SQL SELECT TOP statement overview and examples

11 May SQL SELECT TOP statement overview and examples

But today, we’re focusing on the SELECT TOP clause as used in SQL Server. Let’s look at a SQL Server example, where we use the TOP PERCENT keyword in the SELECT statement. Let’s look at a SQL Server example, where basic database queries we use the TOP keyword in the SELECT statement. Let’s go ahead and explore the TOP clause and its performance aspects. Let’s look at a SQL example, where we use the TOP PERCENT keyword in the SELECT statement.

• Use the query below to insert the top 10 products with product prices in TopSalesPrice.
• This SQL Server tutorial explains how to use the SELECT TOP statement in SQL Server (Transact-SQL) with syntax and examples.
• The following query deletes a random row from the
  ProductListColors table.

Believe me, nothing beats the satisfaction of efficiently extracting exactly what you need. In this article, I’ll share insights and tips on how to wield SQL TOP like a pro. Let’s dive into making your data retrieval process as smooth as silk. Passing the list to this DELETE statement will delete the oldest 10 percent of
the records. Despite
that, TOP clauses get involved in the query plans of the queries.

SQL Database

In this article, we will learn how to use SQL SELECT TOP queries and we will also reinforce this learning using
examples.

TOP is usually used with the ORDER BY clause, as the
order of the data is not guaranteed unless specified. TOP and ORDER BY can be used
together to return the highest or lowest set of data, i.e., top x or top x percent
of best or worst selling items with the ASC or DESC parameter. The SELECT TOP clause is a powerful and flexible tool in SQL, offering a way to retrieve a specific number or percentage of records from a database. It’s essential when dealing with large datasets, allowing you to filter and return only the most relevant data. Because the order of rows stored in a table is unspecified, the SELECT TOP statement is always used in conjunction with the ORDER BY clause. Therefore, the result set is limited to the first N number of ordered rows.

How to use the GROUP BY clause on multiple columns in SQL?

By keeping these tips in mind and practicing with real queries, I’ve found that navigating the complexities of SQL data retrieval becomes far more manageable. Again, note how the ORDER BY clause ensures that we’re getting the latest products, not just any random selection. It’s a fantastic way to retrieve a slice of data based on proportion, rather than a fixed number. The following query deletes a random row from the
ProductListColors table. To handle such situations, you can use SQL’s TOP clause in your SELECT statement. However the TOP clause is only supported by the SQL Server and MS Access database systems.

When it comes to mastering the SQL TOP clause, there’s no substitute for diving right into some practical examples. Let’s break down a few scenarios where the TOP clause can be a game-changer in data retrieval tasks. Another typical oversight involves neglecting the ORDER BY clause, as mentioned earlier. Without specifying an order, the results can appear random, especially in a large dataset with continual updates. I’ve been down the rabbit hole of complex queries and massive datasets more times than I can count.

Demo Database

Additionally, I will explain the SQL Server TOP clause by applying it to the different tables to show you how it can be used. This SQL Server tutorial explains how to use the SELECT TOP statement in SQL Server (Transact-SQL) with syntax and examples. In the execution plan, we do not have a sort operator, and it uses a NonClustered scan along with clustered key lookup. The execution plan is the same; however, we see a warning in the sort operator. Sort operator also took 1.205s in comparison to 0.112s of the previous execution.

For this reason, it is the best practice to use the TOP clause with an ORDER
BY to obtain a certain sorted result. The following example uses PERCENT to specify the number of products returned in the result set. Whenever you run the query on a table to retrieve the records, it returns a result containing many records. It depends on your table size; sometimes, you need a certain number of rows in your result set.

Practical Examples of SQL TOP

To return only the highest 50 percent of pretax amounts is achieved by adding
a TOP 50 PERCENT to the SELECT statement. The following examples were run in SQL Server Management Studio (SSMS) 19.2 against
a copy of the

Wide World Importers sample database on a Microsoft SQL Server 2022 server. In MySQL, the LIMIT clause provides similar functionality, and in Oracle SQL, the ROWNUM clause serves the same purpose.

Understanding the nuances and applying these practices in real-world scenarios elevates the precision and performance of data retrieval in SQL. Practicing with these variations and avoiding common pitfalls is essential in mastering the SQL TOP clause. This query lacks clarity on what “top” means, rendering it essentially random.

In the event of a tie, additional records beyond the last record of that tie,
as specified in the ORDER BY clause, will be included in the result set. In the event of a tie, the result set will include additional records beyond
the last record of that tie, as specified in the ORDER BY clause. We’ve seen how the ORDER BY clause is used to sort records before limiting
what’s returned with the TOP clause. Now, we’ll look at using the GROUP
BY and HAVING clauses to group and filter the records returned.

Remember, the key to leveraging the TOP clause effectively lies in combining it with the ORDER BY statement to ensure you’re getting the most relevant data. Whether you’re working with SQL Server, MySQL, or PostgreSQL, the principles remain the same, though the syntax may vary. Dive into practicing with real-world examples and watch your database management skills soar. With these insights, I’m confident you’ll find using the SQL TOP clause to be a game-changer in your data retrieval tasks. ROW_NUMBER function helps to give temporary numbers to the result set of the query and it can be also used instead
of the TOP clauses. For example, the following query will return the first 4 rows of the Product table.

Here is a SQL query that pulls all rows from table VehicleTemperatures
ordered by RecordedWhen. If we want to delete the first row of the table according to a certain order, we can use CTE’s to perform this type of requirement. Through the
following query, we can delete a row that has the biggest ProductID. As has been pointed out in the above image, the query has returned an arithmetic overflow error. As we can see, the query has returned more than one product whose costs are the same as the first one. The SELECT TOP clause is used to specify the number of records to return.