Working with large datasets often involves searching for patterns buried deep in your data. Whether you’re validating entries, cleaning records, or identifying errors, pinpointing specific text within strings, these tasks can quickly become overwhelming without the right tools. That’s where the PATINDEX() function in SQL Server comes in, offering a powerful solution for locating patterns quickly and accurately.
PATINDEX() enables you to perform precise, pattern-based searches across your data. By identifying specific text or sequences within larger strings, this function simplifies tasks like data cleansing, validation, and troubleshooting. Its ability to handle patterns using wildcards makes it incredibly versatile, whether you’re isol ating anomalies, extracting useful data, or ensuring compliance with data rules.
Instead of relying on manual checks or overly complex logic, PATINDEX delivers fast, reliable results. It’s designed for real-world challenges, such as finding inconsistencies in records or pinpointing where a certain pattern appears across millions of rows.
This guide will show you how to use PATINDEX effectively, providing examples and insights to help you incorporate it into your workflow. If you’ve been looking for a way to simplify data searches in SQL Server, you’re about to discover a game-changer. Let’s dive in.
Table of contents
- What is the SQL Server PATINDEX() function?
- Parameters of PATINDEX()
- Try it yourself with dbForge Studio for SQL Server
- Step-by-step guide: Running PATINDEX() queries in dbForge Studio for SQL Server
- Advanced uses of PATINDEX() with wildcards
- Combining PATINDEX() with other SQL Server functions
- Conclusion
What is the SQL Server PATINDEX() function?
The PATINDEX() function is a powerful tool in SQL Server that allows you to search for patterns within strings. It scans the given expression for a specific pattern and returns the starting position of the first occurrence. If no match is found, it returns 0, making it easy to validate whether a pattern exists in your data.
While PATINDEX shares some similarities with other SQL Server functions like CHARINDEX, it sets itself apart by supporting wildcards. This makes PATINDEX a more versatile choice for complex pattern searches where flexible matching is required.
Syntax explanation
The basic syntax for PATINDEX is:
PATINDEX('%pattern%', expression) Here’s a breakdown of its components:
| Component | Description |
|---|---|
| %pattern% | Defines the search criteria using wildcards: – %: Matches any string of any length (including zero length). – %: Matches any string of any length (including zero length). – _: Matches exactly one character. – [ ]: Matches any character enclosed within the brackets (e.g., [a-z] matches any lowercase letter). – [^ ]: Matches any character not enclosed within the brackets (e.g., [^0-9] matches any non-numeric character). |
| expression | The source string or column in which the pattern is being searched. This can be: – A literal string, such as ‘SQL Server’. – A column from a table, such as CustomerName in a SELECT statement. |
%pattern%:
Defines the search criteria using wildcards:
- % matches any string of any length (including zero length).
- _ matches exactly one character.
- [ ] matches any character enclosed within the brackets (e.g., [a-z]).
- [^ ] matches any character not enclosed within the brackets (e.g., [^0-9] matches any non-numeric character).
Expression:
The source string or column in which the pattern is being searched. This can be a literal string or a column from a table.
How PATINDEX differs from CHARINDEX
While both PATINDEX and CHARINDEX are used to locate substrings in a string, PATINDEX is more flexible:
- PATINDEX allows the use of wildcards for pattern-based searches.
- CHARINDEX only finds exact matches of a substring.
For instance, if you’re searching for a numeric character in a string, PATINDEX can match any digit using [0-9], while CHARINDEX would require the exact number to be specified.
Example
Let’s see PATINDEX in action with a simple example:
Query:
SELECT PATINDEX(‘%SQL%’, ‘Welcome to SQL Server’) AS PatternPosition;
Explanation:
- %SQL% looks for the substring SQL anywhere in the string.
- If found, PATINDEX returns the position of the first match.
Result:
PatternPosition
----------------
12 This means the substring “SQL” starts at the 12th character in the string “Welcome to SQL Server.”
Example with wildcards
Let’s take it a step further using wildcards:
SELECT PATINDEX('%[0-9]%', 'Error Code: 404') AS FirstNumericPosition; Explanation:
- %[0-9]% looks for any numeric character (0 through 9) in the string.
- PATINDEX returns the position of the first digit.
Result:
FirstNumericPosition
---------------------
13 In this case, PATINDEX identifies that the first numeric character, “4,” appears at position 13.
By understanding how PATINDEX works and utilizing its flexibility, you can efficiently locate patterns in your data and simplify even the most complex search tasks. Let’s move on to explore the parameters in greater detail.
Parameters of PATINDEX()
The effectiveness of PATINDEX() lies in its ability to leverage flexible parameters, enabling precise and dynamic searches. Here’s a detailed explanation of its two key parameters and how they can be applied in real-world scenarios.
%pattern%: Defining search criteria
The %pattern% parameter allows you to define the search pattern using wildcards. This flexibility makes PATINDEX an ideal choice for locating complex or variable patterns in strings.
| Wildcard | Description |
|---|---|
| % | Matches any string of any length, including an empty string. |
| _ | Matches exactly one character, regardless of what it is. |
| [ ] | Matches any single character within the specified range or set (e.g., [a-z], [0-9]). |
| [^ ] | Matches any single character not in the specified range or set (e.g., [^a-z]). |
Examples of wildcards in action
1. Searching for alphanumeric characters
SELECT PATINDEX('%[A-Za-z0-9]%', 'SQL123 Query') AS PositionOfFirstAlphanumeric; Explanation:
- %[A-Za-z0-9]% matches any alphanumeric character.
- In “SQL123 Query,” the first match is “S” at position 1.
Result:
PositionOfFirstAlphanumeric
---------------------------
1 2. Identifying specific character ranges
SELECT PATINDEX('%[a-m]%', 'Welcome to SQL Server') AS FirstMatchInRange; Explanation:
- %[a-m]% matches any lowercase letter between “a” and “m.”
- In “Welcome to SQL Server,” “e” is the first match, at position 2.
Result:
FirstMatchInRange
------------------
2 Expression: The source of the search
The expression parameter defines where the pattern will be searched. It can be:
- A literal string: Useful for quick tests or static values.
- A column value: Perfect for searching within dynamic data in SQL Server tables.
Practical column-based search example
Imagine a table named Employees with a column Email. You can use PATINDEX to locate specific patterns in email addresses:
DECLARE @Employees TABLE (Email VARCHAR(255));
INSERT INTO @Employees (Email)
VALUES
('[email protected]'),
('[email protected]'),
('[email protected]');
SELECT Email, PATINDEX('%@%', Email) AS AtSymbolPosition
FROM @Employees;
https://prnt.sc/hnetSFnMfsdE Explanation:
- PATINDEX(‘%@%’, Email): Searches for the @ symbol anywhere in the string.
- Returns the position of the first occurrence of @ in each row.
- If @ is not found, PATINDEX() returns 0 (unlike CHARINDEX(), which returns 0 only in some cases).
Result (Example Data):
| AtSymbolPosition | |
|---|---|
| [email protected] | 9 |
| [email protected] | 11 |
| [email protected] | 10 |
Visual example: Patterns in action
To demonstrate how patterns influence search results, here’s a tabular breakdown:
| Pattern | Expression | Result Position | Explanation |
|---|---|---|---|
| %SQL% | Welcome to SQL Server | 12 | Matches “SQL” anywhere in the string. |
| %[0-9]% | Error Code: 404 | 13 | Matches the first digit in the string. |
| %@% | [email protected] | 9 | Matches the “@” symbol in an email. |
| %[^a-zA-Z]% | User#123 | 5 | Matches the first non-alphabetic character (“#”). |
Once you know how to use %pattern% and expression effectively, PATINDEX becomes a powerful tool for solving a wide range of search challenges. Let’s look at some practical examples to see how it works in action.
Examples of using PATINDEX() in SQL Server
The PATINDEX() function provides a versatile way to locate patterns within strings, making it an essential tool for text parsing, validation, and manipulation. Let’s look at some practical examples of how you can use PATINDEX() in SQL Server.
Simple Query examples
Example 1: Locating the position of a substring
SELECT PATINDEX('%SQL%', 'Welcome to SQL Server') AS Position; Explanation:
- The %SQL% pattern checks for the presence of the substring “SQL” anywhere in the string “Welcome to SQL Server.”
- PATINDEX returns the starting position of the first occurrence of this substring.
Result:
Position
--------
12 This example demonstrates how PATINDEX can quickly find the location of a specific substring, making it a time-saver for tasks like searching for keywords or identifying specific data points.
Real-world use case
Example: Finding the first vowel in a string
Suppose you need to identify the first vowel in a string for data validation or text manipulation purposes. PATINDEX makes this process straightforward:
SELECT PATINDEX('%[aeiou]%', 'dbForge') AS FirstVowelPosition; Explanation:
- The %[aeiou]% pattern searches for the first occurrence of any vowel (a, e, i, o, u) in the string “dbForge.”
- PATINDEX returns the starting position of the first vowel in the string.
Result:
FirstVowelPosition
-------------------
3 This is particularly useful for extracting or processing text based on vowels, such as generating derived values or analyzing language-specific patterns.
Behavior of PATINDEX() with no matches
When PATINDEX doesn’t find a match for the specified pattern, it returns 0. This predictable behavior allows for robust error handling in your queries.
Example: No pattern found
SELECT PATINDEX('%[xyz]%', 'dbForge') AS NoMatchResult; Explanation:
- The %[xyz]% pattern searches for the characters “x,” “y,” or “z” in the string “dbForge.”
- Since none of these characters exist in the string, PATINDEX returns 0.
Result:
NoMatchResult
--------------
0 This feature ensures that your queries can handle edge cases without breaking or throwing errors, making PATINDEX an excellent choice for flexible string searches.
Example: Query execution
To make these examples more relatable, here’s how the results appear when executed in dbForge Studio for SQL Server or SSMS:
Example query and results:
| Query | Input String | Pattern | Result | Explanation |
|---|---|---|---|---|
| PATINDEX(‘%SQL%’, ‘Welcome to SQL Server’) | Welcome to SQL Server | %SQL% | 12 | “SQL” starts at position 12. |
| PATINDEX(‘%[aeiou]%’, ‘dbForge’) | dbForge | %[aeiou]% | 3 | The first vowel, “o,” is at position 3. |
| PATINDEX(‘%[xyz]%’, ‘dbForge’) | dbForge | %[xyz]% | 0 | No match for “x,” “y,” or “z.” |
Next, we’ll explore how PATINDEX can work alongside dbForge Studio for SQL Server to make writing and testing these queries even simpler.
Try it yourself with dbForge Studio for SQL Server
dbForge Studio for SQL Server simplifies working with SQL Server, offering a clean, intuitive interface for crafting and testing PATINDEX() queries. No matter your level of experience, this tool helps you get the most out of SQL’s pattern-matching capabilities.
Why use dbForge Studio for SQL Server ?
Simplified pattern-based searches
Visual Query Builder in dbForge Studio for SQL Server allows you to create and execute PATINDEX() queries without having to write SQL manually. This feature makes it accessible even for users with limited SQL experience.
Enhanced debugging tools
Unlike SSMS, dbForge Studio for SQL Server provides:
- Advanced result grids for clear and structured output.
- Query execution plans to optimize performance.
- Built-in code completion to minimize syntax errors and speed up query writing.
User-friendly interface
dbForge Studio for SQL Server ’s modern design includes tabs, panels, and customizable layouts that make managing multiple queries and datasets seamless.
Step-by-step guide: Running PATINDEX() queries in dbForge Studio for SQL Server
Step 1: Write your query
Open dbForge Studio for SQL Server and navigate to the query editor. Enter a PATINDEX() query, such as:
SELECT PATINDEX('%SQL%', 'Welcome to SQL Server') AS Position; 
Step 2: Execute the query
Click the Execute button or press F5 to run the query.
Step 3: View the results
Check the output in the Results Grid. For the query above, you’ll see:
Position
--------
12 
Step 4: Experiment with variations
Try modifying the pattern or the source string to explore how PATINDEX behaves. For example:
SELECT PATINDEX('%[aeiou]%', 'dbForge') AS FirstVowelPosition; 
Resources for getting started
- Download dbForge Studio for SQL Server : Install the software and explore its features with a free trial.
- Installation Guide: Step-by-step instructions to set up dbForge Studio for SQL Server.
- Devart Academy: Watch a video walkthrough to get started with dbForge Studio for SQL Server.
With dbForge Studio for SQL Server, pattern-based queries like PATINDEX() are faster and easier to test. The tool doesn’t just simplify query creation—it enhances your productivity, giving you more time to focus on insights rather than troubleshooting syntax.
Advanced uses of PATINDEX() with wildcards
PATINDEX() becomes a truly powerful tool when used with wildcards and combined with other SQL Server functions. These advanced techniques allow you to pinpoint patterns, manipulate string data dynamically, and solve otherwise complex challenges in a straightforward way. Let’s explore some practical examples.
Using PATINDEX() with character ranges
Wildcards are the backbone of PATINDEX(). They let you specify flexible patterns for more targeted searches. For instance, you can locate non-alphanumeric characters, detect specific ranges, or find excluded values.
Example: Locating non-alphanumeric characters
This query identifies the position of the first character in a string that is not a letter or number:
SELECT PATINDEX('%[^a-zA-Z0-9]%', 'Hello@World') AS NonAlphaNumericPosition; Explanation:
- %[^a-zA-Z0-9]%: This pattern matches any character that is not a letter (a-z, A-Z) or a number (0-9).
- ‘Hello@World’: The input string where the pattern is being searched.
Output: The position of the first non-alphanumeric character, @, which is at position 6.
Result:
NonAlphaNumericPosition
-----------------------
6 Combining PATINDEX() with LEN and REVERSE
Sometimes, your search needs go beyond the first occurrence of a pattern. By pairing PATINDEX() with functions like LEN() and REVERSE(), you can find patterns from the end of a string or handle more dynamic queries.
Example: Finding the last vowel in a string
This query determines the position of the last vowel in the string ‘dbForge’:
SELECT LEN('dbForge') - PATINDEX('%[aeiou]%', REVERSE('dbForge')) + 1 AS LastVowelPosition; Explanation:
- REVERSE(‘dbForge’): Reverses the string to ‘egroFbd’.
- PATINDEX(‘%[aeiou]%’, REVERSE(‘dbForge’)): Finds the first vowel (‘e’) in the reversed string, which is at position 1.
- LEN(‘dbForge’): Calculates the length of the original string (7).
- LEN – PATINDEX + 1: Converts the position from the reversed string back to the original string, resulting in position 7.
Result:
LastVowelPosition
------------------
7 Example
1. Wildcard impact table
| Pattern | Matches | Example Input | Position Found |
|---|---|---|---|
| %[aeiou]% | Any vowel | ‘dbForge’ | 2 |
| %[^a-zA-Z0-9]% | Any non-alphanumeric character | ‘Hello@World’ | 6 |
| %[0-9]% | Any digit | ‘SQL123’ | 4 |
By combining wildcards, character ranges, and functions like LEN() and REVERSE(), PATINDEX transforms into a versatile tool for handling intricate pattern searches. From cleaning messy data to solving advanced text challenges, it offers precision and control.
Combining PATINDEX() with other SQL Server functions
PATINDEX becomes even more versatile when paired with other SQL Server functions like SUBSTRING and CHARINDEX. By combining these functions, you can solve a variety of text manipulation challenges, from extracting usernames to identifying invalid data entries. Let’s dive into some practical examples.
PATINDEX + SUBSTRING for pattern extraction
Combining PATINDEX with SUBSTRING allows you to extract parts of a string based on patterns. A common use case is extracting usernames from email addresses.
Example: Extracting usernames from email addresses
Here’s how to use PATINDEX to find the position of the @ symbol and SUBSTRING to extract the username:
DECLARE @Users TABLE (Email VARCHAR(255));
INSERT INTO @Users (Email)
VALUES
('[email protected]'),
('[email protected]');
SELECT Email, SUBSTRING(Email, 1, PATINDEX('%@%', Email) - 1) AS Username
FROM @Users; Explanation:
- PATINDEX(‘%@%’, Email): Searches for the first occurrence of @ in the email string. Unlike CHARINDEX(), PATINDEX() allows pattern-based searches using wildcards.
- PATINDEX(‘%@%’, Email) – 1: Determines the length of the username by subtracting 1 from the @ position.
- SUBSTRING(Email, 1, PATINDEX(‘%@%’, Email) – 1): Extracts characters before the @ symbol.
- CASE statement: Ensures that if the @ symbol is missing, the query returns NULL instead of causing an error.
Result example:
| Username | |
|---|---|
| [email protected] | john.doe |
| [email protected] | mary_smith |
PATINDEX + CHARINDEX for advanced manipulations
Pairing PATINDEX with CHARINDEX provides additional flexibility when you need to locate and manipulate specific segments of text. This is particularly useful for more complex queries where precise positioning matters.
Example: Extracting domains from email addresses
This query extracts the domain from an email address:
DECLARE @Users TABLE (Email VARCHAR(255));
INSERT INTO @Users (Email)
VALUES
('[email protected]'),
('[email protected]');
SELECT Email, SUBSTRING(Email, CHARINDEX('@', Email) + 1, LEN(Email) - CHARINDEX('@', Email)) AS Domain
FROM @Users; Explanation:
- CHARINDEX(‘@’, Email): Finds the position of the @ symbol in the email string.
- CHARINDEX(‘@’, Email) + 1: Moves the start position to the first character after @.
- LEN(Email) – CHARINDEX(‘@’, Email): Calculates the correct length to extract the domain part.
Result Example:
| Domain | |
|---|---|
| [email protected] | gmail.com |
| [email protected] | yahoo.com |
Real-world scenarios
1. Identifying invalid characters in datasets
You can use PATINDEX to locate unwanted characters in a dataset, such as special symbols or white spaces.
DECLARE @Users TABLE (Email VARCHAR(255));
INSERT INTO @Users (Email)
VALUES
('invalid-email/.com');
SELECT Email, PATINDEX('%[^a-zA-Z0-9@._-]%', Email) AS InvalidCharPosition
FROM @Users
WHERE PATINDEX('%[^a-zA-Z0-9@._-]%', Email) > 0; Explanation:
PATINDEX(‘%[^a-zA-Z0-9@._-]%’, Email):
- Searches for the first occurrence of an invalid character (i.e., any character not in the allowed set [a-zA-Z0-9@._-]).
- The ^ inside the brackets ([^…]) means “not in this set.”
WHERE PATINDEX(…) > 0:
- Ensures the query returns only rows that contain invalid characters, filtering out valid email addresses.
2. Extracting file extensions from file names
DECLARE @Documents TABLE (FileName VARCHAR(255));
INSERT INTO @Documents (FileName)
VALUES
('report.pdf'),
('presentation.pptx');
SELECT FileName, SUBSTRING(FileName, CHARINDEX('.', FileName) + 1, LEN(FileName)) AS FileExtension
FROM @Documents; Explanation:
- REVERSE(FileName): Flips the string so the last . becomes the first occurrence in the reversed string.
- CHARINDEX(‘.’, REVERSE(FileName)): Finds the first occurrence of . in the reversed string (which is actually the last . in the original string).
- RIGHT(FileName, CHARINDEX(‘.’, REVERSE(FileName)) – 1): Extracts everything after the last “.”
Result example:
| FileName | FileExtension |
|---|---|
| report.pdf | |
| presentation.pptx | pptx |
Using PATINDEX with SUBSTRING and CHARINDEX gives you the tools to quickly extract or clean up text in your data. These combinations are perfect for solving real-world problems like finding domains or validating strings.
Further learning
Mastering functions like PATINDEX is a fantastic step toward becoming a more efficient SQL Server user. But why stop here? There’s always more to explore and refine in your SQL journey. To help you expand your skills and dive deeper into the world of SQL Server, here are some handpicked resources and opportunities to learn more.
Additional resources
- SQL server tutorials: A comprehensive library of tutorials that covers everything from basic SQL concepts to advanced techniques.
- dbForge Studio for SQL Server documentation: Step-by-step guides on how to make the most of dbForge Studio for SQL Server , including advanced query-building tips.
- Devart Academy: Online courses designed to help you enhance your database management skills and stay ahead in the field.
- dbForge Studio for SQL Server video tutorials: Watch detailed walkthroughs and see tools like PATINDEX in action, all within the dbForge Studio for SQL Server environment.
The takeaway
Now that you’ve explored how PATINDEX works and seen its real-world applications, it’s time to put this knowledge into practice. Use the examples provided, test your queries with tools like dbForge Studio for SQL Server, and integrate PATINDEX into your data workflows to make them more efficient and reliable.
The possibilities with PATINDEX don’t stop here. Continue learning by exploring related SQL Server functions like SUBSTRING() and CHARINDEX(), and unlock even more potential for working smarter with your data.
