PHP学习之SQL语句快速入门

Select * from tablename 
SQL> select * from employees; 
Select select list from tablename 
SQL> select employee_id,first_name from employees; 
Select distinct … from tablename 
SQL> select distinct manager_id from employees; 
||连接符使用以及 加减乘除以及括号的使用 
SQL> select employee_id,first_name||'.'||last_name,salary*(1+0.1)/100,manager_id 
2 from employees; 
+-做正负号使用 
SQL> select -salary from employees; 
<>,>,<,=,!=等比较操作符 
SQL> select * from employees where salary >13000; 
SQL> select * from employees where salary <13000; 
SQL> select * from employees where salary <>13000; 
SQL> select * from employees where salary =13000; 
In 
SQL> select -salary from employees where employee_id in (100,101,102); 
SQL> select -salary from employees where employee_id in (select employee_id from employees); 
not in 
SQL> select -salary from employees where employee_id not in (100,101,102); 
Any(比任意一个都) 
select * from employees where employee_id >any(100,101,102); 
some 是 SQL-92 标准的 any 的等效物 
select * from employees where employee_id >any(100,101,102); 
all（比所有的都） 
select * from employees where employee_id >all(100,101,102); 
between and 
select * from employees where employee_id between 100 and 102; 
not between and 
select * from employees where employee_id not between 100 and 102; 
逻辑操作符 
And 和 or 
select * from employees where employee_id > 100 and employee_id < 1000; 
select * from employees where employee_id > 100 or employee_id < 1000; 
Order by 
Desc 
select * from employees where employee_id between 100 and 102 order by employee_id desc; 
Asc 
select * from employees where employee_id between 100 and 102 order by employee_id asc; 
dual哑元表没有表需要查询的时候可以用它 
select sysdate from dual; 
select 1*2*3*4*5 from dual;