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8 lis 2010 · Using UNION automatically removes duplicate rows unless you specify UNION ALL: http://msdn.microsoft.com/en-us/library/ms180026(SQL.90).aspx
The UNION operator selects only distinct values by default. To allow duplicate values, use UNION ALL: SELECT column_name (s) FROM table1. UNION ALL. SELECT column_name (s) FROM table2; Note: The column names in the result-set are usually equal to the column names in the first SELECT statement.
Operacje EXCEPT, INTERSECT, UNION w SQL. Jak wyznaczać różnice, część wspólną i sumę zbiorów w SQL z usunięciem i zachowaniem duplikatów
19 wrz 2018 · In this post, I am going to show you a tricky method of removing duplicate rows using traditional UNION operator. In my earlier post on SQL SERVER – Delete Duplicate Rows, I showed you a method of removing duplicate rows with the help of ROW_NUMBER() function and COMMON TABLE EXPRESSION.
23 maj 2023 · The first example uses UNION ALL to show duplicated records and returns each row in the source table three times. The second example uses UNION without ALL to eliminate the duplicate rows from the combined results of the three SELECT statements and returns only the unduplicated rows from the source table.
18 cze 2024 · The UNION operation in SQL combines the results of two or more SELECT queries into a single distinct result set. It removes duplicate rows from the final result, ensuring each row appears only once. The basic syntax for the UNION operation is: SELECT column1, column2, column3 FROM table1 UNION SELECT column1, column2, column3 FROM table2;
By default, the UNION operator removes all duplicate rows from the result sets. However, if you want to retain the duplicate rows, you need to specify the ALL keyword is explicitly as shown below: query_1. UNION ALL. query_2. Code language: SQL (Structured Query Language) (sql)
