Word of caution
Although some of the functions supported in Tableau have the same name as the functions you use in other applications or languages (SQL, for example), I caution you against assuming that it works the same way. There are functions that have the same name but will require different arguments, or return a different type, or both.
One example is the ISNULL function. In Tableau, the syntax of ISNULL is as follows:
ISNULL(expression)
This function in Tableau accepts a single argument and returns a Boolean value.
Transact-SQL (or T-SQL) has a similar function. However, the syntax in T-SQL is as follows:
ISNULL(check_expression, replacement_value)
In T-SQL, this function accepts two arguments and replaces the expression value if it is null. The return type is not a Boolean value. The function returns the same return type as the check_expression argument.
Support for regular expressions was introduced in Tableau V9. Regular expressions allow searching through patterns. This is quite powerful...
