To understand the concept of equijoin, the user should know the basics of SQL and joins. An equijoin is a type of join that combines columns from two or more tables based on their equality.
Let's go through each option and explain whether it is true or false:
A. You can join a maximum of two tables through an equijoin
This statement is false. You can join more than two tables through an equijoin.
B. You can join a maximum of two columns through an equijoin
This statement is false. You can join more than two columns through an equijoin.
C. You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement
This statement is false. You specify an equijoin condition in the WHERE clause of a SELECT statement.
D. To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.
This statement is false. The columns in the join condition need not be primary key and foreign key columns; they can be any columns that have the same data type and contain the same values.
E. You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.
This statement is true. If you want to join n tables, you need to specify a minimum of n-1 join conditions.