Implementation code for moving the pointer to the initial position of the data set in PHP [mysql_data_seek]

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Implementation code for moving the pointer to the initial position of the data set in PHP [mysql_data_seek]_PHP tutorial

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Jul 21, 2016 pm 03:15 PM

data mysql php s Seek code Location copy accomplish pointer data of move

Copy code The code is as follows:

// 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); //The key is here
while ($row = mysql_fetch_assoc($result)) {
// do other stuff with $row
}
? >

Definition and Usage

The mysql_data_seek() function moves the pointer of the internal result.

Syntax

mysql_data_seek(data,row) Parameter Description
data Required. Returns a result set of type resource. This result set is obtained from a call to mysql_query().
row required. The number of rows in the new result set pointer you want to set. 0 indicates the first record.

Description

mysql_data_seek() moves the row pointer inside the MySQL result specified by the data parameter to the specified row number.
Then calling mysql_fetch_row() will return that row.
row starts from 0. The value range of row should be from 0 to mysql_num_rows - 1.
But if the result set is empty (mysql_num_rows() == 0), moving the pointer to 0 will fail with an E_WARNING level error and mysql_data_seek() will return false.

Return value

Returns true if successful, false if failed.

Tips and Notes

Note: mysql_data_seek() can only be used with mysql_query(), not mysql_unbuffered_query().

Example

Copy code The code is as follows:

 
$con = mysql_connect ("localhost", "hello", "321"); 
if (!$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); 
?> 

Output:

Copy code The code is as follows:

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

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

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