Let’s say you have a table with some data in it. You’ve found out that there is some duplicate data in this table. And you want to get rid of the duplicates. The way you define duplicate data could be dependant on your data. Is it a duplicate if all of the columns are the sa...
In this post we look at ways to remove all duplicate rows except one in an SQL database. For all examples in this article, we'll be using the following MySQL "user" table: +---+---+ | id | name | +
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Once you've defined which columns you need to check for duplicates, you can move on to step two. How to Find the Duplicates There are many ways you can find copies. Using group by is one of the easiest. To do this, list all the columns you identified in the previous step in the s...
Duplicate rows could be remove or drop from Spark SQL DataFrame using distinct() and dropDuplicates() functions, distinct() can be used to remove rows
To delete similar records, i.e. where the records are not the same but one field is the same and only one copy needs to be preserved, try the following SQL: delete T1 from MyTable T1, MyTable T2 where T1.dupField = T2.dupField ...
SQL select distinct on multiple columns is more useful in an RDBMS system to fetch unique records from various columns in a single table. We can use SQL to select distinct keywords on multiple columns from the specified table defined in the query. It will remove duplicate records from the col...
This time, we choose to insert more rows, but deliberately having the same title: -- Insert rows into table 'Book' INSERT INTO [dbo].[Book] ( -- Columns to insert data into [BookNumber], [Title], [Stock] ) VALUES ( -- First row: values for the columns in the list above ...
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You may use the below sample query to remove duplicate records.DELETE FROM your_table WHERE (unique_column1, unique_column2, created_at) IN (SELECT unique_column1, unique_column2, MAX(created_at)FROM your_tableGROUP BY unique_column1, unique_column2HAVING COUNT(*) > 1 );This SQL statem...