The CAST function converts the semantic type of a field or expression to text or number.In this article:
CAST(num AS TEXT) CAST(timestamp_str AS NUMBER)
CAST(field_expression AS type)
TEXT—convert the input to text.
NUMBER—convert the input to a number.
Goal: count website sessions longer than N seconds.
In a Google Analytics data source, Session Duration is a text dimension. The first step to counting sessions longer than N is to convert this to a number using CAST. The second step is to use the CASE statement to identify sessions longer than a certain value—we'll say 60 seconds for this example. We'll combine CASE with SUM to do the counting.
Step 1: Create a new calculated field Session Duration (number) with the following formula:
CAST(Session Duration AS NUMBER)
Step 2: Create a new calculated field Long Sessions:
SUM(CASE WHEN Session Duration > 60 THEN 1 ELSE 0 END)
You cannot CAST aggregated fields.