如何用一条语句把一张表的数据插入到另一张数据库表中

两个数据库名分别为：data1 和 data2，对应的表依次分别为：table1和table2。我想把data1里的table1的数据插入到data2里的table2，怎么写SQL语句？
情况一：data2表中无table2表

select
* into
data2.dbo.table2in
data2 from
data1.dbo.table1

情况二：结构不一样或者你要指定字段

insert into data2.table2(字段1,字段2,字段) select 字段j,字段k,字段m fromdata1.table1

情况三：结构一样

insert into data2.table2select * from data1.table1

insert into tableb..bb(b1,b2,b3) select a1,a2,a3 from tablea..aa

insert into 数据库1.a(id,name...)select id,name...from 数据库2.b

insert into tableb(b1,b2,b3) select a1,a2,a3 from[wjjj].[dbo].[fbase]

insert into tableb(b1,b2,b3) select a1,a2,a3 from[数据库2名].[dbo].[表]

实例

create database Testa

use Testa

create table Tablea

(

id int primary key identity(1,1) not null,

userName varchar(50) not null,

pwd varchar(50) not null,

age int not null

)

create database TestB

use TestB

create table Tableb

(

id int primary key identity(1,1) not null,

ageb int not null,

pass varchar(50) not null

)

insert into Tableb(ageb,pass) select age,pwd from Testa.dbo.Tablea

insert into Tablea(age,pwd) select ageb,pass from TestB.dbo.Tableb