Primary key SE11

Hi everyone,

i created a table with 2 columns( character(1));

i like to have first column unique and also the second column.

First column should accept only the unique entries ,Even the second column

A A

B B

<b>A</b> C . this combination should not be allowed. because A is repeated in column 1.

C <b>B </b>. this shouldnt be allowed as column 2 needs column 2 unique.

Ur help is appreciated