php中将指针移动到数据集初始位置的实现代码[mysql_data

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php中将指针移动到数据集初始位置的实现代码[mysql_data_seek]

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Jun 13, 2016 am 11:57 AM

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复制代码代码如下:

// Start snipit 1
$sql = "SELECT * from

";
$result = mysql_query($sql);
while ($row = mysql_fetch_assoc($result)) {
// do stuff with $row
}
mysql_data_seek($result, 0); //关键是这儿
while ($row = mysql_fetch_assoc($result)) {
// do other stuff with $row
}
?>

定义和用法

mysql_data_seek() 函数移动内部结果的指针。

语法

mysql_data_seek(data,row)参数描述
data 必需。返回类型为 resource 的结果集。该结果集从 mysql_query() 的调用中得到。
row 必需。想要设定的新的结果集指针的行数。0 指示第一个记录。

说明

mysql_data_seek() 将 data 参数指定的 MySQL 结果内部的行指针移动到指定的行号。
接着调用 mysql_fetch_row() 将返回那一行。
row 从 0 开始。row 的取值范围应该从 0 到 mysql_num_rows - 1。
但是如果结果集为空（mysql_num_rows() == 0），要将指针移动到 0 会失败并发出 E_WARNING 级的错误，mysql_data_seek() 将返回 false。

返回值

如果成功则返回 true，失败则返回 false。

提示和注释

注释：mysql_data_seek() 只能和 mysql_query() 一起使用，而不能用于 mysql_unbuffered_query()。

例子

复制代码代码如下:

$con = mysql_connect("localhost", "hello", "321");
if (!$con)
{
die('Could not connect: ' . mysql_error());
}
$db_selected = mysql_select_db("test_db",$con);
$sql = "SELECT * from Person";
$result = mysql_query($sql,$con);
print_r(mysql_fetch_row($result));
mysql_data_seek($result,3);
print_r(mysql_fetch_row($result));
mysql_close($con);
?>

输出：

复制代码代码如下:

Array
(
[0] => Adams
[1] => John
[2] => London
)

Array
(
[0] => Carter
[1] => Thomas
[2] => Beijing
)

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