COUNT0

Returns the count of all values respecting the parameters given in the expression.
Syntax:
SELECT COUNT([DISTINCT] column [WHERE filtercolumn=value_to_test OR filtercolumn=another_value_to_test]) FROM table
Examples:
/* returns the number of distinct id's from the table transactions /SELECT COUNT(DISTINCT id) FROM transactions   / returns the number of distinct ids in column one and the number of distinct ids where the column chain=2 please note that this expression can be used in the datamodeler by simply typing the WHERE clause after the columnname. */ SELECT COUNT(DISTINCT id) AS distinctids, COUNT(DISTINCT id WHERE chain=2) AS distinctidchain2 FROM transactions.