All language subtitles for 1. CASE WHEN

Hi everyone
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In this video
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We'll learn about case expression
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Case expression is a conditional expression
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What is mean this if you want to specify several conditions on your data
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While
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Retrieving it or updating it
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You can do it using the case expression
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It is similar to mentioning the if else statements
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While coding, so if you have done C , C++ or java
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What you achieve by using if and else statements similar thing you can do using the case statement
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The syntax of case statement is you write case
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Then you mention when
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Specify the first condition if it is true then
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The result
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You can again mention the second when, where you specify the second condition and if that is true
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It will give the result
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3rd, 4th and so on
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And in the end you can specify else so if none of the condition specified above are true
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The else will run
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And whatever result you mentioned within this else clause
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That will be executed
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And to end the
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Case expression we write end
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There is another way to use case, you will write case and then mention an expression
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This expression can be a column name
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For each value in the column
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This condition will be checked and wherever this condition is true
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You will get the
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Result corresponding to that condition
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Let us look at
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An example to understand it further
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One of the major use cases of
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Case statement is
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When you want to assign categories to your data
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So for example, in my customer data
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If I want to categorise my
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Customer data into 3 parts
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Customers age Less than 30 will be categorised as young
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Customers aged 30 to 60 will be called middle aged and customers
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Beyond 60 years will be
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Categorised as senior citizens
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If I want to do this
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I'll use case
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I'll write select star so this will give me all the columns of the customer table
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Comma
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Case, so this will become a new column in after the entire table, so this column
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Will be named case
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And within this column, I want data
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Such that
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Customers who have age less 30 this column should contain young
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Customers with age more than 60 this column should contain senior citizen
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For all other customers
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This column should contain middle aged
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To finish this case statement
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I'll write end
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I can assign this whole column a name by using as age category
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I do not write this
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This column will be named as case
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Now
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Since I am using this alias this column will be named as age category
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From
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Customer table
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Let us go and write this query in pg admin
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We will select star
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Comma case
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When
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Age is less than 30
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Then output should be young
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When age
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Is more than 60
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Then
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Senior citizen
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Else
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Middle aged
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End as
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Age category
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From
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Customer
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Let us run this
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So if you scroll to the right
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This new column will be
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In the end
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It is named as age category
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And you can see
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For customer with age 67, it has value senior citizen
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For customer with age 33 it has
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Value Middle aged
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For customer with Value 20
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It is young
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This is how we use this conditional expression of case
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That's all for this video, thanks