Understanding SQL Server Case Sensitivity

Hello Dev,

SQL Server case sensitivity is a topic that can easily confuse anyone who is not familiar with it. In this article, we will explore the basics of case sensitivity in SQL Server and how it can affect your database performance and data integrity.

What is SQL Server Case Sensitivity?

Before we dive into the details of case sensitivity, it is important to understand what it means. Case sensitivity refers to the way that SQL Server treats letters in a query. If a query is case sensitive, it will treat uppercase and lowercase letters as distinct characters. This means that “Dev” and “dev” would not be considered the same.

On the other hand, if a query is not case sensitive, it will treat uppercase and lowercase letters as the same characters. This means that “Dev” and “dev” would be considered the same.

Default Case Sensitivity in SQL Server

SQL Server has a default case sensitivity setting that is used for all databases and tables unless otherwise specified. The default setting is not case sensitive, which means that uppercase and lowercase letters are treated as the same characters.

You can check the default case sensitivity setting for your server by running the following query:

Query
Result
SELECT DATABASEPROPERTYEX(‘master’, ‘Collation’);
SQL_Latin1_General_CP1_CI_AS

The result will show you the collation for your server, which includes the case sensitivity setting. In this example, the collation is “CI”, which stands for case-insensitive.

Changing the Case Sensitivity of a Database

If you want to change the case sensitivity setting for a specific database, you can do so by altering the database collation. However, this is not a simple task and should only be done by experienced database administrators.

Before you change the collation of a database, it is important to understand the potential impact on your data and applications. Changing the collation can cause issues with queries, indexes, and stored procedures that rely on specific collation settings.

If you are unsure about changing the collation of a database, it is best to consult with a professional DBA.

Case Sensitivity in Queries

When writing queries in SQL Server, it is important to understand how case sensitivity can affect your results. If your query is not case sensitive, you may inadvertently include duplicate data or miss important data.

For example, if you are searching for all names that contain “Dev”, a case-insensitive query would return both “Dev” and “dev”. However, a case-sensitive query would only return “Dev”.

To make your queries case sensitive, you can use the COLLATE keyword followed by a case sensitive collation. For example:

Query
Result
SELECT * FROM Customers WHERE Name COLLATE Latin1_General_CS_AS LIKE ‘%Dev%’;
Only returns customers with a name that contains “Dev” (not “dev”)

Case Sensitivity in Indexes

Indexes are a crucial part of SQL Server performance tuning, and case sensitivity can have a significant impact on their effectiveness. If your index is not case sensitive, it may include duplicate data or miss important data.

For example, if you have an index on the “Name” column and it is not case sensitive, it will include both “Dev” and “dev” as separate entries. This can significantly increase the size of your index and slow down query performance.

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To make your indexes case sensitive, you can specify a case sensitive collation when creating or altering the index. For example:

Query
Result
CREATE INDEX IX_Customers_Name ON Customers(Name COLLATE Latin1_General_CS_AS);
Creates a case sensitive index on the “Name” column

Case Sensitivity in Stored Procedures

If you use stored procedures in your SQL Server database, it is important to understand how case sensitivity can affect their behavior. If your stored procedure is not case sensitive, it may not return the expected results or may behave unpredictably.

For example, if you have a stored procedure that searches for a customer by name and it is not case sensitive, it may return multiple results for a search term like “Dev”.

To make your stored procedures case sensitive, you can use the COLLATE keyword followed by a case sensitive collation. For example:

Query
Result
CREATE PROCEDURE SearchCustomers @Name nvarchar(50) COLLATE Latin1_General_CS_AS ASSELECT * FROM Customers WHERE Name LIKE ‘%’ + @Name + ‘%’
Creates a case sensitive stored procedure for searching customers by name

FAQ

Q: What is the default case sensitivity setting for SQL Server?

A: The default case sensitivity setting for SQL Server is not case sensitive.

Q: Can I change the case sensitivity setting of a specific database?

A: Yes, you can change the case sensitivity setting of a specific database by altering the collation. However, this should only be done by experienced DBAs.

Q: How can I make my queries case sensitive?

A: You can make your queries case sensitive by using the COLLATE keyword with a case sensitive collation.

Q: How can I make my indexes case sensitive?

A: You can specify a case sensitive collation when creating or altering an index.

Q: How can I make my stored procedures case sensitive?

A: You can use the COLLATE keyword with a case sensitive collation when creating or altering a stored procedure.

Conclusion

Understanding SQL Server case sensitivity is crucial for maintaining data integrity and optimizing performance. By following the best practices outlined in this article, you can ensure that your database queries, indexes, and stored procedures function as expected.

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