如果有条件，则 upsert else 什么都不做

Question

我试图仅在条件为真时才插入值，否则我不想对记录执行任何操作。当我再次运行时，我的代码似乎会生成主键错误（表明插入正在触发，但应跳过整个语句）

第二个错误运行：Violation of PRIMARY KEY constraint 'PK__chicken__A2D9E564407C90CD'. Cannot insert duplicate key in object 'dbo.chicken'. The duplicate key value is (10118-78843).

查询：

IF((select status from chicken where [PrimaryKey]='10118-78843')!='paid')
update [eComm]..[chicken] set [Status]='Overdue' where [PrimaryKey]='10118-78843' 
IF @@ROWCOUNT=0 insert into [eComm]..[chicken]([PrimaryKey],[Status]) values('10118-78843','Paid');

创建示例table代码：

create table chicken(
PrimaryKey nvarchar(50) not null,
Status nvarchar(10),
PRIMARY KEY (PrimaryKey)
)

目标（这是无效语法）：

IF((select status from chicken where [PrimaryKey]='10118-78843')!='paid')
{
update [eComm]..[chicken] set [Status]='Overdue' where [PrimaryKey]='10118-78843' 
IF @@ROWCOUNT=0 insert into [eComm]..[chicken]([PrimaryKey],[Status]) values('10118-78843','Paid');
}

否则，什么都不做

Answer 1

问题是您没有考虑如果存在现有行但状态为 paid。

会发生什么

您需要稍微调整一下逻辑：

declare @status varchar(20) = (
    select c.status
    from chicken c
    where c.[PrimaryKey] = '10118-78843'
);

if (@status != 'paid')
    update [chicken]
    set [Status] = 'Overdue'
    where [PrimaryKey] = '10118-78843';
else if (@status is null)
    insert into [chicken] ([PrimaryKey], [Status])
    values ('10118-78843', 'Paid');

或者：

insert into [chicken] ([PrimaryKey], [Status])
select '10118-78843', 'Paid'
where not exists (select 1
    from chicken c
    where c.[PrimaryKey] = '10118-78843'
);

if (@@ROWCOUNT = 0)
    update [chicken]
    set [Status] = 'Overdue'
    where [PrimaryKey] = '10118-78843'
      and status != 'Paid';

如果有条件，则 upsert else 什么都不做

if condition, then upsert else do nothing

sql

sql-server

sql-server-2012