO
CREATE VIEW GILoan
AS
    SELECT
        *,
        ROW_NUMBER() OVER (PARTITION BY branchid,companyid
          ORDER BY _Id) /* Or Id */
        as LoanNumber
    FROM _GILoan
GO

然后以与使用表格相同的方式处理此视图。 LoanNumber是自动计算的（如我所说），如果没有删除任何行，则分配的数字不会改变。

Answer 2

我们可以添加多列的唯一约束。

    ALTER TABLE dbo.glloan 
    ADD CONSTRAINT ucLoanNumber UNIQUE (BranchId, CompanyId, LoanNumber)

在插入触发器之前使用计算贷款数量。因此，任何重复项都不会被插入。

“插入触发器” - 插入后更新列

2 个答案: