zoukankan      html  css  js  c++  java
  • SQL基础语法(五)

    SQL INSERT INTO 语句
    INSERT INTO 语句 

    INSERT INTO 语句用于向表格中插入新的行。

    语法:INSERT INTO 表名称 VALUES (1, 2,....)

    我们也可以指定所要插入数据的列:

    INSERT INTO table_name (1, 2,...) VALUES (1, 2,....)
    插入新的行"Persons" 表:

    LastName
    FirstName
    Address
    City
    Carter
    Thomas
    Changan Street
    Beijing

    SQL 语句:INSERT INTO Persons VALUES ('Gates', 'Bill', 'Xuanwumen 10', 'Beijing')
    结果

    LastName
    FirstName
    Address
    City
    Carter
    Thomas
    Changan Street
    Beijing
    Gates
    Bill
    Xuanwumen 10
    Beijing

    在指定的列中插入数据"Persons" 表:

    LastName
    FirstName
    Address
    City
    Carter
    Thomas
    Changan Street
    Beijing
    Gates
    Bill
    Xuanwumen 10
    Beijing

    SQL 语句:INSERT INTO Persons (LastName, Address) VALUES ('Wilson', 'Champs-Elysees')
    结果

    LastName
    FirstName
    Address
    City
    Carter
    Thomas
    Changan Street
    Beijing
    Gates
    Bill
    Xuanwumen 10
    Beijing
    Wilson
     
    Champs-Elysees
     





    SQL UPDATE 语句Update 语句

    Update 语句用于修改表中的数据。

    语法:UPDATE 表名称 SET 列名称 = 新值 WHERE 列名称 = 某值
    Person:

    LastName
    FirstName
    Address
    City
    Gates
    Bill
    Xuanwumen 10
    Beijing
    Wilson
     
    Champs-Elysees
     

    更新某一行中的一个列

    我们为 lastname 是 "Wilson" 的人添加 firstname:

    UPDATE Person SET FirstName = 'Fred' WHERE LastName = 'Wilson' 
    结果

    LastName
    FirstName
    Address
    City
    Gates
    Bill
    Xuanwumen 10
    Beijing
    Wilson
    Fred
    Champs-Elysees
     

    更新某一行中的若干列

    我们会修改地址(address),并添加城市名称(city):

    UPDATE Person SET Address = 'Zhongshan 23', City = 'Nanjing'WHERE LastName = 'Wilson'
    结果

    LastName
    FirstName
    Address
    City
    Gates
    Bill
    Xuanwumen 10
    Beijing
    Wilson
    Fred
    Zhongshan 23
    Nanjing




    SQL DELETE 语句

    DELETE 语句

    DELETE 语句用于删除表中的行。

    语法:DELETE FROM 表名称 WHERE 列名称 = 
    Person:

    LastName
    FirstName
    Address
    City
    Gates
    Bill
    Xuanwumen 10
    Beijing
    Wilson
    Fred
    Zhongshan 23
    Nanjing

    删除某行

    "Fred Wilson" 会被删除:

    DELETE FROM Person WHERE LastName = 'Wilson' 
    结果:

    LastName
    FirstName
    Address
    City
    Gates
    Bill
    Xuanwumen 10
    Beijing

    删除所有行

    可以在不删除表的情况下删除所有的行。这意味着表的结构、属性和索引都是完整的:

    DELETE FROM table_name

    或者:

    DELETE * FROM table_name

  • 相关阅读:
    CH4302 Interval GCD
    20201017 模拟赛总结
    LOJ#2610. 「NOIP2013」货车运输
    POJ3696 The Luckiest number
    20200925 小练习总结
    更新一波状态
    AFO
    【扩展lucas定理】
    【LCT维护子树信息】uoj207 共价大爷游长沙
    [bzoj4589]Hard Nim(FWT快速沃尔什变化+快速幂)
  • 原文地址:https://www.cnblogs.com/kevin-kw/p/6109697.html
Copyright © 2011-2022 走看看