PHP重点3---表中简单查询、增删改

1、最简单查询
select * from car;
2、查询指定列
select name,oil,powers from car;
3、对查出的列名修改名字
select name as '车名',oil as '油量',powers as '动力' from car;
4、按条件查询
select name,oil,powers from car where oil = 8.7;
5、多条件查询
select name oil,powers from car where oil = 8.7 or powers = 160;

select name oil,powers from car where oil = 8.7 and powers = 160;
6、范围查询
select * from car where price>=40 and price<=60;

select * from car where price between 40 and 60;
7、离散查询
select * from car where powers = 130 or powers = 150 or powers = 170;

select * from car where powers in(130,150,170);

select * from car where powers not in(130,150,170);

8、模糊查询
select * from car where name like '%宝马%';                            %号是所有字符
select * from car where name like '_宝马'  ;                              _号是一个字符
9、排序查询             asc升序  desc降序   order对结果集进行排序
select * from car order by oil asc;

select * from car order by oil desc;

10、去重复查询 distinct
select distinct brand from car;
11、分页查询
select * from car limit 10,5;       第一个数字表示跳过的条数，第二个数字表示跳过后展示的条数。

n表示页数，m表示每页显示的条数

limit(n-1)*m,m;
12、聚合函数查询
count(列名) 总数的意思
sum(列名) 求和的意思
avg(列名) 平均的意思
max(列名) min(列名)

select count(*) from car;
select sum(price) from car;
select avg(price) from car;
select max(price) from car;
select min(price) from car;

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增删改

1、添加表中数据

insert into car values('','','','');

insert into car(字段1，值1) values(字段2，值2）;

insert into car set 字符1，值1 vables(字符2，值2）;

2、修改表数据

update car set 字段1 = 值 where 字段2（要看字段类型） = 值2

3、删除表数据

delete from 表名 where 字段1 = 值1