Row Number in SQL | Most commonly asked interview question in SQL interviews
This article will describe the comprehensive guide on Row Number and by reading this article you will be able to know everything about Row Number in SQL.
What is the row number? what are all the prerequisites we need to work with a Row Number?
Row Number is a function which will help us to get the continuous ranking to the records without skipping any number in the results set whether it is partitioned or not.
It will help you to give a continuous number in the result set.
We need to know some other basic stuff in order to understand Row Number in SQL Queries.
- Row Number ()
- Order By ()
- Partition By ()
The Row Number we are going to call it as function, Order By and Partition By we are going to call it as a clause.
Means easily to identify, the function is going to end with parenthesis and Order By and Partition By is not going to end with Parenthesis.
Now let us come to the Order By Clause, This clause will decide how the ranking is going to start.
To generate a Row Number Partition is not mandatory but Order By is mandatory.
When we use a Partition what is happening?
This Partition clause is going to grouping the functionality based on some column.
See the below query how the Order By has generated a unique Row Number based on the customer name.
The output of the query gives you the below results.
Regardless of the duplicate Customer Name, the query has returned a Unique Order Number for each and every Customer transaction.
In Other Words, Row Number generates a Unique Number for each and every transaction done by the Customer regardless of the duplication.
You can read our article Top 6 SQL Queries and functions asked in interviews to know more about the Row Number Function.
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