Original subtitles

0 Hi everyone 1

In this video 2

We'll learn about case expression 3

Case expression is a conditional expression 4

What is mean this if you want to specify several conditions on your data 5

While 6

Retrieving it or updating it 7

You can do it using the case expression 8

It is similar to mentioning the if else statements 9

While coding, so if you have done C , C++ or java 10

What you achieve by using if and else statements similar thing you can do using the case statement 11

The syntax of case statement is you write case 12

Then you mention when 13

Specify the first condition if it is true then 14

The result 15

You can again mention the second when, where you specify the second condition and if that is true 16

It will give the result 17

3rd, 4th and so on 18

And in the end you can specify else so if none of the condition specified above are true 19

The else will run 20

And whatever result you mentioned within this else clause 21

That will be executed 22

And to end the 23

Case expression we write end 24

There is another way to use case, you will write case and then mention an expression 25

This expression can be a column name 26

For each value in the column 27

This condition will be checked and wherever this condition is true 28

You will get the 29

Result corresponding to that condition 30

Let us look at 31

An example to understand it further 32

One of the major use cases of 33

Case statement is 34

When you want to assign categories to your data 35

So for example, in my customer data 36

If I want to categorise my 37

Customer data into 3 parts 38

Customers age Less than 30 will be categorised as young 39

Customers aged 30 to 60 will be called middle aged and customers 40

Beyond 60 years will be 41

Categorised as senior citizens 42

If I want to do this 43

I'll use case 44

I'll write select star so this will give me all the columns of the customer table 45

Comma 46

Case, so this will become a new column in after the entire table, so this column 47

Will be named case 48

And within this column, I want data 49

Such that 50

Customers who have age less 30 this column should contain young 51

Customers with age more than 60 this column should contain senior citizen 52

For all other customers 53

This column should contain middle aged 54

To finish this case statement 55

I'll write end 56

I can assign this whole column a name by using as age category 57

I do not write this 58

This column will be named as case 59

Now 60

Since I am using this alias this column will be named as age category 61

From 62

Customer table 63

Let us go and write this query in pg admin 64

We will select star 65

Comma case 66

When 67

Age is less than 30 68

Then output should be young 69

When age 70

Is more than 60 71

Then 72

Senior citizen 73

Else 74

Middle aged 75

End as 76

Age category 77

From 78

Customer 79

Let us run this 80

So if you scroll to the right 81

This new column will be 82

In the end 83

It is named as age category 84

And you can see 85

For customer with age 67, it has value senior citizen 86

For customer with age 33 it has 87

Value Middle aged 88

For customer with Value 20 89

It is young 90

This is how we use this conditional expression of case 91

That's all for this video, thanks