[BUG] Self join doesn't work properly

[Yury-Fridlyand]

Describe the bug
Self join doesn't work properly.

To Reproduce

opensearchsql> SELECT c1.`key`, c1.num1, c2.str0 FROM calcs AS c1, calcs AS c2;
fetched rows / total rows = 17/17
+----------+-----------+-----------+
| c1.key   | c1.num1   | c2.str0   |
|----------+-----------+-----------|
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
| null     | null      | null      |
+----------+-----------+-----------+
opensearchsql> SELECT c1.`key`, c1.num1, c1.str0 FROM calcs AS c1;
fetched rows / total rows = 17/17
+-------+--------+-----------------+
| key   | num1   | str0            |
|-------+--------+-----------------|
| key00 | 8.42   | FURNITURE       |
| key01 | 6.71   | FURNITURE       |
| key02 | 9.78   | OFFICE SUPPLIES |
| key03 | 7.43   | OFFICE SUPPLIES |
| key04 | 9.05   | OFFICE SUPPLIES |
| key05 | 9.38   | OFFICE SUPPLIES |
| key06 | 16.42  | OFFICE SUPPLIES |
| key07 | 11.38  | OFFICE SUPPLIES |
| key08 | 9.47   | TECHNOLOGY      |
| key09 | 12.4   | TECHNOLOGY      |
| key10 | 10.32  | TECHNOLOGY      |
| key11 | 2.47   | TECHNOLOGY      |
| key12 | 12.05  | TECHNOLOGY      |
| key13 | 10.37  | TECHNOLOGY      |
| key14 | 7.1    | TECHNOLOGY      |
| key15 | 16.81  | TECHNOLOGY      |
| key16 | 7.12   | TECHNOLOGY      |
+-------+--------+-----------------+

Expected behavior
First query should yield the same result as the second one.

[chloe-zh]

@Yury-Fridlyand Thanks for reporting this issue, currently our syntax does not support self join yet. Will investigate and plan it if the support is necessary. Thanks!