Creating distinct pairs of values from database table

SELECT * FROM tbl1;
A
B

SELECT t1.val, t2.val
FROM tbl1 t1, tbl1 t2;

A A
B A
A B
B B

SELECT t1.val, t2.val
FROM tbl1 t1, tbl1 t2
WHERE t1.val <> t2.val;

B A
A B

SELECT t1.val, t2.val
FROM tbl1 t1, tbl1 t2
WHERE t1.val <> t2.val
AND t1.val < t2.val;

A B