Sql rank vs Dense_rank IN SQL SERVER

 Sql rank vs Dense_rank IN SQL SERVER

In SQL Server, `RANK()` and `DENSE_RANK()` are both window functions that are used to assign a rank to each row within a result set based on the values in one or more columns. However, they differ in how they handle duplicate values.

Here's a comparison of `RANK()` and `DENSE_RANK()` in SQL Server:

RANK():

- `RANK()` is a window function that assigns a unique rank to each distinct row within a result set based on the values in the specified column(s).

- If two or more rows have the same values, `RANK()` will assign the same rank to those rows and leave gaps in the ranking sequence for the next rank.

- The ranking values are not consecutive when there are ties.

**Example:**

```sql

SELECT 

    RANK() OVER (ORDER BY ColumnName) AS Rank

FROM 

    TableName;

# DENSE_RANK():

- `DENSE_RANK()` is also a window function that assigns a unique rank to each distinct row within a result set based on the values in the specified column(s).

- If two or more rows have the same values, `DENSE_RANK()` will assign the same rank to those rows but will not leave gaps in the ranking sequence.

 It produces consecutive ranking values, even when there are ties.

**Example:**

```sql

SELECT 

    DENSE_RANK() OVER (ORDER BY ColumnName) AS DenseRank

FROM 

    TableName;

In summary, if you want consecutive ranking values without any gaps, you should use `DENSE_RANK()`. If you don't mind having gaps in the ranking sequence for tied values, you can use `RANK()`. The choice between them depends on your specific use case and the behavior you want for tied values in your ranking results.