**SQL Aggregate Functions**

SQL aggregate functions return a single value, calculated from values in a column.

Useful aggregate functions:

AVG() - Returns the average value

COUNT() - Returns the number of rows

FIRST() - Returns the first value

LAST() - Returns the last value

MAX() - Returns the largest value

MIN() - Returns the smallest value

SUM() - Returns the sum

SQL scalar functions return a single value, based on the input value.

Useful scalar functions:

UCASE() - Converts a field to upper case

LCASE() - Converts a field to lower case

MID() - Extract characters from a text field

LEN() - Returns the length of a text field

ROUND() - Rounds a numeric field to the number of decimals specified

NOW() - Returns the current system date and time

FORMAT() - Formats how a field is to be displayed

AVG() - Returns the average value

COUNT() - Returns the number of rows

FIRST() - Returns the first value

LAST() - Returns the last value

MAX() - Returns the largest value

MIN() - Returns the smallest value

SUM() - Returns the sum

SQL Scalar functionsSQL Scalar functions

SQL scalar functions return a single value, based on the input value.

Useful scalar functions:

UCASE() - Converts a field to upper case

LCASE() - Converts a field to lower case

MID() - Extract characters from a text field

LEN() - Returns the length of a text field

ROUND() - Rounds a numeric field to the number of decimals specified

NOW() - Returns the current system date and time

FORMAT() - Formats how a field is to be displayed

Executing Scalar Function:

select dbo.ScalarFunctionName(@param1..)**Table-Valued Functions**

Table-Valued Functions have been around since SQL Server version 2005. Basically a Table-Valued Function is a function that returns a table, thus it can be used as a table in a query.

Executing Table-valued Function:

select * from dbo.TablevaluedfunctionName(@param1..)Example:

CREATE FUNCTION [dbo].[testFunction](@Itemvalue int)

returns @temptable TABLE (ID int IDENTITY(1,1),value int)

as

begin

set @Itemvalue=@Itemvalue+20

insert into @temptable(value) values(@Itemvalue)

return

end

select * from testFunction(50)

**Out put:**

ID value

1 70

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