In SQL Server, the COUNT() function returns the number of items found in a group. You can use it to find out how many rows are in a table or result set.
Tag: mssql
How NTILE() Works in SQL Server
In SQL Server, the NTILE() function allows you to distribute the rows in an ordered partition into a specified number of groups. The groups are numbered, starting at 1. For each row, NTILE() returns the number of the group to which the row belongs.
You simply provide the number of groups you desire when calling the function.
How ROW_NUMBER() Works in SQL Server
In SQL Server, the ROW_NUMBER() function allows you to number the output of a result set. It returns the sequential number of each row, starting at 1.
If you specify partitions for the result set, each partition causes the numbering to start over again (i.e. the numbering will start at 1 for the first row in each partition).
How RANK() Works in SQL Server
In SQL Server, the RANK() function returns the rank of each row within the partition of a result set. The rank of a row is one plus the number of ranks that come before the row.
How DENSE_RANK() Works in SQL Server
In SQL Server, the DENSE_RANK() function returns the rank of each row within the partition of a result set. The rank of a row is one plus the number of distinct ranks that come before the row.
This function is similar to RANK(), but without the gaps in the ranking values that can occur with RANK() when ties exist in the result set.
How to Include Results that Tie for Last Place when Using the TOP Clause in SQL Server
When using the TOP clause in a query in SQL Server, you may encounter occasions where two or more results tie for last place. You probably wouldn’t even know when this happens, because the default behavior of TOP is to return no more than the number of rows you specify.
The TOP clause accepts a WITH TIES argument that allows you to specify whether or not to include all results that tie for last place. Rows can tie for last place due to their ORDER BY column containing the same value. Using this argument may therefore result in more rows being returned than you actually specified.
Pagination in SQL Server using OFFSET/FETCH
Pagination is often used in applications where the user can click Previous/Next to navigate the pages that make up the results, or click on a page number to go directly to a specific page.
When running queries in SQL Server, you can paginate the results by using the OFFSET and FETCH arguments of the ORDER BY clause. These arguments were introduced in SQL Server 2012, therefore you can use this technique if you have SQL Server 2012 or higher.
In this context, pagination is where you divide the query results into smaller chunks, each chunk continuing where the previous finished. For example, if a query returns 1000 rows, you could paginate them so that they’re returned in groups of 100. An application can pass the page number and page size to SQL Server, and SQL Server can then use it to return just the data for the requested page.
Return a Percentage of a Result Set in SQL Server
In SQL Server, you can use the TOP clause to limit the rows returned from a query to a certain percentage of the result set.
For example, you could return the top 10% of the results, or whatever percentage you need.
Limit the Rows Returned in a SQL Server Query by using the TOP Clause
In SQL Server, you can use the TOP clause to limit the rows returned from a query result set. This clause provides similar functionality to LIMIT in MySQL, and ROWNUM in Oracle, although there are differences in how each of these work.
Below are examples of using the TOP clause to limit the result set in SQL Server.
Return All Foreign Keys & CHECK Constraints in a SQL Server Database (T-SQL Examples)
In SQL Server, you can use Transact-SQL to return a list of all foreign keys and CHECK constraints for the current database.
The examples on this page query two system views in order to retrieve this information: sys.foreign_keys and sys.check_constraints. You can query each one separately, or use UNION to display them all in a single result set.