Infosys Software Tester Interview Questions, Process, and Tips

Union combines and removes duplicates, Union All combines all rows including duplicates.

• Union merges two or more tables and removes duplicate rows.

• Union All merges two or more tables and includes all rows, including duplicates.

• Union is slower than Union All as it requires removing duplicates.

• Example: SELECT column1 FROM table1 UNION SELECT column1 FROM table2;

• Example: SELECT column1 FROM table1 UNION ALL SELECT column1