查询一张表:

    1. select * from 表名;

    查询指定字段:

    select 字段1,字段2,字段3….from 表名;
    

    where条件查询:

    select 字段1,字段2,字段3 frome 表名 where 条件表达式;
    例:select * from t_studect where id=1;
        select * from t_student where age>22;
    

    in关键字查询:

    select 字段1,字段2 frome 表名 where 字段 [not]in(元素1,元素2);
    例:select * from t_student where age in ('21','23');
        select * from t_student where age not in ('21','23');
    

    between and的范围查询:

    select 字段1,字段2 frome 表名 where 字段 [not]between 取值1 and 取值2;
    例:select * from t_student where age between 21 and 29;
        select * from t_student where age not between 21 and 29;
    

    like的模糊查询:

    select 字段1,字段2… frome 表名 where 字段 [not] like ‘字符串’;
    “%”代表任意字符;
    “_”代表单个字符;
    例:select * from t_student where stuName like ‘张三”;
        select * from t_student where stuName like ‘张三%”;
        select * from t_student where stuName like ‘%张三%”;//含有张三的任意字符
        select * from t_student where stuName like ‘张三_”
    

    空值查询:

    select 字段1,字段2… from 表名 where 字段  is[not] null;
    

    and多条件查询:

    select 字段1,字段2…from 表名 where 条件表达式1 and 条件表达式2 [and 条件表达式n]
    例:select * frome t_student where gradeName=’一年级’ and age=23
    

    or的多条件查询:

    select 字段1,字段2…from 表名 where 条件表达式1 or 条件表达式2 [or 条件表达式n]
    例:select * frome t_student where gradeName=’一年级’ or age=23;//或者,条件只要满足一个
    

    distinct去重复查询:

    select distinct 字段名 from 表名;
    

    对查询结果排序order by

    select 字段1,字段2…from 表名 order by 属性名 [asc|desc]
    例:select * from t_student order by age desc;//降序,从大到小
        select * from t_student order by age asc;//升序,asc默认可以不写
    

    内联表查询inner join

    select 
    字段1,字段2,字段3...
    from 
    表1  inner join 表2 on 表1.字段 = 表2.字段 
    例:select 
    order_id,buyer_name,purchase_date,inland_name,inland_info,logistics_channel_code,freeze_amount,deduct_amount
    from 
    by_mws_order  inner join by_order_logistics on by_mws_order.id = by_order_logistics.oid
    

    查询最近七点的数据

    SELECT * FROM 表名 where DATE_SUB(CURDATE(), INTERVAL 7 DAY) <= date(时间字段名)
    

    查询用户授权权限

    SHOW GRANTS FOR developers;
    

    授予用户权限

    GRANT lock tables ON 库名.* TO '用户'@'%';
    

    删除用户权限

    REVOKE 权限 ON *.* FROM '用户'@'%';