SQL练习13：从titles表获取按照title进行分组
题目描述考察知识点解题思路题目描述
从titles表获取按照title进行分组，每组个数大于等于2，给出title以及对应的数目t。
CREATE TABLE IF NOT EXISTS `titles` (`emp_no` int(11) NOT NULL,`title` varchar(50) NOT NULL,`from_date` date NOT NULL,`to_date` date DEFAULT NULL);INSERT INTO titles VALUES(10001,'Senior Engineer','1986-06-26','9999-01-01');INSERT INTO titles VALUES(10002,'Staff','1996-08-03','9999-01-01');INSERT INTO titles VALUES(10003,'Senior Engineer','1995-12-03','9999-01-01');INSERT INTO titles VALUES(10004,'Engineer','1986-12-01','1995-12-01');INSERT INTO titles VALUES(10004,'Senior Engineer','1995-12-01','9999-01-01');INSERT INTO titles VALUES(10005,'Senior Staff','1996-09-12','9999-01-01');INSERT INTO titles VALUES(10005,'Staff','1989-09-12','1996-09-12');INSERT INTO titles VALUES(10006,'Senior Engineer','1990-08-05','9999-01-01');INSERT INTO titles VALUES(10007,'Senior Staff','1996-02-11','9999-01-01');INSERT INTO titles VALUES(10007,'Staff','1989-02-10','1996-02-11');INSERT INTO titles VALUES(10008,'Assistant Engineer','1998-03-11','2000-07-31');INSERT INTO titles VALUES(10009,'Assistant Engineer','1985-02-18','1990-02-18');INSERT INTO titles VALUES(10009,'Engineer','1990-02-18','1995-02-18');INSERT INTO titles VALUES(10009,'Senior Engineer','1995-02-18','9999-01-01');INSERT INTO titles VALUES(10010,'Engineer','1996-11-24','9999-01-01');INSERT INTO titles VALUES(10010,'Engineer','1996-11-24','9999-01-01');
考察知识点
COUNT，GROUP BY。
解题思路
用COUNT()函数和GROUP BY语句可以统计同一title值的记录条数t，再选择t大于2的数据即可。
SELECT title, count(emp_no) AS tFROM titlesGROUP BY titleHAVING t >= 2
题目来源：牛客网-SQL数据库实战题
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