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      SQL語句快速入門

       靜幻堂 2018-08-26
      中國統(tǒng)計(jì)網(wǎng) 2017-05-26 18:25:10

      SQL語句快速入門

      下面就為大家?guī)硪黄猄QL語句快速入門 。個人覺得挺不錯的,學(xué)習(xí)MYSQL數(shù)據(jù)庫還是有點(diǎn)幫助的,給大家做個參考吧。

      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;

      ||連接符使用以及 加減乘除以及括號的使用

      SQL> select employee_id,first_name||'.'||last_name,salary*(1+0.1)/100,manager_id

      2 from employees;

      +-做正負(fù)號使用

      SQL> select -salary from employees;

      <>,>,<,=,!=等比較操作符

      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(比任意一個都)

      select * from employees where employee_id >any(100,101,102);

      some 是 SQL-92 標(biāo)準(zhǔn)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;

      邏輯操作符

      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啞元表沒有表需要查詢的時候可以用它

      select sysdate from dual;

      select 1*2*3*4*5 from dual;

      以上這篇SQL語句快速入門 就是分享給大家的全部內(nèi)容了,希望能啟發(fā)大家的思路,如有更多意見,歡迎下方評論~

      End.

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