zoukankan      html  css  js  c++  java
  • mysql常用sql语法

    一、创建主键的三种方式

    1、

    CREATE TABLE user(
       uid INT PRIMARY KEY,
       uname VARCHAR(10),
       address VARCHAR(20)
    )

    2、

    CREATE TABLE user(
       uid INT,
       uname VARCHAR(10),
       address VARCHAR(20),
       PRIMARY KEY(uid)
    )

    3、

    CREATE TABLE user(
     uid INT,
     uname VARCHAR(10),
     address VARCHAR(20)
    )
    ALTER TABLE user ADD PRIMARY KEY(uid);

    4、联合主键

    CREATE TABLE user(
        uid INT,
        uname VARCHAR(10),
        address VARCHAR(20),
        PRIMARY KEY(uid,uname)
    )

    5、删除主键

    ALTER TABLE USER DROP PRIMARY KEY;

  • 相关阅读:
    term "JavaScript"
    Pro Git
    Pro Git
    Pro Git
    git
    flask
    OJ
    [蓝桥杯]Huffuman树
    priority_queue优先队列
    [蓝桥杯]高精度加法
  • 原文地址:https://www.cnblogs.com/zhangshuaivole/p/12792144.html
Copyright © 2011-2022 走看看