2026.11.3mysql上课

查询学生基本信息

select * from stu;
select student_name,sno from stu;
select student_name as 姓名,2026-sage 出生年份,sdept as'系 别' from stu;
select distinct sno from sc;
select sno,grade
from sc
where grade >=90;
select sno,grade
from sc
where grade !=90;
select sno,grade
from sc
where grade >=70 and grade <90;
select sno,grade
from sc
where grade not between 70 and 90;
select *
from stu
where sdept='软件系'or sdept='计算机系'
select *
from stu
where sdept('软件系','计算机系');
select *
from stu
where student_name like '张%'#包括多个
select *
from stu
where student_name like'小%';
select *
from course
where cname like '%#%' escape '#';#转译字符
select sno, student_name
from sc
where grade is null;#成绩为空不能用=，用is