![]() ![]() The following statement illustrates the syntax of the DISTINCT clause: SELECT. (T2.RDB$DB_KEY > T1.RDB$DB_KEY)) In this case, we are using physical RDB$DB_KEY to distinguish 2 records with identical contents in specified fields (column1, column1, etc), and record with the bigger RDB$DB_KEY. The DISTINCT clause allows you to remove the duplicate rows in the result set. (T2.column2 = T1.column2 or (T2.column2 is null and T2.column2 is null)) AND (T2.column1 = T1.column1 or (T2.column1 is null and T2.column1 is null)) AND To do it, we need to use RDB$DB_KEY - an implicit physical record number in Firebird database, it can be used to create an artificial difference between identical records. Before deleting any data You can’t undo data deletions, so make sure your database is ready before you try to delete duplicate records: Make sure that the file is not read-only. We will loop through list of schema and table and. ![]() To overcome with this problem we use DISTINCT keyword. You make sure that you are fetching unique records instead of fetching duplicate records. Note: The methods described in this article do not apply to Access web apps. As we need to find the duplicate records in all the tables, we need loop. If you have got a situation that you have multiple duplicate records in a table, so at the time of fetching records from the table you should be more careful. Usually, we want to leave one of the duplicates and delete others. The first step is to Find duplicate records with a query in your database. Then, we can use the DELETE statement to remove the duplicate. How to find and delete duplicate records in Firebird databaseĭELETE command (as it is defined in SQL standard) always deletes all records which satisfy the condition. First, we need to find the duplicate rows using the GROUP BY clause or the ROWNUMBER() function. ![]()
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