University:
American Baptist College
Course:
CSCI 1534 | Data Analysis and Visualization
Academic year:

2023
Views:

42

Pages:

2
Author:

Muthia M.

Data Retrieval UNION UNION clause/operator is used to combine the results of two or more SELECT statements without returning any duplicate rows. In SQL, when you use UNION, it takes the results from two SELECT queries and puts them together into one list, making sure there are no repeated values in the final list. SELECT column_1, column_2 FROM table_1 [WHERE condition] UNION SELECT column_1, column_2 FROM table_2 [WHERE condition] Data Retrieval UNION ALL Command combines the result set of two or more SELECT statements (allows duplicate values). In SQL, UNION ALL is like an upgraded version of UNION. While UNION only gives you unique values from two tables, UNION ALL gives you everything, including duplicates. It combines the results of multiple SELECT queries, showing all the values, even if they're repeated. SELECT column_names FROM table_1 WHERE conditions UNION ALL SELECT column_names FROM table_2 WHERE conditions;