LEFT JOIN, I have a conditional question.

Asked 2 years ago, Updated 2 years ago, 23 views

SELECT *
FROM Reference Table A
  LEFT JOIN Table BON A.no = B.no
                                       AND A.no > 10
                                       AND B.no > 15

WHERE ...

As in the example above, in the case of LEFT JOIN, I understand that the condition of the reference table (A) is not applied to the ON section. I wonder why it's not working.

sql

2022-09-22 20:23

1 Answers

LEFT OUTER JOIN reads the data corresponding to the left table marked first when performing the join, and then reads the JOIN target data from the right table marked later. In other words, when there are tables A and B, A is the reference, and the two are compared, and the same value is obtained from the JOIN column of B, and if there is no same value, fill it with the NULL value. It's the same as LEFT JOIN. [Source] CROSS JOIN & OUTER JOIN|Author Choi Min-jin


2022-09-22 20:23

If you have any answers or tips


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