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The UNION ALL command combines the result set of two or more SELECT statements (allows duplicate values). The following SQL statement returns the cities (duplicate values also) from both the "Customers" and the "Suppliers" table: SQL Keywords Reference.
- SQL Union
UNION ALL Syntax. The UNION operator selects only distinct...
- SQL Union
UNION ALL Syntax. The UNION operator selects only distinct values by default. To allow duplicate values, use UNION ALL:
8 wrz 2008 · Both UNION and UNION ALL concatenate the result of two different SQLs. They differ in the way they handle duplicates. UNION performs a DISTINCT on the result set, eliminating any duplicate rows. UNION ALL does not remove duplicates, and it therefore faster than UNION.
9 wrz 2024 · UNION ALL command helps us to combine results of two or more SELECT statements from different tables. The UNION ALL command includes the duplicate records from the SELECT statements whereas the UNION command does not include duplicate records otherwise both the commands are same.
When to use UNION ALL. Use UNION ALL when you want to combine all results, including duplicates, or when you know there won't be any duplicates and want better performance. It's ideal for: Combining log data from multiple sources; Aggregating data where duplicates are important; Merging data from non-overlapping datasets
Let us discuss how to use union operator in oracle sql server with example.
5 sty 2023 · If no (or if it doesn’t matter), use UNION ALL. That was a lot, so let’s take some time to review! Both UNION and UNION ALL are clauses used to combine multiple queries into one result set. UNION will remove duplicates, while UNION ALL will not. UNION ALL runs faster because of this.
