Table of Contents for

MySQL in a Nutshell, 2nd Edition

This function returns the length of each column within a particular row of a results set. The values returned can vary for each row fetched, depending on the data contained in the columns. Here is an example:

...
mysql_query(mysql, "SELECT * FROM clients");
result = mysql_store_result(mysql);
row = mysql_fetch_row(result);
unsigned int num_fields = mysql_num_fields(result);
unsigned long *lengths = mysql_fetch_lengths(result);
for(i = 0; i < num_fields; i++)
   {
    field = mysql_fetch_field(result);
    printf("%s %lu \n", field->name, lengths[i]);
   }
...

This example retrieves one row of the results and checks the lengths of the fields in that row. To retrieve each field, the SELECT statement would need to be altered and a while statement would be wrapped around the for statement to loop through each row.