What does UNION do in SQL query?

The SQL UNION Operator The UNION operator is used to combine the result-set of two or more SELECT statements.

Can we use union in SQL?

The SQL UNION operator is used to combine the result sets of 2 or more SELECT statements. It removes duplicate rows between the various SELECT statements. Each SELECT statement within the UNION must have the same number of fields in the result sets with similar data types.

What is Union in SQL with example?

The SQL UNION clause/operator is used to combine the results of two or more SELECT statements without returning any duplicate rows. To use this UNION clause, each SELECT statement must have. The same number of columns selected. The same number of column expressions. The same data type and.

How do you UNION a query?

Click the tab for the union query that you started to create earlier. Paste the SQL statement for the select query into the SQL view object tab of the union query. Delete the semicolon (;) at the end of the select query SQL statement. Press Enter to move the cursor down one line, and then type UNION on the new line.

What can I use instead of union in SQL?

There are several alternatives to the union SQL operator:

  • Use UNION ALL.
  • Execute each SQL separately and merge and sort the result sets within your program!
  • Join the tables.
  • In versions, 10g and beyond, explore the MODEL clause.
  • Use a scalar subquery.

What is faster join or UNION?

Union will be faster, as it simply passes the first SELECT statement, and then parses the second SELECT statement and adds the results to the end of the output table.

Does Union in SQL remove duplicates?

SQL Union All Operator Overview The SQL Union All operator combines the result of two or more Select statement similar to a SQL Union operator with a difference. The only difference is that it does not remove any duplicate rows from the output of the Select statement.

Is UNION same as full outer join?

Answers. Union is vertical – rows from table1 followed by rows from table2 (distinct for union, all for union all) and both table must have same number of columns with compatible datatypes. Full outer join is horizontal.