Jan 27, 2022 · Do you have unwanted duplicates from your SQL JOIN query? In this article, I’ll discuss the possible reasons for getting duplicates after joining tables in SQL and show how to fix a query depending on the reason behind the duplicates.

Here's a possible solution using unions: Set a manual field name identifying which table the rows come from so you can distinguish after the union, because the results will all look the same otherwise. I'm also assuming here that your r_req table has the same structure as the others.

Mar 10, 2023 · Removing duplicate data in SQL can help improve query performance and save storage space. By using the DISTINCT keyword, the GROUP BY clause, and the INNER JOIN statement, we can remove duplicates from a table in SQL.

Feb 15, 2016 · I tried this left outer join: SELECT S.NO, L.KEY FROM SHOP S LEFT OUTER JOIN LOCATN L ON S.NO = L.SHOP but I'm getting a lot of duplicates since there are many locations that belong to a single shop. I want to eliminate them and just get a list of "shop, key" entries without duplicates. The data is correct but duplicates appear as follows:

Oct 23, 2012 · SELECT News.ID, News.Title, News.Description FROM News WHERE EXISTS (SELECT NULL FROM NewsType INNER JOIN Type ON NewsType.Type_ID = Type.ID WHERE News.ID = NewsType.News_ID AND Type.Type_Code = @typeCode)

Aug 16, 2011 · In the above simple situation, how can I remove duplicates in the following query? I want to compare firstname and lastname, if they match, I return firstname, lastname and recid from table2. SELECT DISTINCT * FROM (SELECT recid, first, last FROM table1) a INNER JOIN (SELECT recid, first,last FROM table2) b ON a.first = b.first

Oct 29, 2024 · Explore the different methods for filtering out and permanently removing duplicate rows using SQL. Learn the practical applications of how to remove duplicates in SQL Server, MySQL, and PostgreSQL.

Jul 30, 2024 · To delete duplicates, we can use a self-join to compare the rows and only keep one instance of each duplicate group: DELETE r1 FROM Registration r1 INNER JOIN Registration r2 WHERE r1.semester = r2.semester AND r1.year = r2.year AND r1.course_id = r2.course_id AND r1.student_id = r2.student_id AND r1.id > r2.id;

Oct 19, 2023 · In SQL, you can delete duplicate records from multiple tables using a single SQL query by using subqueries and the DELETE statement. This approach allows you to identify and remove duplicate entries across multiple tables efficiently. Here's an example that demonstrates how to delete duplicate records from multiple tables:

Jan 13, 2013 · I want to join both tables, and remove entries with same name and postal code. I found some answers on how to do it but they were too complicated. i think you want UNION. what is your desired output? You can use UNION clause, UNION will check for duplicates and only distinct rows will be returned.