七種SQL JOINS 1.SELECT select_list FROM TABLEA A LEFT JOIN TABLEB B ON A.Key=B.Key 2.SELECT select_list FROM TABLEA A RIGHT JOIN TABLEB B ON A.Key=B.Key ...
七種SQL JOINS
1.SELECT select_list FROM TABLEA A LEFT JOIN TABLEB B ON A.Key=B.Key
2.SELECT select_list FROM TABLEA A RIGHT JOIN TABLEB B ON A.Key=B.Key
3.SELECT select_list FROM TABLEA A LEFT JOIN TABLEB B ON A.Key=B.Key
WHERE B.key is NULL4.SELECT select_list FROM TABLEA A RIGHT JOIN TABLEB B ON A.Key=B.key
WHERE A.Key is null5.SELECT select_list FROM TABLE A INNER JOIN TABLEB B ON A.Key=B.Key
6.SELECT select_list FROM TABLE A FULL OUTER JOIN TABLEB B ON A.Key=B.Key(Oracle支持)
7.SELECT select_list FROM TABLE A FULL OUTER JOIN TABLEB B ON
WHERE A.Key IS NULL OR B.Key IS NULL(Oracle支持)
運行效果
create table tbl_dept(
id int(11) not null auto_increment,
deptName varchar(30) default null,
locAdd varchar(40) default null,
primary key(id)
)engine=innodb auto_increment=1 default charset=utf8;
create table tbl_emp(
id int(11) not null auto_increment,
name varchar(20) default null,
deptId int(11) default null,
primary key(id),
key fk_dept_id (deptId)
#constraint fk_dept_id foreign key (deptId) references tbl_dept (id)
)engine=innodb auto_increment=1 default charset=utf8;
insert into tbl_dept(deptName,locAdd)values('RD',11);
insert into tbl_dept(deptName,locAdd)values('HR',12);
insert into tbl_dept(deptName,locAdd)values('MK',13);
insert into tbl_dept(deptName,locAdd)values('MIS',14);
insert into tbl_dept(deptName,locAdd)values('FD',16);
insert into tbl_emp(name,deptId)values('z2',1);
insert into tbl_emp(name,deptId)values('z3',1);
insert into tbl_emp(name,deptId)values('z4',1);
insert into tbl_emp(name,deptId)values('z4',1);
insert into tbl_emp(name,deptId)values('z6',1);
insert into tbl_emp(name,deptId)values('w5',2);
insert into tbl_emp(name,deptId)values('s7',3);
insert into tbl_emp(name,deptId)values('s8',4);
insert into tbl_emp(name,deptId)values('s9',51)
select * from tbl_emp;
select * from tbl_emp;
兩個集合笛卡尓積 select * from tbl_emp,tbl_dept;
select * from tbl_emp a inner join tbl_dept b on a.deptId=b.id;
select * from tbl_emp a left join tbl_dept b on a.deptId=b.id;
select * from tbl_emp a right join tbl_dept b on a.deptId=b.id;
select * from tbl_emp a left join tbl_dept b on a.deptId=b.id where b.id is null;
select * from tbl_emp a right join tbl_dept b on a.deptId=b.id where a.deptId is null;
select * from tbl_emp a left join tbl_dept b on a.deptId=b.id
union
select * from tbl_emp a right join tbl_dept b on a.deptId=b.id;
select * from tbl_emp a left join tbl_dept b on a.deptId=b.id where b.id is null
union
select * from tbl_emp a right join tbl_dept b on a.deptId=b.id where a.deptId is null;
