摘要：字符串函数ASCII返回字符串首字母的ascii编码select ASCII('name')select ASCII(name) from xueshengselect *from xuesheng where ASCII(name)>=200CHAR--将ascii代码转换成对应的字符select... 阅读全文

摘要：规范函数：绝对值select abs(-5)print abs(-5)表中取绝对值的方法：select code,name,abs(chinese)as yuwen from xueshengselect *from xuesheng where ABS(chinese)>90天花板、地板selec... 阅读全文

摘要：分组group byselect class from xuesheng group by classselect class,AVG(chinese)from xuesheng group by classselect math from xuesheng where math >80 group... 阅读全文

摘要：聚合函数--求平均select AVG(age) as 年龄 from xueshengselect AVG(chinese) as 语文 from xuesheng where class = 1*只能对数字类型的进行操作--求个数select COUNT(*) from xuesheng/*查询... 阅读全文

摘要：分离、附加、备份、还原--去重select distinct 列名from表名--更新update fenshu set name = ‘李四’where code = 9--更改表名sp_rename 表名drop database 数据库名（删除数据库）drop table 表名Delete f... 阅读全文