Finding unmatched records between two tables

Suppose there are two tables - A and B and they have a couple of common key fields.  I  want to select those records from A which do not have a matching record in B. What will be most efficient way to do that?
Thank you.


Look at this link .......... i think this may help you a bit to achieve ur requirement
Comparing Internal Tables: -
Internal tables can be compared with the operands that are used to compare other data objects. The most important criteria for comparing the internal table are the number of lines they contain. The larger the number of lines, the larger it is for comparisons. If the both the internal tables have same number of lines, then they are compared line by line. The operands used for comparisons are LE, LT, GE, GT, EQ, NE.
Except for EQ, the comparison stops at the first pair of components that identifies the condition false.