Mssqlsql efficiently associates with the update batch update of subqueries

Source: Internet
Author: User
Mssqlsql efficiently associates with the update batch update of subqueries

Mssql SQL efficiently associates with the update batch update of subqueries

Mssql SQL efficiently associates with the update batch update of subqueries
/*
Update with associated subqueries
-- 1. Create a test table

Create TABLE Table1
(
A varchar (10 ),
B varchar (10 ),
C varchar (10 ),
CONSTRAINT [PK_Table1] PRIMARY KEY CLUSTERED
(
A ASC
)
) ON [PRIMARY]

Create TABLE Table2
(
A varchar (10 ),
C varchar (10 ),
CONSTRAINT [PK_Table2] PRIMARY KEY CLUSTERED
(
A ASC
)
) ON [PRIMARY]
GO
-- 2. Create Test Data
Insert into Table1 values ('zhao ', 'asds', null)
Insert into Table1 values ('money', 'asds ', '123 ')
Insert into Table1 values ('sun', 'asds ', '80 ')
Insert into Table1 values ('lil', 'asds ', null)

Insert into Table2 values ('zhao ', '90 ')
Insert into Table2 values ('money', '123 ')
Insert into Table2 values ('sun', '80 ')
Insert into Table2 values ('lil', '95 ')
GO
Select * from Table1

-- 3. Update through Update
Update Table1 set c = (select c from Table2 where a = Table1.a) where c is null
GO

-- 4. display the updated result
Select * from Table1
GO
-- 5. Delete the test table
Drop TABLE Table1
Drop TABLE Table2

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.