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q_id | q_title | ss_s_id | ss_q_id | score | ts |
---|---|---|---|---|---|
1 | Quiz 1 | 40204123 | 1 | 80 | 2021-01-12 15:37:11 |
2 | Quiz 2 | 40204123 | 2 | 75 | 2021-01-12 15:38:06 |
3 | Quiz 3 | 40204123 | 3 | 30 | 2021-01-13 22:13:13 |
q_id | q_title |
---|---|
1 | Quiz 1 |
2 | Quiz 2 |
3 | Quiz 3 |
4 | Quiz 4 |
s_id | s_name |
---|---|
40204123 | Student2_name |
q_id | q_title | s_id | s_name |
---|---|---|---|
1 | Quiz 1 | 40204123 | Student2_name |
2 | Quiz 2 | 40204123 | Student2_name |
3 | Quiz 3 | 40204123 | Student2_name |
4 | Quiz 4 | 40204123 | Student2_name |
q_id | q_title | s_id | s_name |
---|---|---|---|
4 | Quiz 4 | 12345678 | Student1_name |
3 | Quiz 3 | 12345678 | Student1_name |
2 | Quiz 2 | 12345678 | Student1_name |
1 | Quiz 1 | 12345678 | Student1_name |
4 | Quiz 4 | 40204123 | Student2_name |
3 | Quiz 3 | 40204123 | Student2_name |
2 | Quiz 2 | 40204123 | Student2_name |
1 | Quiz 1 | 40204123 | Student2_name |
4 | Quiz 4 | 40213894 | Student3_name |
3 | Quiz 3 | 40213894 | Student3_name |
2 | Quiz 2 | 40213894 | Student3_name |
1 | Quiz 1 | 40213894 | Student3_name |
4 | Quiz 4 | 98765432 | Student4_name |
3 | Quiz 3 | 98765432 | Student4_name |
2 | Quiz 2 | 98765432 | Student4_name |
1 | Quiz 1 | 98765432 | Student4_name |
q_id | q_title | s_id | s_name | score |
---|---|---|---|---|
1 | Quiz 1 | 12345678 | Student1_name | 80 |
2 | Quiz 2 | 12345678 | Student1_name | 25 |
3 | Quiz 3 | 12345678 | Student1_name | 90 |
4 | Quiz 4 | 12345678 | Student1_name | 90 |
1 | Quiz 1 | 40204123 | Student2_name | 80 |
2 | Quiz 2 | 40204123 | Student2_name | 75 |
3 | Quiz 3 | 40204123 | Student2_name | 30 |
4 | Quiz 4 | 40204123 | Student2_name | 0 |
1 | Quiz 1 | 40213894 | Student3_name | 90 |
2 | Quiz 2 | 40213894 | Student3_name | 95 |
3 | Quiz 3 | 40213894 | Student3_name | 0 |
4 | Quiz 4 | 40213894 | Student3_name | 100 |
1 | Quiz 1 | 98765432 | Student4_name | 0 |
2 | Quiz 2 | 98765432 | Student4_name | 0 |
3 | Quiz 3 | 98765432 | Student4_name | 0 |
4 | Quiz 4 | 98765432 | Student4_name | 0 |
EXPLAIN |
---|
-> Nested loop left join (cost=2.05 rows=4) (actual time=0.018..0.031 rows=4 loops=1) -> Table scan on q (cost=0.65 rows=4) (actual time=0.011..0.015 rows=4 loops=1) -> Single-row index lookup on ss using PRIMARY (ss_s_id=40204123, ss_q_id=q.q_id) (cost=0.28 rows=1) (actual time=0.003..0.003 rows=1 loops=4) |
EXPLAIN |
---|
-> Nested loop left join (cost=2.05 rows=4) (actual time=0.016..0.127 rows=4 loops=1) -> Index scan on q using PRIMARY (cost=0.65 rows=4) (actual time=0.010..0.110 rows=4 loops=1) -> Single-row index lookup on ss using PRIMARY (ss_s_id=40204123, ss_q_id=q.q_id) (cost=0.28 rows=1) (actual time=0.003..0.003 rows=1 loops=4) |