Conditional Statements in Tableau

Conditional Calculations:

We create calculations when If any calculation you want to use in the report
which is not there in database, then we create that calculation with right syntax at tableau level.

or
And we use the Calculations for customization purpose.

For An Example: Sales less than 10 K is  "Worst Sales", >10 K and < 15 K is
 "Average" , >15 K and < 20 K is "Above Average" , >20 K and < 50 K is
 "Meet Target" , >50 K and < 75 K is "Excellent Sales."

Tableau offering writing the conditions using the following approaches
1) IF
2) CASE

1) If condition with 1 Possible value  without Else part
IF [Condition Matches] then [Matched Value]  end

EX: If  sum([Sales])>15000 then "Good"  end

Description:
In the above example, If sales are more tan 15000 then those will be represented as "Good" (If condition matches then "Good" if Condition does not match then empty, i.e. null)
If Sales does not more then 15000 then those values are represented by empty since we did not define else part.
Next example will explains how out put will effect if we define else part.

2) If condition with 2 Possibilities including Else part

Syntax:

IF [Condition Matches] then [Matched Value] else [Non Matched Value]  end

EX: If  sum([Sales])>15000 then "Good" else "Average" end

Description: 
In the above example, If sales are more tan 15000 then those will be represented as "Good" (If condition matches then "Good" if Condition does not match then empty, i.e. null)
If Sales does not more then 15000 then those values are represented by  "Average" since we defined else part.

3) If then else - more than 2 Possibilities

if [Condition 1 Match] then [Value1]
elseif [Condition 2 Match] then [Value 2]
elseif [Condition 3 Match] then [Value 3]
elseif [Condition 4 Match] then [Value 4]
.....................
Else [Value N] end

EX:

If sum([Sales]) <15000 then "Below Average"
elseif  sum([Sales]) >=15000 and sum([Sales]) <25000 then "Average"
elseif  sum([Sales]) >=25000 and sum([Sales]) <50000 then "Above Average"
else "Excellent" end
=============================
Case <EXP>
when <Matches 1> then [Value 1]
when <Matches 2> then [Value 2]
when <Matches 3> then [Value 3]
Else [Value 4] end



Case [Region]
when "Central" then "Territory - 1"
when "East" then "Territory - 1"
else "Territory - 2" end

1) I want to Apply Different colours to the Regions as per Sales Value.
<10 K - Color 1
>=10 K And < 15 K then Color 2
>=15 K And < 25 K then Color 3
or Color 4

2) Difference between And , Or Operators in the Calculations.
Create few reports with BUZ Requirement.

3) I want to see 2013, 2014 data in 1 color, 2011, 2015 in another color.
(Don't use Editing Color Legend option for applying colors. Use Calculations to define colors)

4) Categorize the City's into different groups by using your own business situation.

5) I want apply Different shapes as per Sales Values.
Use Question -1 as situation & define the shapes.

Note:

As of now Tableau does not have "IN" operator in the Calculations to filter the multiple values but there is an alternative that is "OR"

Case [Region]
when "Central" then "Territory - 1"
when "East" then "Territory - 1"
else "Territory - 2" end

Or

If  [Region] = "Central" or   [Region] ="East" then "Territory - 1"
else "Territory - 2" end