![]() Rename the immediate table to the name of the source table. ![]() Insert distinct rows from the source table to the immediate table.Create a new table with the same structure as the one whose duplicate rows should be removed.To delete rows using an immediate table, you use the following steps: Deleting duplicate rows using an immediate table In this case, the statement will delete all rows with duplicate values in the column_1 and column_2 columns. ROW_NUMBER() OVER( PARTITION BY column_1, In case you want to delete duplicate based on values of multiple columns, here is the query template: DELETE FROM table_name WHERE id IN If you want to keep the duplicate row with highest id, just change the order in the subquery: DELETE FROM basket And the outer DELETE statement deleted the duplicate rows returned by the subquery. In this example, the subquery returned the duplicate rows except for the first row in the duplicate group. WHERE t.row_num > 1 ) Code language: PostgreSQL SQL dialect and PL/pgSQL ( pgsql ) The following statement uses a suquery to delete duplicate rows and keep the row with the lowest id. Perfect! the duplicate rows with the lowest ids are retained. To check whether the statement works correctly, let’s verify the data in the basket table: SELECT The following statement uses the DELETE USING statement to remove duplicate rows: DELETE FROMĪND a.fruit = b.fruit Code language: PostgreSQL SQL dialect and PL/pgSQL ( pgsql ) The find the duplicate rows, you use the following statement: SELECTįruit Code language: PostgreSQL SQL dialect and PL/pgSQL ( pgsql ) Deleting duplicate rows using DELETE USING statement However, it is not the case with the big table. If the table has few rows, you can see which ones are duplicate immediately. Third, query data from the basket table: SELECTīasket Code language: PostgreSQL SQL dialect and PL/pgSQL ( pgsql )Īs you can see, we have some duplicate rows such as 2 apples and 3 oranges in the basket table. INSERT INTO basket(fruit) values( 'banana') Code language: PostgreSQL SQL dialect and PL/pgSQL ( pgsql ) INSERT INTO basket(fruit) values( 'orange') INSERT INTO basket(fruit) values( 'apple') Second, insert some fruits into the basket table. ) Code language: PostgreSQL SQL dialect and PL/pgSQL ( pgsql ) Preparing sample dataįirst, create a new table named basket that stores fruits: CREATE TABLE basket( I hope this will help the readers.Summary: in this tutorial, you will learn how to use various techniques to delete duplicate rows in PostgreSQL. In this article, we have learned how to find and delete duplicate values in a table by using the “Group By and Having” clause, “Common Table Expressions (CTE),” and “Rank” function in SQL Server. To delete duplicate records here also have to add a “Where” clause with the condition “ > 1”. The above query “” column gives a unique row id for each duplicate row, like the CTE query. INNER JOIN (SELECT *, RANK() OVER(PARTITION BY, ORDER BY ) AS įROM. Here we will use the Rank function, the “PARTITION BY” clause, and “INNER JOIN.” SELECT e., e., e., t. We can also delete duplicate records by using the “Rank()” function. ![]() The above query deletes all duplicate records with “” greater than 1. If we want to delete duplicate records using CTE, then we have to add a “Where” clause with the condition “ > 1”. The above query “” column gives a unique row id for each duplicate row. WITH CTE(,, )ĪS (SELECT, , ROW_NUMBER() OVER(PARTITION BY, ORDER BY ) AS CTE is available in SQL Server 2005 or higher version. ![]() We use the “Row_Number” function and Common Table Expressions to find duplicate values. GROUP BY, ) By Using Common Table Expressions (CTE) To delete the duplicate records, we can use the below query. In the above query, we will exclude the minimum id of each duplicate row. We can use the “MIN” function to get the first record of all duplicate records. Now we need to keep one record and delete all duplicate records. In the above query, we will get all data having duplicated more than one, and the “” column shows how many duplicate records there are. We can use the COUNT function.įor example, SELECT, , = COUNT(*) VALUES('Malaya Kabiraj', 'Kolkata') By Using Group By and Having a clauseīy using Group By clause, we can group all table data as per our defined columns and count the duplicate occurrence of rows. In this article, we will find duplicate values using the "Group By and Having" clause, "Common Table Expressions (CTE)," and "Rank" function.įor this operation, we will create a table named “employee” and add some records. This article will teach us how to find and delete duplicate values from a SQL server table. Sometimes we may find duplicate values in a table, and we have to find the duplicate values from that table.
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