SQL SUM Function
SQL > SQL Functions >
The SUM function is used to calculate the total for an expression.
The syntax for the SUM function is,
<expression> can be a column name or an arithmetic operation. An arithmetic operation can include more than one column, such as ("column1" - "column2").
It is also possible to have one or more columns in addition to the SUM function in the SELECT statement. In those cases, these columns need to be part of the GROUP BY clause as well:
SELECT "column_name1", "column_name2", ... "column_nameN", SUM("column_nameN+1")
GROUP BY "column_name1", "column_name2", ... "column_nameN";
We use the following table for our examples.
Example 1: SUM function on a column
To get the sum of all sales from Store_Information, we type in,
SELECT SUM(Sales) FROM Store_Information;
2750 represents the sum of all Sales entries: 1500 + 250 + 300 + 700.
Example 2: SUM function on an arithmetic operation
Assume that sales tax is 10% of the sales amount, we use the following SQL statement to get the total sales tax amount:
SELECT SUM(Sales*0.1) FROM Store_Information;
SQL will first calculate "Sales*0.1" and then apply the SUM function to the result.
Example 3: SUM function with a GROUP BY clause
To get the sum of sales for each store, we type in,
SELECT Store_Name, SUM(Sales) FROM Store_Information GROUP BY Store_Name;