Said SalomonUnitrin Direct Insurance

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T-SQL Aggregate FunctionsSaid Salomon

Who am I?

I have over 25 year experience IT.  I have a vast array of abilities in the field in the areas of Network, Desktop Support, DBA, Staff Project Management, Application Software Development, Business Analysis and Quality Assurance.   I have Microsoft certifications as MCTS, MCPS, and MCNPS, and multiple certifications from the Insurance Institute of America. Currently I am a DBA at Unitrin Direct Insurance.

Aggregate Functions

AVG MIN

CHECKSUM_AGG SUM

COUNT STDEV

COUNT_BIG STDEVP

GROUPING VAR

MAX VARP

AVG

Returns the average of the values in a group. Syntax:

AVG ( [ ALL | DISTINCT ] expression ) All

Applies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that AVG be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

CHECKSUM_AGG

Returns the checksum of the values in a group. Syntax:

CHECKSUM_AGG ( [ ALL | DISTINCT ] expression ) All

Applies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that CHECKSUM_AGG be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

COUNT

Returns the number of items in a group. Syntax:

COUNT ( { [ [ ALL | DISTINCT ] expression ] | * } ) All

Applies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that COUNT be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

*Specifies that all rows should be counted to return the total number of rows in a table.

COUNT_BIG

Same as Count expect it returns bigint

GROUPING

Indicates whether a specified column expression in a GROUP BY list is aggregated or not.

Syntax:GROUPING ( <column_expression> )

column_expressionIs a column or an expression that contains a column in a GROUP BY clause.

MAX

Returns the maximum value in the expression. Syntax:

MAX ( [ ALL | DISTINCT ] expression ) All

Applies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that MAX be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

MIN

Returns the minimum value in the expression. Syntax:

MIN ( [ ALL | DISTINCT ] expression ) All

Applies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that MIN be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

SUM

Returns the sum of all the values. Syntax:

SUM ( [ ALL | DISTINCT ] expression ) All

Applies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that SUM be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

STDEV

Returns the statistical standard deviation of all values in the specified expression.

Syntax:STDEV ( [ ALL | DISTINCT ] expression )

AllApplies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that STDEV be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

STDEVP

Returns the statistical standard deviation for the population for all values in the specified expression.

Syntax:STDEVP ( [ ALL | DISTINCT ] expression )

AllApplies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that STDEVP be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

VAR

Returns the statistical variance of all values in the specified expression.

Syntax:VAR ( [ ALL | DISTINCT ] expression )

AllApplies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that VAR be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

VARP

Returns the statistical variance for the population for all values in the specified expression.

Syntax:VARP ( [ ALL | DISTINCT ] expression )

AllApplies the aggregate function to all values. ALL is the default.

DISTINCTSpecifies that VARP be performed only on each unique instance of a value, regardless of how many times the value occurs.

ExpressionIs an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

Resources

Aggregate Functions (books Online) http://bit.ly/dAaXRl

SQL Server 2008, Dev Edition http://bit.ly/L2hJQ

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