将这两个 SQL 语句合并为一个

Question

我有两个 tables t1, t2 列 name, invoice, total.

我正在使用此查询获取 T2 中而非 T1 中的行

select * 
from t2  
where name = (select source from info) 
except 
(select * from t1)

它工作正常并返回几行，我想要的是在一条语句中删除这些返回的行。

我试过了，但它删除了 T2 中的所有行，而不仅仅是查询返回的行。

delete from t2 
where exists ((select * 
               from t2  
               where name = (select source from info) 
               except 
               (select * from t1) 
             ))

这是我的数据示例：

T1

T2

返回的数据（存在于 T2 而不是 T1 中名称为 C2 的地方）

第 3 个 table 信息是获取名称，在本例中是 C2。

提前致谢。

Answer 1

I am using this query to get the rows that in T2 and not in T1

我要使用的查询是：

select t2.*
from t2
where not exists (select 1 from t1 where t1.? = t2.name);

不清楚t1中匹配列的名称是什么。

这很容易变成 delete:

delete from t2
where not exists (select 1 from t1 where t1.? = t2.name);

Answer 2

您可以通过 t2 到 t1 的左连接来实现：

delete t
from (
  select * from t2
  where name = (select source from info)
) t left join t1
on t1.name = t.name and t1.invoice = t.invoice and t1.total = t.total
where t1.name is null

参见demo。

如果你想使用 NOT EXISTS:

delete t
from (
  select * from t2
  where name = (select source from info)
) t 
where not exists (
  select 1 from t1
  where name = t.name and invoice = t.invoice and total = t.total
)

参见demo。

结果（t2 中剩余的行）：

> name | invoice | total
> :--- | ------: | ----:
> C1   |       1 |   150
> C1   |       2 |   300
> C2   |       1 |   200
> C2   |       2 |   165

Answer 3

您想从 t2 中删除有两个条件：

姓名=（select来源信息）
行在 t1 中没有匹配项

声明：

delete from t2
where name = (select source from info)
and not exists
(
  select *
  from t1
  where t1.name = t2.name
    and t1.invoice = t2.invoice
    and t1.total = t2.total
);

或更短的 IN 子句，仅在允许 IN 和元组的 DBMS 中可用：

delete from t2
where name = (select source from info)
and (name, invoice, total) not in (select name, invoice, total from t1);

将这两个 SQL 语句合并为一个

Combine these two SQL statements into one

sql

sql-server

sql-delete

sql-except