学习mysql之后的一点总结(基础)_MySQL
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2024-02-12 09:15:22
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1.想要在命令提示符下操作mysql服务器,添加系统变量。(计算机-系统属性――环境变量――path)
2.查询数据表中的数据;
select selection_list select * /columns
from table_list from table1/table2
where primary_constraint
group by grouping_columns
order by sorting_colomns desc降序 select * from table order by id desc;
having second_constraint
limit count select * from table where id limit 1,4;
2 常用的统计函数:avg(字段),sum(字段),count(字段),min(字段),
select sum(字段2) as 别名 ,字段1 from table group by 字段1;
3 算数运算,字符串,以及逻辑运算构造表达式:select * (price*0.8) as '80%' from table;打八折bitsCN.com
2.查询数据表中的数据;
select selection_list select * /columns
from table_list from table1/table2
where primary_constraint
group by grouping_columns
order by sorting_colomns desc降序 select * from table order by id desc;
having second_constraint
limit count select * from table where id limit 1,4;
2 常用的统计函数:avg(字段),sum(字段),count(字段),min(字段),
select sum(字段2) as 别名 ,字段1 from table group by 字段1;
3 算数运算,字符串,以及逻辑运算构造表达式:select * (price*0.8) as '80%' from table;打八折bitsCN.com
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