查看“各种连接（等值连接、内连接、外连接、左连接、右连接、全连接）”的源代码

=== 演示数据 ===

==== 学生表和学生数据 ====
<syntaxhighlight lang="sql">
CREATE TABLE `student` (
  `sid` int(11) NOT NULL AUTO_INCREMENT,
  `snum` int(11) NOT NULL,
  `sname` varchar(20) NOT NULL,
  `sage` tinyint(4) DEFAULT NULL,
  `sclass` smallint(6) NOT NULL,
  PRIMARY KEY (`snum`),
  UNIQUE KEY `student_num` (`sid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `sql`.`student`
(`snum`,
`sname`,
`sage`,
`sclass`)
VALUES
(20201101,'张三',20,150),
(20201102,'李四',18,151),
(20201103,'王五',19,151),
(20201104,'赵六',18,150),
(20201105,'钱七',21,151),
(20201106,'孙八',20,152);

</syntaxhighlight>

==== 课程表和课程数据 ====
<syntaxhighlight lang="sql">
create table course(
cid int not null auto_increment,
cnum int not null primary key,
cname varchar(20) not null,
unique key course_num (cid)
) engine = innodb auto_increment = 1 default charset = utf8;

INSERT INTO `sql`.`course`
(`cnum`,
`cname`)
VALUES
(101, '数据结构'),
(102, '编译原理'),
(103, '计算机网络'),
(105, '计算机组成原理'),
(106, '数据库');
</syntaxhighlight>

==== 学生课程关系表 ====
<syntaxhighlight lang="sql">
CREATE TABLE `sc` (
  `scid` int(11) NOT NULL AUTO_INCREMENT,
  `snum` int(11) NOT NULL,
  `cnum` int(11) NOT NULL,
  `grade` smallint(6) DEFAULT NULL,
  PRIMARY KEY (`snum`,`cnum`),
  UNIQUE KEY `scid` (`scid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

</syntaxhighlight>



=== 等值连接/显式内连接 ===

=== 自然连接 ===

=== 外连接 ===

=== 内连接 ===

=== 全连接 ===

=== 左/右外连接 ===