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Introduction to Oracle UNION operator. The UNION operator is a set operator that combines result sets of two or more SELECT statements into a single result set. The following illustrates the syntax of the UNION operator that combines the result sets of two queries: SELECT. column_list_1.
14 Αυγ 2009 · SELECT name, MAX(Rcount) + MAX(Acount) AS TotalCount FROM ( SELECT name, COUNT(*) AS Rcount, 0 AS Acount FROM Results GROUP BY name UNION ALL SELECT name, 0, count(*) FROM Archive_Results GROUP BY name ) AS Both GROUP BY name ORDER BY name;
You can combine multiple queries using the set operators UNION, UNION ALL, INTERSECT, and MINUS. All set operators have equal precedence. If a SQL statement contains multiple set operators, then Oracle Database evaluates them from the left to right unless parentheses explicitly specify another order.
This SQL tutorial explains how to use the SQL UNION ALL operator with syntax and examples. The SQL UNION ALL operator is used to combine the result sets of 2 or more SELECT statements (does not remove duplicate rows).
SQL UNION ALL Example. The following SQL statement returns the cities (duplicate values also) from both the "Customers" and the "Suppliers" table: Example. SELECT City FROM Customers. UNION ALL. SELECT City FROM Suppliers. ORDER BY City; Try it Yourself »
19 Φεβ 2013 · with t(num, i) as ( select num, count from tab1 union all select num, i-1 from t where i >1 ) select num from t order by num; Here is a sqlfiddle demo
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:
