To sum a UNION ALL subquery in Oracle, you can encapsulate the subquery within a larger query and use the SUM function to calculate the total of the result set. The UNION ALL operator is used to combine the results of multiple queries into a single result set. By using the SUM function on the encapsulating query, you can calculate the total sum of the combined subquery results. Remember to give an alias to the sum column to make it more readable in the output.
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What is the role of the having clause in filtering the sum result of a union all subquery in Oracle?
The HAVING clause is used in Oracle to filter the result set of a query based on specified conditions after the GROUP BY clause has been applied. In the context of a Union All subquery, the HAVING clause can be used to filter the sum result of the combined results from multiple queries.
For example, consider the following query:
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SELECT department_id, SUM(salary) as total_salary FROM employees GROUP BY department_id UNION ALL SELECT department_id, SUM(salary) as total_salary FROM temp_employees GROUP BY department_id HAVING total_salary > 10000; |
In this query, the UNION ALL operator is used to combine the results of two separate queries that calculate the total salary for each department. The HAVING clause is then used to filter the combined result set to only include departments with a total salary greater than 10000.
So, in summary, the HAVING clause in a query with a Union All subquery can be used to filter the sum result of the combined queries based on specific conditions.
What is the output format of the sum result in a union all subquery in Oracle?
The output format of the sum result in a union all subquery in Oracle is a single column containing the total sum of the values returned by the individual queries in the union all.
What is a union all subquery in Oracle?
A union all subquery in Oracle is a type of subquery that can be used within a main query to combine the results of multiple queries using the UNION ALL operator.
This type of subquery allows you to retrieve the result set of multiple queries and combine them into a single result set. The UNION ALL operator is used to combine the results with duplicates included, whereas the UNION operator removes duplicates.
For example, the following query uses a union all subquery to combine the results of two queries:
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SELECT column1, column2 FROM table1 UNION ALL SELECT column3, column4 FROM table2; |
In this example, the results of the two SELECT statements are combined using the UNION ALL operator, resulting in a single result set that includes all rows from both tables.
How to perform a sum operation on the result of a union all subquery in Oracle?
To perform a sum operation on the result of a UNION ALL subquery in Oracle, you can use the following SQL query:
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SELECT SUM(total_amount) FROM ( SELECT amount AS total_amount FROM table1 UNION ALL SELECT amount AS total_amount FROM table2 ) subquery_name; |
In this query:
- Replace amount with the column name that you want to sum from both tables.
- Replace table1 and table2 with the actual table names that you are querying.
- Replace subquery_name with a unique alias for the subquery.
This query will calculate the sum of the amount column from the result set of the UNION ALL subquery that combines data from table1 and table2.
