join the two tables which possess one to many relationship In drupal,the content type table and my own table is used to do some operations. Im having two tables namely Table1:'content_field_mem_id' &amp;
                             Table2:'Ex'
description of my content_field_mem_id is

+--------------------+------------------+------+-----+---------+-------+
| Field              | Type             | Null | Key | Default | Extra |
+--------------------+------------------+------+-----+---------+-------+
| vid                | int(10) unsigned | NO   | PRI | 0       |       |
| nid                | int(10) unsigned | NO   | MUL | 0       |       |
| field_mem_id_value | int(11)          | YES  |     | NULL    |       |
| sid                | int(30)          | YES  | MUL | NULL    |       |
+--------------------+------------------+------+-----+---------+-------+
4 rows in set (0.00 sec)


The member Id values are inside the field_mem_id_value field. 
Another Table Ex description is shown below : 

mysql&gt; desc Ex;
+---------------+-------------+------+-----+---------+----------------+
| Field         | Type        | Null | Key | Default | Extra          |
+---------------+-------------+------+-----+---------+----------------+
| sid           | int(30)     | NO   | PRI | NULL    | auto_increment |
| mem_id        | varchar(30) | YES  |     | NULL    |                |
| nature_of_due | tinytext    | YES  |     | NULL    |                |
| amount        | int(30)     | YES  |     | NULL    |                |
| date          | date        | YES  |     | NULL    |                |
| paidby        | tinytext    | YES  |     | NULL    |                |
+---------------+-------------+------+-----+---------+----------------+
6 rows in set (0.00 sec)


The above table Ex doesnt contain any values.i.e)the Ex table has 0 rows. After posting operation by the admin Ex table will gets affected.

My aim is to show the view to the user using the Ex table. 

The content_field_mem_id table consists 1000 numbers of member id which was imported by me and inserted into that content_field_mem_id table.

The relationship between this two table is one to many relationship i.e) Each member can pay any of the fees . But member fees is must so one member can have many transactions on the second table. 

How to join the both tables and how to set the foreign key constraints?. I have set the foreign constraint for the mem_id ,it throws me an error not an syntax error.

I want to join the tables and the second table has to be taken for the view purpose and second table member id can be duplicated cos of many transactions.
The relationship appears to be between content_field_mem_id.field_mem_id_value and ex.mem_id
However, since content_field_mem_id.field_mem_id_value is an int and ex.mem_id is a varchar, you will need to cast/convert one of the columns as part of your join.  

It would be more reliable (although slower) to convert the int column to a varchar.

You didn't say which DB technology you are using, so I can't show the exact syntax for the convert (it is very different between MS SQL/Oracle/DB2/etc).