picking up a single record from merge table, if it has duplicate entries

Hi,

 

Currently we have multiple MYISAM tables, we create merge table out of
these multiple tables to retrieve data.

Now we have same record available in multiple tables, data retrieved
from merge table produces duplicate records.

But what we need is to get only one record out of these multiple records
based on some condition.

 

For e.g.

Table1 has

Rec1

Rec2

Rec3

 

Table2 has

Rec4

Rec5

Rec1

 

Now the data retrieved from merge table produces

Rec1

Rec2

Rec3

Rec4

Rec5

Rec1

 

But we need one instance of record Rec1. The selection of this record is
based on the query, some times it is based on the max bandwidth
(bandwidth is a field), some time based on distinct.

 

Is there a SQL query, which will resolve my requirement?

 

Thanks in advance.

 

Ila.