# SQL Server beginner interview questions and answers

## Part - 1

Rajanand Ilangovan
·May 2, 2022·

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### How to generate a random string of 10 character?

There are many ways to generate a random string. This one is a simple way to do it.

``````SELECT RIGHT(CAST(NEWID() AS VARCHAR(255)),10)
``````

### How to generate a random number?

Generate a random number from 0 through 1, exclusive.

``````SELECT RAND()
``````

Generate a random number between 0 and 100.

``````SELECT FLOOR(RAND()*101)
SELECT CAST(RAND()*100 AS INT)
``````

Generate a random number between 1 and 100

``````SELECT CEILING(RAND()*100)
``````

Generate a random number between 10 and 30

``````SELECT 10 + FLOOR(RAND()*30)
``````

### COUNT(*) vs COUNT(1) vs SUM(1)

#### What is the output of the below queries when table is empty and non-empty?

``````SELECT COUNT(*) FROM STUDENT
SELECT COUNT(1) FROM STUDENT
SELECT SUM (1) FROM STUDENT
``````

When the table is empty:

When the table is non-empty:

### How to select all the even number records from a table?

There is a table `participant` which has more than 10k records and you need to select all the records with id in even number (i.e. 2,4,6,8 etc)

``````SELECT * FROM dbo.participant WHERE id % 2 = 0
``````

### How to select all the odd number records from a table?

There is a table `participant` which has more than 10k records and you need to select all the records with id in odd number (i.e. 1,3,5,7 etc)

``````SELECT * FROM dbo.participant WHERE id % 2 = 1
``````

### How to select all the records from the table except the id's which are divisible by 3?

There is a table `participant` which has more than 10k records and you need to select all the records from the table except id in 3,6,9, etc

``````SELECT * FROM dbo.participant WHERE id % 3 <> 0
``````