SELECT INTO FROM和 INSERT INTO SELECT

[size=small;]SELECT INTO 和 INSERT INTO SELECT 两种表复制语句? [/size]


Insert是T-sql中常用语句，Insert INTO table(field1,field2,...) values(value1,value2,...)这种形式的在应用程序开发中必不可少。但我们在开发、测试过程中，经常会遇到需要表复制的情况，如将一个table1的数据的部分字段复制到table2中，或者将整个table1复制到table2中，这时候我们就要使用SELECT INTO 和 INSERT INTO SELECT 表复制语句了。

????? 1.INSERT INTO SELECT语句

????? 语句形式为：Insert into Table2(field1,field2,...) select value1,value2,... from Table1

????? 要求目标表Table2必须存在，由于目标表Table2已经存在，所以我们除了插入源表Table1的字段外，还可以插入常量。示例如下：

**INSERT INTO SELECT语句复制表数据?
--1.创建测试表
????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),
????????d?int,
????????CONSTRAINT?[PK_Table2]?PRIMARY?KEY?CLUSTERED
????????(
????????????a?ASC
????????)
????)?ON?[PRIMARY]
????GO
????--2.创建测试数据
????Insert?into?Table1?values('赵','asds','90')
????Insert?into?Table1?values('钱','asds','100')
????Insert?into?Table1?values('孙','asds','80')
????Insert?into?Table1?values('李','asds',null)
????GO
????select?*?from?Table2

????--3.INSERT?INTO?SELECT语句复制表数据
????Insert?into?Table2(a,?c,?d)?select?a,c,5?from?Table1
????GO

????--4.显示更新后的结果
????select?*?from?Table2
????GO
????--5.删除测试表
????drop?TABLE?Table1
????drop?TABLE?Table2
????? 2.SELECT INTO FROM语句

????? 语句形式为：SELECT vale1, value2 into Table2 from Table1

????? 要求目标表Table2不存在，因为在插入时会自动创建表Table2，并将Table1中指定字段数据复制到Table2中。示例如下：

**SELECT INTO FROM创建表并复制表数据?
??--1.创建测试表
????create?TABLE?Table1
????(
????????a?varchar(10),
????????b?varchar(10),
????????c?varchar(10),
????????CONSTRAINT?[PK_Table1]?PRIMARY?KEY?CLUSTERED
????????(
????????????a?ASC
????????)
????)?ON?[PRIMARY]
????GO

????--2.创建测试数据
????Insert?into?Table1?values('赵','asds','90')
????Insert?into?Table1?values('钱','asds','100')
????Insert?into?Table1?values('孙','asds','80')
????Insert?into?Table1?values('李','asds',null)
????GO

????--3.SELECT?INTO?FROM语句创建表Table2并复制数据
????select?a,c?INTO?Table2?from?Table1
????GO

????--4.显示更新后的结果
????select?*?from?Table2
????GO
????--5.删除测试表
????drop?TABLE?Table1
????drop?TABLE?Table2?