SQL Basics
SQL Case Sensitivity
Case Sensitivity in SQL
SQL case sensitivity affects identifiers, with quoted identifiers enforcing exact matches.
Introduction to SQL Case Sensitivity
In SQL, case sensitivity can affect how identifiers such as table names, column names, and aliases are interpreted by the database. Understanding these differences is crucial for writing accurate SQL queries and avoiding potential errors.
Case Sensitivity in SQL Identifiers
By default, SQL treats identifiers in a case-insensitive manner. This means that the database does not distinguish between uppercase and lowercase letters in identifiers, unless they are quoted. For example, SELECT, Select, and select are considered equivalent.
All the above queries will work similarly in most SQL databases because they treat identifiers case-insensitively by default.
Using Quoted Identifiers
Quoted identifiers, enclosed in double quotes (") or square brackets ([]), are treated as case-sensitive. This means the exact case must match the case used during creation.
For instance, if you create a table with a quoted identifier:
Querying it requires using the exact case:
Attempting to query the table with a different case will result in an error:
Best Practices for Using Identifiers
To avoid issues related to case sensitivity, consider adopting the following best practices:
- Stick to a consistent naming convention for all identifiers. Using all lowercase or all uppercase can prevent confusion.
- Avoid using quoted identifiers unless necessary, as they introduce case sensitivity which can lead to errors if not consistently handled.
- Check your database documentation as some databases may have different defaults for case sensitivity.
Conclusion
Understanding SQL's approach to case sensitivity will help you write more robust and error-free queries. By following best practices and being aware of how your specific SQL database handles case sensitivity, you can avoid common pitfalls and ensure the accuracy of your SQL operations.
SQL Basics
- Introduction
- Syntax
- Data Types
- SELECT
- WHERE
- ORDER BY
- DISTINCT
- LIKE
- IN
- BETWEEN
- NULL Handling
- LIMIT and OFFSET
- Aliases
- Comments
- Case Sensitivity
- Operators
