Welcome to Lesson 13 of the TSQL Tutorial. In this lesson we will cover select group by statements. I hope you enjoy the lesson.

Select Statements

In the first lesson we showed how to use the select statement. In this lesson we will build on the select statement by grouping items together. All items in the select statement must either be contained in a group by clause or in an aggregate function (i.e. count, sum, etc...)

Usage:

SELECT column(s)

FROM table
GROUP BY field

Example:

SELECT count(EmployeeID), Title

FROM employees
GROUP BY Title

Results:

	Title
6	Sales Representative
1	Vice President, Sales
1	Sales Manager
1	Inside Sales Coordinator

Aggregate functions in SQL Server

Function	Description
AVG(column)	Returns the average value of a column
BINARY_CHECKSUM
CHECKSUM
CHECKSUM_AGG
COUNT(column)	Returns the number of rows (without a NULL value) of a column
COUNT(*)	Returns the number of selected rows
COUNT(DISTINCT column)	Returns the number of distinct results
FIRST(column)	Returns the value of the first record in a specified field (not supported in SQLServer2K)
LAST(column)	Returns the value of the last record in a specified field (not supported in SQLServer2K)
MAX(column)	Returns the highest value of a column
MIN(column)	Returns the lowest value of a column
STDEV(column)
STDEVP(column)
SUM(column)	Returns the total sum of a column
VAR(column)
VARP(column)