COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM INVOICES WHERE CustomerName = 'NewTech Industries'

COUNT(DISTINCT)

Returns the number of distinct, non-null field values matching the query criteria.

SELECT COUNT(DISTINCT InvoiceId) AS DistinctValues FROM INVOICES WHERE CustomerName = 'NewTech Industries'

AVG

Returns the average of the column values.

SELECT InvoiceNumber, AVG(AnnualRevenue) FROM INVOICES WHERE CustomerName = 'NewTech Industries'  GROUP BY InvoiceNumber

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), InvoiceNumber FROM INVOICES WHERE CustomerName = 'NewTech Industries' GROUP BY InvoiceNumber

MAX

Returns the maximum column value.

SELECT InvoiceNumber, MAX(AnnualRevenue) FROM INVOICES WHERE CustomerName = 'NewTech Industries' GROUP BY InvoiceNumber

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM INVOICES WHERE CustomerName = 'NewTech Industries'