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mysql数据库语言学习

news 来源：原创 2025/4/30 18:11:56

为了应对工作需要，结合《SQL必知必会》书籍、菜鸟教程、deepseek、csdn等整理自己的学习过程，不是一次性更新完，本博客中知识点仅供参考。

一、基本查询语句

# 选择数据库
use lepao;/* 一、选择列 */
# 1）选择单列
select `城市名称` from siteinfo;
# 2）选择多列
select `城市名称`,`城市ID` from siteinfo;
# 3）选择所有列
select * from siteinfo;
# 4）返回唯一值
select distinct `城市名称` from siteinfo;/* 二、选择行 */
# 选择前5行
select * from menkan order by `日期` limit 5;
# 选择后5行
select * from menkan order by `日期` desc limit 5;
# 选择随机5行
select * from menkan order by rand() limit 5;/* 三、排序 */
# 1）单列升序
select `站点名称` from siteinfo order by `站点ID`;
# 2）多列排序
select `站点名称` from siteinfo order by `城市ID`,`站点ID`;
# 3）指定排序方向
select `站点名称` from siteinfo order by `城市ID`,`站点ID`;/* 四、筛选 */
# 1）等于
select * from menkan where `是否达成`=1;
# 2）范围
select * from menkan where `注册盈余` between 5 and 10;
# 3）空值
select * from menkan where `未达标` is null;
# 4）多条件
select * from menkan where `日期`='2025-04-01' and `总达标`>100;
select * from menkan where `日期`='2025-04-01' or `日期`='2025-04-02';
select * from menkan where (`日期`='2025-04-01' or `日期`='2025-04-02') and `总达标`>150;
# 5）匹配
select * from menkan where `日期` in ('2025-04-01','2025-04-02');
# 6）不匹配
select * from menkan where not `日期` in ('2025-04-01','2025-04-02');/* 五、通配符 */
# 1）多个字符
select * from menkan where `主站点名称` like '江苏%';
# 2）单个字符
select * from workstatus where `骑手名称` like '王_';
# 3）字符集
select * from workstatus where `骑手名称` regexp '[王张]';
select * from workstatus where `骑手名称` not regexp '[王张]';