1. INNER, LEFT, RIGHT and CROSS Result Count

What is result when we are joining these two table (INNER, LEFT, RIGHT and CROSS Joins)

INNER JOIN
Matches only where both tables have the same non-NULL value.
Matching values:
Table1 has 1 twice → matches Table2’s 1 once → 2 rows
No other matching values (NULL does not match NULL)

All rows from Table1 + matching rows from Table2
(Unmatched rows from Table1 become NULL on right side)

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LEFT JOIN
Breakdown:

Table1 value	Matching Table2 rows	Count
1	1 match × occurs 2 times	2
2	0	1
5	0	1
NULL	NULL does not match NULL → 0	2

LEFT JOIN Result Count = 6
(because Table1 has 6 rows total)

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RIGHT JOIN

All rows from Table2 + matching rows from Table1
(Unmatched Table2 rows get NULL on left side)

Breakdown:

Table2 value	Matching Table1 rows	Count
3	0	2
4	0	2
1	Table1 has 1 twice → 2	2
NULL	no match	1

Total = 2 + 2 + 2 + 1 = 7
RIGHT JOIN Result Count = 7

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CROSS JOIN

All possible combinations of Table1 × Table2

• Table1 rows = 6
• Table2 rows = 6

CROSS JOIN Count = 6 × 6 = 36