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HomeDatabaseMysql TutorialMySQL的增删改查以及常用的一些操作

增加记录 INSERT INTO 表名(字段名,字段名) VALUES (值,值);删除记录 DELETE FROM 表名 WHERE 条件(oracal中就可以不要from

增加记录
  INSERT INTO 表名(字段名,字段名) VALUES (值,值);
删除记录
  DELETE FROM 表名 WHERE 条件(oracal中就可以不要from)
修改记录
  UPDATE 表名 SET 字段=值,字段=值 WHERE 条件
查询记录
  SELECT 字段,字段 FROM 表名 WHERE 条件

了解了一些最基本的操作命令后,我们再来学习如何创建一个数据库和数据库表。


    1、使用SHOW语句找出在服务器上当前存在什么数据库:


mysql> SHOW DATABASES;
+----------+
| Database |
+----------+
| mysql |
| test |
+----------+
3 rows in set (0.00 sec)


    2、创建一个数据库abccs
    mysql> CREATE DATABASE abccs;
    注意不同操作系统对大小写的敏感。


    3、选择你所创建的数据库
    mysql> USE abccs
    Database changed
    此时你已经进入你刚才所建立的数据库abccs. 

    4、 创建一个数据库表

    首先看现在你的数据库中存在什么表:
    mysql> SHOW TABLES;
    Empty set (0.00 sec)
    说明刚才建立的数据库中还没有数据库表。下面来创建一个数据库表mytable:
    我们要建立一个你公司员工的生日表,表的内容包含员工姓名、性别、出生日期、出生城市。

mysql> CREATE TABLE mytable (name VARCHAR(20), sex CHAR(1),
 birth DATE, birthaddr VARCHAR(20)) ENGINE=InnoDB DEFAULT CHARSET=gb2312;
Query OK, 0 rows affected (0.00 sec)
 

    由于name、birthadd的列值是变化的,因此选择VARCHAR,其长度不一定是20。可以选择从1到255的任何长度,如果以后需要改变它的字长,可以使用ALTER TABLE语句。);性别只需一个字符就可以表示:"m"或"f",因此选用CHAR(1);birth列则使用DATE数据类型。

    创建了一个表后,我们可以看看刚才做的结果,用SHOW TABLES显示数据库中有哪些表:

mysql> SHOW TABLES;
+---------------------+
| Tables in menagerie |
+---------------------+
| mytables |
+---------------------+
 

    5、显示表的结构:


mysql> DESCRIBE mytable;
+-------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------+-------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| sex | char(1) | YES | | NULL | |
| birth | date | YES | | NULL | |
| deathaddr | varchar(20) | YES | | NULL | |
+-------------+-------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
 

    6、 往表中加入记录


    我们先用SELECT命令来查看表中的数据:字段带别名查询的时候,中文的别名要加上单引号;
    mysql> select * from mytable;
    Empty set (0.00 sec)
    这说明刚才创建的表还没有记录。


    加入一条新记录:


mysql> insert into mytable
-> value (′abccs′,′f′,′1977-07-07′,′china′);
Query OK, 1 row affected (0.05 sec)
 

 


    再用上面的SELECT命令看看发生了什么变化。我们可以按此方法一条一条地将所有员工的记录加入到表中。


    7、用文本方式将数据装入一个数据库表


    如果一条一条地输入,很麻烦。我们可以用文本文件的方式将所有记录加入你的数据库表中。创建一个文本文件“mysql.txt”,每行包含一个记录,用定位符(tab)把值分开,,并且以在CREATE TABLE语句中列出的列次序给出,例如:


abccs f 1977-07-07 china  
mary f 1978-12-12 usa
tom m 1970-09-02 usa


    使用下面命令将文本文件“mytable.txt”装载到mytable表中:mysql> LOAD DATA LOCAL INFILE "mytable.txt(加路径)" INTO TABLE pet(表名);


    再使用如下命令看看是否已将数据输入到数据库表中:mysql> select * from mytable;

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