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PHP MySQL Functions to get the Field length from a result set |
mysql_field_ln function will return the length of field associated with the field. This command takes one result set as input along with a filed identifier or an offset. It returns a string holding filed length details. Here is the command.
string mysql_field_len(int result, int field_offset)
Please note that the function mysql_field_len is not returning the length of the data stored in the field. It is giving the length of the filed assigned in the structure of the table. So our data stored in that field can be less or equal the assigned length of that filed. Check the end of this tutorial on how to get length of the data stored in a row.
We will try to develop one script using our student table to display the field length of all the fields.
<?
$result = mysql_query ("SELECT * FROM student");
$no_of_fields = mysql_num_fields ($result);
$no_of_records = mysql_num_rows ($result);
$i = 0;
$table_name = mysql_field_table ($result, $i);
echo "Your '".$table_name."' table has ".$no_of_fields";
echo " fields and ".$no_of_records." records <BR>";
echo "The table has the following fields <BR>";
while ($i < $no_of_fields) {
// name of the field mysql_field_name
$name = mysql_field_name ($result, $i);
echo "Field name:<b>$name</b><br>";
// Field length field mysql_field_len
$len = mysql_field_len ($result, $i);
echo "Field Length: $len<br>";
$i++;
}
?>
The above code will display the field type with the fields of the student table.
The result of the above script is here
Your ’student’ table has 4 fields and 52 records
The table has the following fields
Field name:id
Field Length: 2
Field name:name
Field Length: 50
Field name:class
Field Length: 10
Field name:mark
Field Length: 12
As you have seen in the above code the length of the field is given but not the length of the data stored in the filed. To get the length of data stored in a field we have to use mysql_fetch_lengths function.
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