SUM
Calculates the sum of an expression.
Syntax
SUM ([DISTINCT] <expr>)
Parameter | Description |
---|---|
<expr> | The expression used to calculate the sum. Valid values for <expr> include column names or expressions that evaluate to numeric values. |
DISTINCT | When specified, removes duplicate values from <expr> before calculating the sum. |
Example
Consider a table test_scores
with the following columns.
+———–+——-+ | firstname | score | +———–+——-+ | Deborah | 90 | | Albert | 50 | | Carol | 11 | | Frank | 87 | | Thomas | 85 | | Peter | 50 | | Sammy | 90 | | Humphrey | 56 | +———–+——-+
SELECT
SUM(score)
FROM
test_scores
Returns: 519
SELECT
SUM (DISTINCT score)
FROM
test_scores
One each of the duplicated 90
and 50
scores are removed from the calculation.
Returns: 379