mysql创建和删除表

创建表 简单的方式 CREATE TABLE person (number INT( 11 ),name VARCHAR( 255 ),birthday DATE); 或者是 CREATE TABLE IF NOT EXISTS person (number INT( 11 ),name VARCHAR( 255 ),birthday DATE); 查看mysql创建表: SHOW CREATE table person; CREATE TA

创建表

简单的方式

<span>CREATE TABLE person (
number INT(</span><span>11</span><span>),
name VARCHAR(</span><span>255</span><span>),
birthday DATE
);</span>

或者是

<span>CREATE TABLE IF NOT EXISTS person (
number INT(</span><span>11</span><span>),
name VARCHAR(</span><span>255</span><span>),
birthday DATE
);</span>

查看mysql创建表:

<span>SHOW CREATE table person;

</span><span>CREATE TABLE `person` (
  `number` </span><span>int</span>(<span>11</span><span>) DEFAULT NULL,
  `name` varchar(</span><span>255</span><span>) DEFAULT NULL,
  `birthday` </span><span>date</span><span> DEFAULT NULL
) ENGINE</span>=MyISAM DEFAULT CHARSET=utf8;

查看表所有的列：

<span>SHOW FULL COLUMNS from person;
</span>+----------+--------------+-----------------+------+-----+---------+-------+---------------------------------+---------+
| Field    | Type         | Collation       | Null | Key | Default | Extra | Privileges                      | Comment |
+----------+--------------+-----------------+------+-----+---------+-------+---------------------------------+---------+
| number   | <span>int</span>(<span>11</span>)      | NULL            | YES  |     | NULL    |       | <span>select</span>,insert,update,references |         |
| name     | varchar(<span>255</span>) | utf8_general_ci | YES  |     | NULL    |       | <span>select</span>,insert,update,references |         |
| birthday | <span>date</span>         | NULL            | YES  |     | NULL    |       | <span>select</span>,insert,update,references |         |
+----------+--------------+-----------------+------+-----+---------+-------+---------------------------------+---------+

 

创建临时表

<span>CREATE TEMPORARY TABLE temp_person (
number INT(</span><span>11</span><span>),
name VARCHAR(</span><span>255</span><span>),
birthday DATE
);</span>

在创建表格时，您可以使用TEMPORARY关键词。只有在当前连接情况下，TEMPORARY表才是可见的。当连接关闭时，TEMPORARY表被自动取消。这意味着两个不同的连接可以使用相同的临时表名称，同时两个临时表不会互相冲突，也不与原有的同名的非临时表冲突。（原有的表被隐藏，直到临时表被取消时为止。）您必须拥有CREATE TEMPORARY TABLES权限，才能创建临时表。

 

如果表已存在，则使用关键词IF NOT EXISTS可以防止发生错误。

 

<span>CREATE TABLE IF NOT EXISTS person2 (
number INT(</span><span>11</span><span>),
name VARCHAR(</span><span>255</span><span>),
birthday DATE
);</span>

注意，原有表的结构与CREATE TABLE语句中表示的表的结构是否相同，这一点没有验证。注释：如果您在CREATE TABLE...SELECT语句中使用IF NOT EXISTS，则不论表是否已存在，由SELECT部分选择的记录都会被插入。

 

在CREATE TABLE语句的末尾添加一个SELECT语句，在一个表的基础上创建表

CREATE TABLE new_tbl SELECT * FROM orig_tbl;

注意，用SELECT语句创建的列附在表的右侧，而不是覆盖在表上

mysql> SELECT *<span> FROM foo;
</span>+---+
| n |
+---+
| <span>1</span> |
+---+<span>
mysql</span>><span> CREATE TABLE bar (m INT) SELECT n FROM foo;
mysql</span>> SELECT *<span> FROM bar;
</span>+------+---+
| m    | n |
+------+---+
| NULL | <span>1</span> |
+------+---+

也可以明确地为一个已生成的列指定类型

CREATE TABLE foo (a TINYINT NOT NULL) SELECT b+<span>1</span> AS a FROM bar;

根据其它表的定义（包括在原表中定义的所有的列属性和索引），使用LIKE创建一个空表:

CREATE TABLE new_tbl LIKE orig_tbl;

 创建一个有主键，唯一索引，普通索引的表:

<span>CREATE TABLE `people` (
  `peopleid` smallint(</span><span>6</span><span>) NOT NULL AUTO_INCREMENT,
  `firstname` </span><span>char</span>(<span>50</span><span>) NOT NULL,
  `lastname` </span><span>char</span>(<span>50</span><span>) NOT NULL,
  `age` smallint(</span><span>6</span><span>) NOT NULL,
  `townid` smallint(</span><span>6</span><span>) NOT NULL,
  PRIMARY KEY (`peopleid`),
  UNIQUE KEY `unique_fname_lname`(`firstname`,`lastname`),
  KEY `fname_lname_age` (`firstname`,`lastname`,`age`)
) ;</span>

其中peopleid是主键,以firstname和lastname两列建立了一个唯一索引,以firstname,lastname,age三列建立了一个普通索引

 

删除表

DROP TABLE  tbl_name;

或者是

DROP TABLE IF EXISTS tbl_name;