Question

What is SQL Functions and what are their different types?

Answer

Function:- Function in a database can be defined as the code segment consisting of a logical group of SQL statements which takes some input arguments (if required), run in a sequential order and returns the output either in the form of a single value or in the form of a table.

In SQL, Functions can be categorized into two categories:-

1. System Defined Function
2. User Defined Function (UDF)

System defined function can again be further divided into further subsections which are given below:-

1. Aggregate function. Example: - Avg (), Min (), Max ()

2. Configuration function. Example:-@@servername (), @@version()

3. Cursor function. Example: -@@Fetch_status

4. Date and Time function. Example: - Getdate (), Month (), Day (), Year ()

5. Mathematical function. Example: - Floor (), Abs ()

6. Metadata function. Example: - DbName (), FileName ()

7. Other functions. Example: - cast (), convert ()

8. Rowset function. Example: - Openxml (), Openrowset ()

9. Security function. Example:-user(), UserId (), UserName ()

10. String function. Example: - Char (), Left (), Len ()

11. System Statistical function. Example:-@@connections

12. Text and Image function Example: - Textvalid ()

Types of UDF:-

Similarly, UDF can be divided Into 3 categories:-

1. Scalar UDF

2. Inline Table UDF

3. Multi statements UDF

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