Question

This is a fairly basic question, I currently have two tables and in the second table there is a foreign key column for table A.

Table A:

id       Name
----------------
1        Name1
2        Name2

Table B:

id       Name      Parent
-------------------------
1        John      1

What happens:

• My PHP script inserts Name1 into Table A and mysql inserts the id.
• My PHP script needs to insert John into Table B AND set Parent to be the id of the query that was just inserted.

Answer 1

After the first insert, you can do:

$res = mysql_query('SELECT LAST_INSERT_ID()');
$row = mysql_fetch_array($res);
$lastInsertId = $row[0];

Alternatively, you can use mysql_insert_id. However, from the manual:

mysql_insert_id() will convert the
return type of the native MySQL C API
function mysql_insert_id() to a type
of long (named int in PHP). If your
AUTO_INCREMENT column has a column
type of BIGINT (64 bits) the
conversion may result in an incorrect
value. Instead, use the internal MySQL
SQL function LAST_INSERT_ID() in an
SQL query.

Because of this, the first method I listed is preferred if your column uses — or may use in the future — BIGINT.