SQL More Advanced

Question 1

UNION

Answer 1

Combines the results of two or more SELECT

The SELECT statements need to have the same number of columns. Columns must have similar types. Columns from each SELECT statement must be in the same order

SELECT column1, column2 FROM table
UNION
SELECT column3, column4 FROM table2;

Question 2

UNION ALL

Answer 2

Same as UNION but deduplicates.