PRIMARY KEY vs UNIQUE KEY vs FOREIGN KEY - Part 3 | FOREIGN KEY CONSTRAINT | SELF REFERENCE KEY

PRIMARY KEY vs UNIQUE KEY vs FOREIGN KEY - Part 3 | FOREIGN KEY CONSTRAINT | SELF REFERENCE and CROSS-REFERENCE FOREIGN KEY PRIMARY KEY vs UNIQUE KEY, PRIMARY KEY vs FOREIGN KEY, PRIMARY KEY Constraint vs UNIQUE KEY Constraint, PRIMARY KEY Constraint vs FOREIGN KEY Constraint, Index vs Key, Unique Key vs Unique Index, Unique Clustered Index, non-clustered index, composite key, candidate key, alternate key, HEAP in SQL, Key vs Index, WITH CHECK vs WITH NOCHECK FOREIGN KEY Constraint, Non-clustered PRIMARY KEY, Clustered Unique Key, PRIMARY KEY vs UNIQUE KEY vs FOREIGN KEY, PRIMARY KEY Constraint, UNIQUE KEY Constraint, FOREIGN KEY Constraint Agenda: -------------- Q01. What is the use of FOREIGN KEY constraints? Q02. Can a unique constraint be referenced by a FOREIGN KEY Constraint? Q03. How many foreign keys you can create in a table? Q04. Can a FOREIGN KEY reference multiple columns of the parent table? Q05. Is NUll value allowed in the FOREIGN KEY column? Q06. Can a FOR