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To select only data that matches a specified criteria, add a WHERE clause to the SELECT statement.
在SELECT语句中加入一条WHERE子句可以选择仅与指定的要求相匹配的数据。
To select only data that matches a specific criteria, add a WHERE clause to the SELECT statement.
在SELECT语句中加入一条WHERE子句可以选择仅与指定的要求相匹配的数据。
SELECT column FROM table WHERE column operator value |
The following operators can be used with the WHERE clause:
下面介绍WHERE子句中的操作符:
Operator 操作符 | Description 描述 |
= | Equal 等于 |
!= | Not equal 不等于 |
> | Greater than 大于 |
< | Less than 小于 |
>= | Greater than or equal 大于等于 |
<= | Less than or equal 小于等于 |
BETWEEN | Between an inclusive range 指定查找的范围 |
LIKE | Search for a pattern 查找样式 |
Note: SQL statements are not case sensitive. WHERE is the same as where.
注意:SQL语句是“字母大小写不敏感”的语句(它不区分字母的大小写),即:“WHERE”和“where”是一样的。
To get PHP to execute the statement above we must use the mysql_query() function. This function is used to send a query or command to a MySQL connection.
在PHP内创建数据库,我们需要在mysql_query()函数内使用上述语句。这个函数是用来发送MySQL数据库连接建立的请求和指令的。
The following example will select all rows from the "Person" table, where FirstName='Peter':
下面的例子:从“Person”表中选取FirstName=’Peter’的所有记录:
<?php $con = mysql_connect("localhost","peter","abc123"); if (!$con) { die('Could not connect: ' . mysql_error()); } mysql_select_db("my_db", $con); $result = mysql_query("SELECT * FROM person WHERE FirstName='Peter'"); while($row = mysql_fetch_array($result)) { echo $row['FirstName'] . " " . $row['LastName']; echo "<br />"; } ?> |
The output of the code above will be:
上述代码将输出下面的结果:
Peter Griffin |