Efficiently Extracting Numbers from Strings in SQL Server

Learn how to efficiently extract numbers from strings in SQL Server using effective techniques and code examples for common patterns.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Extract number from certain strings in sql server

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Efficiently Extracting Numbers from Strings in SQL Server

Extracting specific values from strings is a common requirement in SQL server databases. Today, we'll focus on a practical example of extracting numbers that precede certain keywords from a string format. This guide will guide you through the problem and provide a robust solution to your number extraction needs using SQL Server.

The Problem

Let's consider the following input strings that include items with associated quantities:

[[See Video to Reveal this Text or Code Snippet]]

From these strings, we want to extract the numbers that appear directly before the keywords UN and UNITS. Our expected output would look like this:

[[See Video to Reveal this Text or Code Snippet]]

Previously, the query used to achieve this was complex, relying on nested functions and string manipulations. However, there's a simpler and more efficient method available.

The Solution

Using the PATINDEX function in conjunction with CROSS APPLY can simplify the extraction process. Let's break down the SQL code that effectively retrieves the needed values.

SQL Query Breakdown

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Query Components

CROSS APPLY: This allows us to join each row in MYTABLE with the results of a defined expression, making it easier for us to evaluate the position of each keyword in relation to the numbers.

PATINDEX: A function that returns the starting position of the first occurrence of a pattern in a string. In our case, we're looking for the positions of UN, UNITS, and the first number pattern [0-9] within the string.

CASE Statement: This checks which keyword is present (UN or UNITS) and then extracts the number accordingly using the SUBSTRING function.

Important Note

While using the desc keyword in SQL Server is possible, it’s advisable to avoid using reserved keywords as column names to prevent conflicts or confusion in your queries.

Conclusion

By using PATINDEX and CROSS APPLY, we’ve created a cleaner and more efficient way to extract required numbers from strings in SQL Server. This method not only simplifies the SQL code but also enhances its readability and maintainability.

If you frequently deal with string data in SQL, mastering techniques like this will help you manage and manipulate your data more effectively. Feel free to implement this solution in your own queries and enhance your SQL skills!