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.
