Package com.im.df.api.capabilities

Interface DFFieldFunctionCapability.Function

    • Method Detail

      • getSelectSQL

        java.lang.String getSelectSQL()
        Get the SQL that retrieves the values. This will be addded to the SELECT clause. In the case of a simple function that only uses columns from the main table this can just be the simple function e.g. "col1 + col2", but if the function is more complex (e.g. using columns from other tables) then it can be a sub-select e.g. "(SELECT avg(wombat_act_list.value_min)" (you must provide the outer brackets).
        Returns:
        The SQL fragment

      • isQueryable

        boolean isQueryable()
        Not all functions will be queryable, or sensible to run queries against. These should return false.
        Returns:
        Whether the function is queryable.

      • buidQuerySQL

        java.lang.String buidQuerySQL​(DFTermExpression expr)
        Build the SQL fragment that defines the part of the WHERE clause. e.g. select ... from ... where ... and col1 + col2 < 100. If the function is not queryable this method can return null.
        Parameters:
        expr - The query expression e.g. field < 100
        Returns:
        The SQL fragment