Union All in SQL - sql - sql tutorial - learn sql
Difference Between Union Unionall Except Intersect
- The SQL UNION ALL operator is used to combine the result sets of 2 or more SELECT statements.
- It does not remove duplicate rows between the various SELECT statements (all rows are returned).
- Each SELECT statement within the UNION ALL must have the same number of fields in the result sets with similar data types.
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Syntax
- The syntax for UNION ALL is as follows:
[SQL Statement 1]
UNION ALL
[SQL Statement 2];
- The columns selected in [SQL Statement 1] and [SQL Statement 2] need to be of the same data type for UNION ALL to work.
Anatomy of a Union
SQL Union All Query
Example
- We use the following tables for our example.
Table Store_Information
| Store_Name | Sales | Txn_Date |
|---|---|---|
| Los Angeles | 1500 | Jan-05-1999 |
| San Diego | 250 | Jan-07-1999 |
| Los Angeles | 300 | Jan-08-1999 |
| Boston | 700 | Jan-08-1999 |
Table Internet_Sales
| Txn_Date | Sales |
|---|---|
| Jan-07-1999 | 250 |
| Jan-10-1999 | 535 |
| Jan-11-1999 | 320 |
| Jan-12-1999 | 750 |
- ยท To find out all the dates where there is a sales transaction at a store as well as all the dates where there is a sale over the internet, we use the following SQL statement:
SELECT Txn_Date FROM Store_Information
UNION ALL
SELECT Txn_Date FROM Internet_Sales;
Result:
| Txn_Date |
|---|
| Jan-05-1999 |
| Jan-07-1999 |
| Jan-08-1999 |
| Jan-08-1999 |
| Jan-07-1999 |
| Jan-10-1999 |
| Jan-11-1999 |
| Jan-12-1999 |
Union vs Union All