Logical Functions
This article introduces logical functions and their uses in Tableau. It also demonstrates how to create a logical calculation using an example.
Why use logical calculations
Logical calculations allow you to determine if a certain condition is true or false (boolean logic). For example, you might want to quickly see if sales for each country you distribute your merchandise to were above or below a certain threshold.
The logical calculation might look something like this:
SUM(Sales) > 1,000,000
Logical functions available in Tableau:
Function 
Syntax 
Description 
AND 
IF <expr1> AND <expr2> THEN <then> END

Performs a logical conjunction on two expressions. Example:

CASE 
CASE <expression> WHEN <value1> THEN <return1> WHEN
<value2> THEN <return2> ... ELSE <default return> END

Performs logical tests and returns
appropriate values. The CASE function evaluates CASE is often easier to use than IIF or IF THEN ELSE. Typically, you use an IF function to perform a sequence of arbitrary tests, and you use a CASE function to search for a match to an expression. But a CASE function can always be rewritten as an IF function , although the CASE function will generally be more concise. Many times you can use a group to get the same results as a complicated case function. Examples:

ELSE 
IF <expr> THEN <then> ELSE <else> END

Tests a series of expressions returning the <then> value for the first true <expr>. Example:

ELSEIF 
IF <expr> THEN <then> [ELSEIF <expr2> THEN <then2>...] [ELSE <else>] END

Tests a series of expressions returning the <then> value for the first true <expr>. Example:

END 
IF <expr> THEN <then> [ELSEIF <expr2> THEN <then2>...] [ELSE <else>] END

Tests a series of expressions returning the <then> value for the first true <expr>. Must be placed at the end of an expression. Example:

IF 
IF <expr> THEN <then> [ELSEIF <expr2> THEN <then2>...] [ELSE <else>] END

Tests a series of expressions returning the <then> value for the first true <expr>. Example:

IFNULL 
IFNULL(expr1, expr2)

Returns <expr1> if it is not null, otherwise returns <expr2>. Example:

IIF 
IIF(test, then, else, [unknown])

Checks whether a condition is met, and returns one value if TRUE, another value if FALSE, and an optional third value or NULL if unknown. Example:

ISDATE 
ISDATE(string)

Returns true if a given string is a valid date. Example:

ISNULL 
ISNULL(expression)

Returns true if the expression does not contain valid data (Null). Example:

MAX 
MAX(expression) or Max(expr1, expr2) 
Returns the maximum of a single expression across all records or the maximum of two expressions for each record. Example:

MIN 
MIN(expression) or MIN(expr1, expr2) 
Returns the minimum of an expression across all records or the minimum of two expressions for each record. Example:

NOT 
IF NOT <expr> THEN <then> END

Performs logical negation on an expression. Example:

OR 
IF <expr1> OR <expr2> THEN <then> END

Performs a logical disjunction on two expressions. Example:

THEN 
IF <expre> THEN <then> [ELSEIF ,expr2> THEN <then2>...] [ELSE <else>] END

Tests a series of expressions returning the <then> value for the first true <expr>. Example:

WHEN 
CASE <expr> WHEN <Value1> THEN <return1> ... [ELSE <else>] END

Finds the first <value> that matches <expr> and returns the corresponding <return>. Example:

ZN 
ZN(expression)

Returns <expression> if it is not null, otherwise returns zero. Example:

Create a logical calculation
Follow along with the steps below to learn how to create a logical calculation.

In Tableau Desktop, connect to the Sample  Superstore saved data source, which comes with Tableau.

Navigate to a worksheet.

From the Data pane, drag State to the Rows shelf.

From the Data pane, drag Category to the Rows shelf and place it to the right of State.

From the Data pane, drag Sales to the Columns shelf.

Select Analysis > Create Calculated Field.

In the calculation editor that opens, do the following:

Name the calculated field, KPI.

Enter the following formula:
SUM([Profit]) > 0
This calculation quickly checks if a member is great than zero. If so, it returns true; if not, it returns false.

When finished, click OK.
The new calculated field appears under Measures in the Data pane. Just like your other fields, you can use it in onr or more visualizations.

From the Data pane, drag KPI to Color on the Marks card.
You can now see which categories are losing money in each state.
See Also
Visualize Key Progress Indicators
Logic Calculations free video tutorial