count_if aggregate function

Returns the number of true values for the group in expr.

Syntax 

count_if ( [ALL | DISTINCT] expr ) [FILTER ( WHERE cond ) ]

Arguments

  • expr: A BOOLEAN expression.

  • cond: An optional boolean expression filtering the rows used for aggregation.

Returns

A BIGINT.

count_if(expr) FILTER(WHERE cond) is equivalent to count_if(expr AND cond).

If DISTINCT is specified only unique rows are counted.

Examples 

> SELECT count_if(col % 2 = 0) FROM VALUES (NULL), (0), (1), (2), (2), (3) AS tab(col);
 3
> SELECT count_if(DISTINCT col % 2 = 0) FROM VALUES (NULL), (0), (1), (2), (2), (3) AS tab(col);
 2
> SELECT count_if(col IS NULL) FROM VALUES (NULL), (0), (1), (2), (3) AS tab(col);
 1