Answer»
A function that performs an arithmetic operation on a set of values and returns a single value is called an aggregate function.
| COMMAND | FUNCTION | SYNTAX |
|---|
| count() | Returns the number of rows, (including NULL) |
>SELECT COUNT(COLUMN_NAME)
FROM TABLE_NAME
WHERE CONDITION; | | sum() | Returns sum of all non NULL values. |
>SELECT SUM(COLUMN_NAME)
FROM TABLE_NAME
WHERE CONDITION; | | avg() | Returns average of all non NULL values. |
>SELECT AVG(COLUMN_NAME)
FROM TABLE_NAME
WHERE CONDITION; | | min() | Returns minimum value in the set. |
>SELECT MIN(COLUMN_NAME)
FROM TABLE_NAME
WHERE CONDITION; | | max() | Returns maximum value in the set. |
>SELECT MAX(COLUMN_NAME)
FROM TABLE_NAME
WHERE CONDITION; | | groutp_concat() | Concatenates values from multiple rows into one field. |
>SELECT COLUMN1, COLUMN2, ...
GROUP_CONCAT ( DISTINCTCOLUMN1
ORDER BY .. )
FROM TABLE_NAME GROUP BY COLUMN2; |
|
