0	1
0	1
0	2
0	2
0	3
0	3
0	3
1	2
2	1
0	3
3	0
3	0
2	0
1	1
1	1
0	1
0	1
0	2
0	2
0	3
0	3
0	3
1	2
2	1
0	3
3	0
3	0
2	0
1	1
1	1
SELECT * FROM t1, t2
1	1	1	1
1	1	1	\N
2	2	1	1
2	2	1	\N
3	3	1	1
3	3	1	\N
4	4	1	1
4	4	1	\N
SELECT * FROM t1, t2 WHERE t1.a = t2.a
1	1	1	1
1	1	1	\N
SELECT t1.a, t2.a FROM t1, t2 WHERE t1.b = t2.b
1	1
SELECT t1.a, t2.b, t3.b FROM t1, t2, t3 WHERE t1.a = t2.a AND t1.a = t3.a
1	1	1
1	1	\N
1	\N	1
1	\N	\N
SELECT t1.a, t2.b, t3.b FROM t1, t2, t3 WHERE t1.b = t2.b AND t1.b = t3.b
1	1	1
SELECT t1.a, t2.b, t3.b, t4.b FROM t1, t2, t3, t4 WHERE t1.a = t2.a AND t1.a = t3.a AND t1.a = t4.a
1	1	1	1
1	1	1	\N
1	1	\N	1
1	1	\N	\N
1	\N	1	1
1	\N	1	\N
1	\N	\N	1
1	\N	\N	\N
SELECT t1.a, t2.b, t3.b, t4.b FROM t1, t2, t3, t4 WHERE t1.b = t2.b AND t1.b = t3.b AND t1.b = t4.b
1	1	1	1
SELECT t1.a, t2.b, t3.b, t4.b FROM t1, t2, t3, t4 WHERE t1.a = t2.a AND t2.a = t3.a AND t3.a = t4.a
1	1	1	1
1	1	1	\N
1	1	\N	1
1	1	\N	\N
1	\N	1	1
1	\N	1	\N
1	\N	\N	1
1	\N	\N	\N