帮忙做道题，Sql语句的，谢啦~~

Question

有两个表Table_A和Table_B，字段和内容分别是表 Table_A
userid    username     Address
------------------------------------
1         A
2         B
3         C
表 Table_B
userid   username      Address
----------------------------
1                     D
2                     E
3                     F
问题一：请写出一条SQL语句，目的是将Table_B和Table_A比较，如果userid相同，就把Table_B中Address的值写到Table_A的字段Address里。问题二：请写出一条SQL语句，目的是将Table_B和Table_A比较，如果userid相同，就把Table_A中的username的值、Table_B中的Address的值读出来。 

Answer 1

update b
set b.address = a.address
from table_a a ,table_b b
where a.userid = b.usridselect  a.username,b.address
from table_a a
join table_b b
on a.userid = b.userid

Answer 2

update   b 
set   b.address   =   a.address 
from   table_a   a  left join table_b   b on   a.userid   =   b.usrid 
select     a.username,b.address 
from   table_a   a left join   table_b   b on   a.userid   =   b.userid

Answer 3

樓上正解!不過      "   a.userid   =   b.usrid  "呵呵,筆誤!!!
應該"  a.userid   =   b.userid"

Answer 4

create table Table_A(
userid int,
username char(1),
Address char(1)
)insert into Table_A(userid,username) values(1,'A')
insert into Table_A(userid,username) values(2,'B')
insert into Table_A(userid,username) values(3,'C')create table Table_B(
userid int,
username char(1),
Address char(1)
)insert into Table_B(userid,Address) values(1,'D')
insert into Table_B(userid,Address) values(2,'E')
insert into Table_B(userid,Address) values(3,'F')
update a set a.Address = b.Address
from Table_A a join Table_B b
on a.userid=b.useridselect * from Table_Adrop table Table_A,Table_B/*
userid      username Address 
----------- -------- ------- 
1           A        D
2           B        E
3           C        F
（所影响的行数为 3 行）
*/

Answer 5

update a
set a.address=b.address
from Table_A a ,Table_B b 
where a.userid=b.useridselect *
from Table_Auserid      username Address
----------- -------- -------
1           A        D
2           B        E
3           C        F(3 行受影响)
select a.username,b.Address
from Table_A a,Table_B b
where a.userid=b.useridusername Address
-------- -------
A        D
B        E
C        F(3 行受影响)

Answer 6

update   b  set   b.address   =   a.address  from   Table_A   a   ,Table_B   b  where   a.userid   =   b.usrid 
select  a.username,b.address from   Table_A  a ,   Table_B   b where   a.userid   =   b.userid

Answer 7

update a set a.address=b.address from Table_A a, Table_B b where a.userid=b.useridselect a.username,b.address from Table_A a,Table_B b where a.userid=b.userid

Answer 8

update a
set address=b.address
from table_a a,table_b b
where a.userid=b.useridselect a.username,b.address
from table_a a,table_b b
where a.userid=b.userid