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- SQL UNION clause is used to combine the two tables together. There will be 2 separate SELECT SQL’s those are combined using UNION clause.
- UNION selects records from both select queries and stores in a temporary result table. And then, UNION returns only distinct records from this temporary result table and displays in the output.
- All records are returned from both tables if there is no single duplicate record between them.
- I.e. SQL UNION removes duplicate records between 2 tables and selects only unique records from them.
- In the SQL UNION clause, both SELECT statements should have the same number of columns and in the same order and in similar data type.
SQL Syntax for UNION:
| SQL Syntax for UNION | SELECT column1, column2, etc FROM table1 UNION SELECT column1, column2, etc FROM table2; |
Please consider following 2 tables with few records as given below.
Table1:
Table name (for example): student1
Column names in this table: Student_ID, Student_name, City and Age
Available records: 4 rows
Table2:
Table name (for example): student2
Column names in this table: Student_ID, Department, College and Rank
Available records: 4 rows