COUNT( ) 回傳筆數

SQL COUNT(column_name) Syntax

returns the number of values (NULL values will not be counted) of the specified column

SELECT COUNT(column_name) FROM table_name

The COUNT(*) function returns the number of records in a table:

SELECT COUNT(*) FROM table_name

O_Id	OrderDate	Price	顧客
1	20011/11/12	100	ans
2	20011/11/12	100	dce
3	20011/11/14	100	abc
4	20011/11/15	100	ans

尋找顧客ans購買次數：

SELECT COUNT(顧客) AS CustomerNilsen FROM Orders
WHERE 顧客='ans'