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written 5.8 years ago by |

**SQL Functions**

SQL provides many built-in functions to perform operations on data. These functions are useful while performing Mathematical calculations, string concatenations, sub-strings etc.

SQL functions are divided into two catagories,

- Aggregrate Functions
- Scalar Functions

**Aggregrate Functions:**

These functions return a single value after calculating from a group of values. Following are some frequently used Aggregrate functions.

**AVG()**

Average returns average value after calculating from values in a numeric column. Its general Syntax is,

*SELECT AVG(column_name) from table_name*

*Example using AVG()*

**COUNT()**

Count returns the number of rows present in the table either based on some condition or without condition. Its general Syntax is,

*SELECT COUNT(column_name) from table-name*

*Example using COUNT()*

**FIRST()**

First function returns first value of a selected column. Syntax for FIRST function is,

*SELECT FIRST(column_name) from table-name*

*Example of FIRST()*

**LAST()**

LAST return the return last value from selected column. Syntax of LAST function is,

*SELECT LAST(column_name) from table-name*
*Example of LAST()*

**MAX()**

MAX function returns maximum value from selected column of the table. Syntax of MAX function is,

*SELECT MAX(column_name) from table-name*

*Example of MAX()*

**MIN()**

MIN function returns minimum value from a selected column of the table. Syntax for MIN function is,

*SELECT MIN(column_name) from table-name*

*Example of MIN()*

**SUM()**

SUM function returns total sum of a selected columns numeric values. Syntax for SUM is,

*SELECT SUM(column_name) from table-name*

*Example of SUM()*

**Scalar Functions:**

Scalar functions return a single value from an input value. Following are some frequently used Scalar Functions.

**UCASE()**

UCASE function is used to convert value of string column to Uppercase character.

Syntax of UCASE,

*SELECT UCASE(column_name) from table-name*

*Example of UCASE()*

**LCASE()**

LCASE function is used to convert value of string column to Lowecase character.

Syntax for LCASE is,

*SELECT LCASE(column_name) from table-name*

*Example of LCASE()*

**MID()**

MID function is used to extract substrings from column values of string type in a table.

Syntax for MID function is,

*SELECT MID(column_name, start, length) from table-name*

**ROUND()**

ROUND function is used to round a numeric field to number of nearest integer. It is used on Decimal point values.

Syntax of Round function is

*SELECT ROUND(column_name, decimals) from table-name*