MySQL命令範例

windows上啓動MySQL服務：net start mysql

windows上停止MySQL服務：net stop mysql

連接MySQL服務器命令：mysql -u root -p 123456 -h 127.0.0.1

#修改定界符
delimiter //
#設置客戶端字符集
set names gbk
#使用某一個特定的數據庫
use test;
#顯示所有的數據庫
show databases;
#創建數據庫
create database db1;
#顯示創建的數據庫
show create database db1;
#修改數據庫
alter database db1 character set utf8;
#刪除數據庫
drop database db1;
#創建數據表
create table tb_name(
id int unsigned primary key auto_increment,
username varchar(32) not null
);
#修改數據表
#修改列定義
#ALTER TABLE tbl_name MODIFY [COLUMN] col_name column_definition  [FIRST | AFTER col_name]
alter table tb1 modify age int unsigned not null default 0;
#修改列名稱
#ALTER TABLE tbl_name CHANGE [COLUMN] old_col_name new_col_name column_definition [FIRST | AFTER col_name]
alter talbe tb_name change id new_id int unsigned;
#刪除數據表
drop table tb1;
#數據表更名
#方法一
#ALTER TABLE tbl_name RENAME [TO | AS] new_tbl_name
#方法二
#RENAME TABLE tbl_name TO new_tbl_name [, tbl_name2 TO new_tbl_name2] ...

#對查詢結果進行排序
#[ORDER BY {col_name | expr | position} [ASC | DESC]], ...]
select * from users order by age;
select * from users order by age desc;
select * from users order by age, id desc;

/*自定義函數
CREATE FUNCTION function_name
RETURNS {STRING | INTEGER | REAL | DECIMAL}
routine_body
*/
create function f1() returns varchar(30)
return date_format(now(), '%Y年%m月%d日 %H點:%i分:%s秒');

create function f2(num1 smallint unsigned, num2 smallint unsigned)
returns float(10, 2) unsigned
return (num1 + num2) / 2;

create function adduser(username varchar(20))
returns int unsigned 
begin
insert test(username) values(username);
return last_insert_id();
end

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
DECLARE M INT;
SET M = N - 1;
  RETURN (
      # Write your MySQL query statement below.
      SELECT DISTINCT Salary FROM Employee ORDER BY Salary DESC LIMIT M, 1
  );
END

#定義用戶變量
set @var = 100;
select @var

#定義局部變量
#DECLARE var_name[,...] type [DEFAULT value]

#限制查詢結果返回的數量
#[LIMIT {[offset,] row_count OFFSET offset}]