SQL Server: TOP…WITH TIES - A Beauty of TSQL

Introduction

The TOP clause is commonly used to get the top required rows from a result set. The beauty of this clause is that it can be used with the WITH TIES clause to retrieve all similar rows to a base result set.

Book Online

According to BOL “WITH TIES specifies that additional rows be returned from the base result set with the same value in the ORDER BY columns appearing as the last of the TOP n (PERCENT) rows. TOP...WITH TIES can be specified only in SELECT statements, and only if an ORDER BY clause is specified. “

Using the Code

For example, from the following simple table, I need to get records which have a minimum purchase date value. In the first method, we will use the common IN clause.

--Create temporary table
CREATE TABLE #MyTable (Purchase_Date DATETIME, Amount INT)
--Insert few rows to hold
INSERT INTO #MyTable
SELECT '11/11/2011', 100 UNION ALL
SELECT '11/12/2011', 110 UNION ALL
SELECT '11/13/2011', 120 UNION ALL
SELECT '11/14/2011', 130 UNION ALL
SELECT '11/11/2011', 150
--Get all records which has minimum purchase date (i.e. 11/11/2011)
SELECT * FROM #MyTable
WHERE Purchase_Date IN

       (SELECT MIN(Purchase_Date) FROM #MyTable)

We can also get our desired results by using TOP…WITH TIES.

SELECT TOP(1) WITH TIES * FROM #MyTable
ORDER BY Purchase_Date

Performance

By executing the above query, you can find TOP WITH TIES worked amazingly, but is this short code really smart code? Let’s compare their performances.

Though the TOP…WITH TIES clause really shortened our code, you can see that it performed poorly as compared to our traditional code. This happened just because of the ORDER BY clause. This poor performance can be controlled by placing a well defined index.