软件测试常⽤SQL查询语句（⼀）⼀、简单查询
from > distinct > select > order by > limit
(1) 普通查询：select name,age from students;
(2) 起别名查询：select s.name,s.age from students as s;
(3) 分页查询：select name,age from students limit 0，10;
(4)排序查询：select name,age,id from students order by age desc,id asc;
(5)去重查询：select distinct age from students;
⼆、条件查询
from > where > distinct > select > distinct > order by > limit
eg: select name,age, from students where name=‘xiaoming’ and age=18;
三、⾼级查询（聚合函数）
sum求和 | avg平均数 | max最⼤数 | 最⼩数min
group by | 分组查询
(1) 求班级男⼥平均年龄分别为多少？
select sex avg(age) from students group by sex;
count(*)记录含空值记录数 | count(列名）不含空记录数
(2) 求班级男⼥分别为多少⼈？
select sex count(*) from students group by sex;
(3) 查询每个部门⾥，每种职位的平均底薪。
select deptno,job,count(*),avg(sal) from t_emp group by deptno,job order by deptno;
group_concat | 可以搭配group by使⽤，使某个字段连接成字符串
常用的sql查询语句有哪些
(4) 查询每个部门内底薪超过2000元的⼈数和员⼯姓名。
select deptno grouo_concat(ename) count(*) from t_emp where sal>=2000 group by deptno;
having | 跟在group by 后⾯的条件语句
eg: select sex avg(age) from students group by sex having age in(10,20);

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