Скачать или смотреть How to Retrieve Related member Records by semester Using MySQL Joins

Learn how to efficiently query members belonging to specific semesters by using JOINs in MySQL to filter records from related tables.
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This video is based on the question https://stackoverflow.com/q/79502695/ asked by the user 'Buddhika Athukorala' ( https://stackoverflow.com/u/3252100/ ) and on the answer https://stackoverflow.com/a/79502710/ provided by the user 'Vansh Patel' ( https://stackoverflow.com/u/19021603/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Problem Overview

You have three tables: member, semester, and member_semester. Each member may be linked to multiple semesters through the member_semester table. You want to:

Get members belonging only to semester 552

Get members belonging only to semester 553

Get members belonging to either or both semesters 552 and 553

Table Structure Summary

member: Contains member details (id, name, status)

semester: Contains semester info (id, name)

member_semester: Links members to semesters (id, semester, member, status)

Solution: Use SQL JOIN and Filtering

You can achieve this by joining member_semester with member on the member id and filtering by the semester.

1. Get Members in Semester 552

[[See Video to Reveal this Text or Code Snippet]]

Replace 552 with 553 to get members for semester 553.

2. Get Members in Semesters 552 or 553

Use the IN clause to filter multiple semesters:

[[See Video to Reveal this Text or Code Snippet]]

This query returns all members enrolled in either semester 552 or 553.

Key Points

Use INNER JOIN to combine member details with their semester relations.

Use WHERE or IN to filter the semesters you want.

Explicitly select columns to avoid ambiguity, especially when joining tables having columns with the same name.

This approach is both clear and efficient for querying related records across multiple tables.