<span> 1</span> <span>DROP</span> <span>TABLE</span> <span>IF</span> <span>EXISTS</span><span> `nuvue`; </span><span> 2</span> <span> 3</span> <span>CREATE</span> <span>TABLE</span><span> `nuvue`( </span><span> 4</span> `id` <span>INT</span>(<span>10</span>) UNSIGNED <span>NOT</span> <span>NULL</span><span> AUTO_INCREMENT, </span><span> 5</span> `status` <span>TINYINT</span>(<span>2</span>) UNSIGNED <span>NOT</span> <span>NULL</span> <span>DEFAULT</span> <span>0</span> COMMENT <span>'</span><span>状态</span><span>'</span><span>, </span><span> 6</span> `uid` <span>INT</span>(<span>10</span>) UNSIGNED <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>创建用户</span><span>'</span><span>, </span><span> 7</span> `province_id` <span>TINYINT</span>(<span>3</span>) UNSIGNED <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>一级城市</span><span>'</span><span>, </span><span> 8</span> `city_id` <span>TINYINT</span>(<span>3</span>) UNSIGNED <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>二级地区</span><span>'</span><span>, </span><span> 9</span> `name` <span>VARCHAR</span>(<span>100</span>) <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>场地名称</span><span>'</span><span>, </span><span>10</span> `logo_url` <span>VARCHAR</span>(<span>100</span>) <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>场地Logo</span><span>'</span><span>, </span><span>11</span> `location_address` <span>VARCHAR</span>(<span>200</span>) <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>场地地址</span><span>'</span><span>, </span><span>12</span> `location_point` <span>VARCHAR</span>(<span>30</span>) <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>场地坐标</span><span>'</span><span>, </span><span>13</span> `caoncat_phone` <span>VARCHAR</span>(<span>20</span>) <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>联系人电话</span><span>'</span><span>, </span><span>14</span> `type` ENUM(<span>'</span><span>livehouse</span><span>'</span>,<span>'</span><span>theare</span><span>'</span>,<span>'</span><span>bar</span><span>'</span>,<span>'</span><span>bookshop</span><span>'</span>,<span>'</span><span>other</span><span>'</span>) <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>场地类型</span><span>'</span><span>, </span><span>15</span> `phone` <span>VARCHAR</span>(<span>20</span>) <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>场地电话</span><span>'</span><span>, </span><span>16</span> `area` <span>VARCHAR</span>(<span>10</span>) <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>场地面积</span><span>'</span><span>, </span><span>17</span> `people` <span>VARCHAR</span>(<span>10</span>) <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>容纳人数</span><span>'</span><span>, </span><span>18</span> `device` <span>VARCHAR</span>(<span>100</span>) <span>NOT</span> <span>NULL</span> <span>DEFAULT</span> <span>''</span> COMMENT <span>'</span><span>场地设备</span><span>'</span><span>, </span><span>19</span> `introduction` <span>VARCHAR</span>(<span>100</span>) <span>NOT</span> <span>NULL</span> <span>DEFAULT</span> <span>''</span> COMMENT <span>'</span><span>场地简介</span><span>'</span><span>, </span><span>20</span> `create_at` <span>DATETIME</span> <span>NOT</span> <span>NULL</span> COMMENT <span>'</span><span>创建时间</span><span>'</span><span>, </span><span>21</span> <span>PRIMARY</span> <span>KEY</span><span> `id`(`id`), </span><span>22</span> <span>UNIQUE</span> <span>KEY</span><span> `name`(`name`), </span><span>23</span> <span>KEY</span><span> `idx_type`(`type`), </span><span>24</span> <span>KEY</span><span> `idx_uid`(`uid`), </span><span>25</span> <span>KEY</span><span> `idx_status`(`status`), </span><span>26</span> <span>KEY</span><span> `idx_location`(`province_id`,`city_id`) </span><span>27</span> )ENGINE<span>=</span> Myisam <span>DEFAULT</span> CHARSET <span>=</span> utf8;
The above introduces a Mysql table creation statement, including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.

comment是备注、注释的意思。在MySQL数据库中,字段或列的注释是用属性comment来添加;创建新表的脚本中,可在字段定义脚本中添加comment属性来添加注释。想要查看已有表的所有字段的注释,可以使用“showfullcolumnsfrom表名”命令。在mysql中,COMMENT是备注、注释的意思。MySQL添加注释(comment)在MySQL数据库中,字段或列的注释是用属性comment来添加。创建新表的脚本中,可在字段定义脚本中添加comment属性来添加注释。示例代码如下:c

c语言中null和NULL的区别是:null是C语言中的一个宏定义,通常用来表示一个空指针,可以用于初始化指针变量,或者在条件语句中判断指针是否为空;NULL是C语言中的一个预定义常量,通常用来表示一个空值,用于表示一个空的指针、空的指针数组或者空的结构体指针。

在JavaScript 中,undefined和null都代表着“无”的概念:1、undefined 表示一个未初始化的变量或一个不存在的属性,当声明了一个变量但没有对其赋值时,这个变量的值就是undefined,访问对象中不存在的属性时,返回的值也是undefined;2、null表示一个空的对象引用,在某些情况下,可以将对象的引用设置为null,以便释放其占用的内存。

null和undefined都表示缺少值或未定义的状态,根据使用场景的不同,选择使用null还是undefined有以下一些指导原则:1、当需要明确指示一个变量为空或无效时,可以使用null;2、当一个变量已经声明但尚未赋值时,会被默认设置为undefined;3、当需要检查一个变量是否为空或未定义时,使用严格相等运算符“===”来判断变量是否为null或undefined。

null和undefined的区别在:1、语义含义;2、使用场景;3、与其它值的比较;4、与全局变量的关系;5、与函数参数的关系;6、可空性检查;7、性能考虑;8、在JSON序列化中的表现;9、与类型的关系。详细介绍:1、语义含义,null通常表示知道这个变量不会拥有任何有效的对象值,而undefined则通常表示变量未被赋值,或者对象没有此属性;2、使用场景等等。

在mysql使用过程中,日期一般都是以datetime、timestamp等格式进行存储的,但有时会因为特殊的需求或历史原因,日期的存储格式是varchar,那么我们该如何处理这个varchar格式的日期数据呢?使用函数:STR_TO_DATE(str,format)STR_TO_DATE(str,format)函数是DATE_FORMAT()函数的反函数。它需要一个字符串str和一个格式字符串格式。STR_TO_DATE()返回一个DATETIME值,如果格式字符串包含日期和时间部分,或如果字

用法:1、将引用类型的变量初始化为null,表示该变量当前不指向任何对象;2、将引用类型的变量设置为null,可以释放该变量所引用的对象的内存空间,帮助垃圾回收器回收该对象;3、使用null来检查一个引用是否为空,可以通过判断引用是否为null来避免NullPointerException异常的发生;4、在条件判断中使用null,可以判断某个引用是否为空。

mysql中char和varchar的区别有:1、CHAR是固定长度的,而VARCHAR是可变长度的;2、CHAR存储和检索效率高,而VARCHAR存储和检索效率不高;3、CHAR占用存储空间,而VARCHAR可以节省存储空间。


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