1. An inner join requires each row in the two joined tables to have matching column values, and is a commonly used join operation in applications but should not be assumed to be the best choice in all situations. Inner join creates a new result table by combining column values of two tables (A and B) based upon the join-predicate. The query compares each row of A with each row of B to find all pairs of rows which satisfy the join-predicate. When the join-predicate is satisfied by matching non-NULL values, column values for each matched pair of rows of A and B are combined into a result row.
2. The Inner Join keyword selects records that have matching values in both tables.
https://en.wikipedia.org/wiki/Join_(SQL)#Inner_join (1.); https://www.w3schools.com/sql/sql_join_inner.asp (2.)
Author: David Khedr