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This tutorial shows you how to use the Oracle UNION to combine result sets of multiple queries. The UNION removes duplicate while the UNION ALL does not.
25 Σεπ 2013 · select groupname, sum(jobs), sum(cpu), 0, 0 from tbl. where subsys = 'NORM'. group by groupname. union all. select groupname, 0, 0, sum(jobs), sum(cpu) from tbl. where subsys = 'SYS7'. group by groupname. Unfortunately, our new solution does not allow post-processing and it all has to be done in the SQL query.
The UNION operator returns only distinct rows that appear in either result, while the UNION ALL operator returns all rows. The UNION ALL operator does not eliminate duplicate selected rows:
This Oracle tutorial explains how to use the Oracle UNION ALL operator with syntax and examples. The Oracle UNION ALL operator is used to combine the result sets of 2 or more SELECT statements (does not remove duplicate rows).
UNION ALL Example The UNION operator returns only distinct rows that appear in either result, while the UNION ALL operator returns all rows. The UNION ALL operator does not eliminate duplicate selected rows: SELECT product_id FROM order_items UNION SELECT product_id FROM inventories; SELECT location_id FROM locations UNION ALL SELECT location ...
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.
8 Αυγ 2019 · The way UNION is designed to work according to Oracle: "You can combine multiple queries using the set operators UNION, UNION ALL, INTERSECT, and MINUS." In other words, you need to HAVE multiple queries in order to UNION them.
