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. But Function is compiled and executed every time when it is called.
Basic Difference
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Function must return a value but in Stored Procedure it is optional( Procedure can return zero or n values).
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Functions can have only input parameters for it whereas Procedures can have input/output parameters .
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Function takes one input parameter it is mandatory but Stored Procedure may take o to n input parameters..
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Functions can be called from Procedure whereas Procedures cannot be called from Function.
Advance Difference
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Procedure allows SELECT as well as DML(INSERT/UPDATE/DELETE) statement in it whereas Function allows only SELECT statement in it.
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Procedures can not be utilized in a SELECT statement whereas Function can be embedded in a SELECT statement.
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Stored Procedures cannot be used in the SQL statements anywhere in the WHERE/HAVING/SELECT section whereas Function can be.
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Functions that return tables can be treated as another rowset. This can be used in JOINs with other tables.
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Inline Function can be though of as views that take parameters and can be used in JOINs and other Rowset operations.
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Exception can be handled by try-catch block in a Procedure whereas try-catch block cannot be used in a Function.
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We can go for Transaction Management in Procedure whereas we can’t go in Function.
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Stored Procedure
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Functions
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Compilation
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Stored in database in compiled format.
Note: Compiled indicates, Execution plan will be made by sql at the time it created and stored in DB.
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Will compiled at run time
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Return type
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It can directly return only integers
Return type is not must
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It can return any scalar or table
Return type is must
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Multiple return values
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It can also return more than one values (of any data type) indirectly with the help of out parameters
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It won’t support out parameters
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DML Statements
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Can have DML statements.
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Cannot have DML statements.
Note: In case of multi-table valued functions it can contain DML statements affecting Table Variables.
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Execution
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Stored procedure can execute function.
Cannot be the part of Select query as a column.
Stored Procedures cannot be used in the SQL statements anywhere in the WHERE/HAVING/SELECT
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Function cannot execute stored procedure.
Can be the part of select query as a column.
Functions be used in the SQL statements anywhere in the WHERE/HAVING/SELECT
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Exception handling
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Can have Try….Catch
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Cannot have Try….Catch
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