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 field identifier or an offset. It returns a string holding field length details. Here is the command.

string mysql_field_len(int result, int field_offset)

Deprecated Removed in PHP 7 , Use these alternatives
MYSQLI
PDO

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 field assigned in the structure of the table. So our data stored in that field can be less or equal the assigned length of that field. 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.

MySQL Field
Field Details of table Field Length Data Length of field Field Names of table Field Type in a table Field Flag associated field

<?Php
$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 field. To get the length of data stored in a field we have to use mysql_fetch_lengths function.

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