Dev’s Guide to SQL Server Instr

Welcome, Dev! In this article, we will be diving into SQL Server Instr function – its syntax, usage, and examples. This function is incredibly useful in finding specific strings within strings and we will explore its various applications. Let’s get started!

What is SQL Server Instr?

SQL Server Instr is a built-in string function that returns the starting position of a substring in a larger string. If the substring is not found, it returns 0. The syntax for the function is:

Function	Description
INSTR(string, substring)	Returns the starting position of the substring within the string

The parameters for the function are:

• string: The string to search within.
• substring: The substring to search for.

Using SQL Server Instr

Let’s take a look at an example of using SQL Server Instr. Say, we have the following table:

ID	Name	Email
1	John Doe	johndoe@example.com
2	Jane Doe	janedoe@gmail.com
3	Bob Smith	bobsmith@hotmail.com

If we wanted to find all the users with a Gmail address, we could use the following SQL statement:

SELECT NameFROM UsersWHERE INSTR(Email, 'gmail.com') > 0;

This would return:

Name
Jane Doe

SQL Server Instr FAQ

What is the difference between Instr and Charindex?

Both Instr and Charindex are used to find the position of a substring within a larger string. The difference lies in their syntax:

• SQL Server Instr: INSTR(string, substring)
• SQL Server Charindex: CHARINDEX(substring, string)

Notice that the order of the parameters is reversed. Instr returns 0 if the substring is not found, whereas Charindex returns null. Additionally, the two functions are not case-sensitive in their search.

Can Instr be used with wildcard characters?

Yes, Instr can be used with wildcard characters like % and _. For example:

SELECT NameFROM UsersWHERE INSTR(Email, '%@gmail.com') > 0;

This would return all the users with a Gmail address.

Can I use Instr in a JOIN statement?

Yes, you can use Instr in a JOIN statement. For example:

SELECT U.Name, O.OrderNumberFROM Users UJOIN Orders O ON INSTR(O.Notes, U.Name) > 0;

This would return all the orders that contain the name of the user who placed the order.

Can Instr be used with non-ASCII characters?

Yes, Instr can be used with non-ASCII characters. However, there are some caveats to keep in mind. Firstly, the collation of the database must support the characters being searched for. Secondly, the Unicode version of the function must be used (i.e., NCHARINDEX instead of INSTR).

Can I use Instr to remove a substring from a larger string?

Yes, you can use Instr to remove a substring from a larger string. Here’s one way to do it:

DECLARE @string VARCHAR(50) = 'Hello, world!'DECLARE @substring VARCHAR(10) = ', world'DECLARE @position INT = INSTR(@string, @substring)SELECT SUBSTRING(@string, 1, @position - 1) + SUBSTRING(@string, @position + LEN(@substring), LEN(@string) - @position) AS 'Result';

This would return “Hello!”

Conclusion

We’ve covered the basics of SQL Server Instr function, including its syntax, usage, and examples. We even explored some frequently asked questions to help you get started with using this function. We hope you found this article useful and informative!