-- 内连接查询 SELECT id,name,age,dept_name FROM tb_students_info INNER JOIN tb_departments WHERE tb_students_info.dept_id=tb_departments.dept_id; -- 左外连接查询 SELECT name,dept_name FROM tb_students_info s LEFT OUTER JOIN tb_departments d ON s.dept_id = d.dept_id; -- 右外连接查询 SELECT name,dept_name FROM tb_students_info s RIGHT OUTER JOIN tb_departments d ON s.dept_id = d.dept_id; -- 自连接查询 SELECT s1.id, s1.name FROM tb_students_info s1,tb_students_info s2 WHERE s1.dept_id=s2.dept_id AND s2.id = 1; -- IN子查询 SELECT name FROM tb_students_info WHERE dept_id IN (SELECT dept_id FROM tb_departments WHERE dept_type= 'A' ); -- 内层子查询 SELECT dept_id FROM tb_departments WHERE dept_type='A'; -- 外层子查询 SELECT name FROM tb_students_info WHERE dept_id IN(1,2); -- NOT IN子查询 SELECT name FROM tb_students_info WHERE dept_id NOT IN (SELECT dept_id FROM tb_departments WHERE dept_type='A'); -- 带等号运算符的子查询 SELECT name FROM tb_students_info WHERE dept_id = (SELECT dept_id FROM tb_departments WHERE dept_name='Computer'); -- 带不等号运算符的子查询 SELECT name FROM tb_students_info WHERE dept_id <> (SELECT dept_id FROM tb_departments WHERE dept_name='Computer'); -- EXISTS子查询 SELECT * FROM tb_students_info WHERE EXISTS (SELECT dept_name FROM tb_departments WHERE dept_id=1); -- 分组查询与计数函数的应用 SELECT dept_id,COUNT(*) AS total FROM tb_students_info GROUP BY dept_id; -- 分组查询 SELECT dept_id,GROUP_CONCAT(name) AS names FROM tb_students_info GROUP BY dept_id; -- 使用HAVING关键字设置条件 SELECT dept_id,GROUP_CONCAT(name) AS names FROM tb_students_info GROUP BY dept_id HAVING COUNT(name)>1; -- 查询以特定字符开头的记录 SELECT * FROM tb_departments WHERE dept_name REGEXP '^C'; -- 查询以特定字符串开头的记录 SELECT * FROM tb_departments WHERE dept_name REGEXP '^Ch'; -- 查询以特定字符结尾的记录 SELECT * FROM tb_departments WHERE dept_name REGEXP 'y$'; -- 查询以特定字符串结尾的记录 SELECT * FROM tb_departments WHERE dept_name REGEXP 'my$'; -- 用符号“.”匹配任意一个字符 SELECT * FROM tb_departments WHERE dept_name REGEXP 'o.y'; -- 用符号“*”匹配多个字符 SELECT * FROM tb_departments WHERE dept_name REGEXP '^Ch*'; -- 用符号“+”匹配多个字符 SELECT * FROM tb_departments WHERE dept_name REGEXP '^Ch+'; -- 匹配指定单个字符串 SELECT * FROM tb_departments WHERE dept_name REGEXP 'in'; -- 匹配指定多个字符串 SELECT * FROM tb_departments WHERE dept_name REGEXP 'in|on'; -- 匹配任意一个字母 SELECT * FROM tb_departments WHERE dept_name REGEXP '[io]'; -- 匹配任意一个数字 SELECT * FROM tb_departments WHERE dept_call REGEXP '[123]'; -- 匹配指定字符以外的字符 SELECT * FROM tb_departments WHERE dept_name REGEXP '[^a-t]';