336x280(권장), 300x250(권장), 250x250, 200x200 크기의 광고 코드만 넣을 수 있습니다.
When a join condition is invalid or omitted completely, the result is a Cartesian product, in which all combinations of rows are displayed.
- No join condition is defined
- The employees table has 20 rows and the departments table has 8 rows, so the result will have 160 rows.
- All rows in the first table are joined to all rows in the second table.
- A cartesian product is formed when:
- A join coindition is omitted
- A join condition is invalid
- All rows in the first table are joined to all rows in the second table
- To avoid a Cartesian product, always include a valid condition.
ex) SELECT last_name, department_name, dept_name FROM employees, departments;
- No join condition is defined
- The employees table has 20 rows and the departments table has 8 rows, so the result will have 160 rows.
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