ERROR: function avg(boolean) does not exist

Question

I am trying to know how frequently an event happens, and the occurence of this event in my database is recorded by setting a boolean to 'TRUE' and the non-occurence is setting it to 'FALSE'.

But when I am try to select the value by using the function avg() it returns me this error: ERROR: function avg(boolean) does not exist

How can I measure the event frequency and at the some time keep a good performance ?

Thank you.

Joao

Answer 1

This will coerce the value into 0's and 1's

select avg(val::int);

Answer 2

You could do this:

AVG(CASE WHEN  myBooleanAttribute = TRUE THEN 1 ELSE 0 END)

Answer 3

If you cast as int you will get an int average, which isnt very useful. Instead try:

select avg(val::int::float4);