把一个表的数据插入到另一个表:INSERT INTO SELECT / SELECT INTO

经常会看到这样的问题:

怎样把一个表的数据插入到另外一张表?

怎么有条件的把一个表的数据插入到另外一张表中?

不使用游标怎么把一个表的数据插入到另外一张表?

有两种方法可以是实现,而且不使用游标.下面两种方法性能远好于游标.

1.INSERT INTO SELECT

这种方法常用在目标表已经存在数据库中.需要从源表把数据插入到目标表的情况.如果目标表和源表的列相同,就不必列出数据列了.

USE AdventureWorks

GO

----Create TestTable

CREATE TABLE TestTable (FirstName VARCHAR(100), LastName VARCHAR(100))

----INSERT INTO TestTable using SELECT

INSERT INTO TestTable (FirstName, LastName)

SELECT FirstName, LastName

FROM Person.Contact

WHERE EmailPromotion = 2

----Verify that Data in TestTable

SELECT FirstName, LastName

FROM TestTable

----Clean Up Database

DROP TABLE TestTable

GO

USE AdventureWorks

GO

----Create TestTable

CREATE TABLE TestTable (FirstName VARCHAR(100), LastName VARCHAR(100))

----INSERT INTO TestTable using SELECT

INSERT INTO TestTable --(FirstName, LastName)

SELECT FirstName, LastName

FROM Person.Contact

WHERE EmailPromotion = 2

----Verify that Data in TestTable

SELECT FirstName, LastName

FROM TestTable

----Clean Up Database

DROP TABLE TestTable

GO

仔细看看有什么区别.

2.SELECT INTO

这种方法用在目标表事先不存在于数据库.在插入数据的同时新建表.新表的字段名和数据类型和需要插入的列相同.

USE AdventureWorks

GO

----Create new table and insert into table using SELECT INSERT

SELECT FirstName, LastName

INTO TestTable

FROM Person.Contact

WHERE EmailPromotion = 2

----Verify that Data in TestTable

SELECT FirstName, LastName

FROM TestTable

----Clean Up Database

DROP TABLE TestTable

GO

我也常用它来复制数据结构,但不插入数据.

USE AdventureWorks

GO

----Create new table and insert into table using SELECT INSERT

SELECT FirstName, LastName

INTO TestTable

FROM Person.Contact

WHERE 1=2

DROP TABLE TestTable

GO