Differences

1. Difference between Primary Key and Unique Key

SN.	Primary Key	Unique Key
1	Only one Primary key allowed in a table.	More than one unique key allowed in a table
2	By default, Primary key is clustered index and data in the database table is physically organized in the sequence of clustered index.	By default, Unique key is non-clustered index.
3	Primary Key can't accept null values.	Unique key can accept only one null value.
4	Primary key can be made foreign key into another table.	Unique key can't be made foreign key into another table.

2. Difference between Stored Procedure and Function

SN.	Function	Procedure
1	Function must return a value.	Stored Procedure it is optional
2	Functions can have only input parameters for it	Procedures can have input/output parameters.
3	Function takes one input parameter it is mandatory	Stored Procedure may take o to n input parameters.
4	Functions can be called from Procedure	Procedures cannot be called from Function
5	Function is compiled and executed every time it is called.	Stored Procedures are pre-compile objects which are compiled for first time and its compiled format is saved which executes (compiled code) whenever it is called
6	Function allows only SELECT statement in it.	Procedure allows SELECT as well as DML (INSERT/UPDATE/DELETE) Query.
7	try-catch block cannot be used in a Function.	Exception can be handled by try-catch block in a Procedure
Other Differences 1.  Stored Procedures cannot be used in the SQL statements anywhere in the WHERE/HAVING/SELECT section whereas Function can be. 2.  Functions that return tables can be treated as another rowset. This can be used in JOINs with other tables. 3.  Inline Function can be thought of as views that take parameters and can be used in JOINs and other rowset operations. 4.  We can go for Transaction Management in Procedure whereas we can't go in Function.