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Help Center/ Data Lake Insight/ SQL Syntax Reference (To Be Offline)/ Spark SQL Syntax Reference (Unavailable Soon)/ JOIN/ LEFT OUTER JOIN

LEFT OUTER JOIN

Updated on 2023-11-03 GMT+08:00

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Function

Join the left table with the right table and return all joined records of the left table. If no joined record is found, NULL will be returned.

Syntax

1 2	SELECT attr_expr_list FROM table_reference LEFT OUTER JOIN table_reference ON join_condition;

Keyword

LEFT OUTER JOIN: Returns all joined records of the left table. If no record is matched, NULL is returned.

Precautions

The to-be-joined table must exist. Otherwise, an error is reported.

Example

To join the courseId from the student_info table to the courseId from the course_info table for inner join and return the name of the students who have selected course, run the following statement. If no joined record is found, NULL will be returned.

1 2	SELECT student_info.name, course_info.courseName FROM student_info LEFT OUTER JOIN course_info ON (student_info.courseId = course_info.courseId);

Parent topic: JOIN

Previous topic: INNER JOIN

Next topic: RIGHT OUTER JOIN

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