


How Can I Use Special Characters Effectively in SQL LIKE Clauses for Pattern Matching?
Jan 07, 2025 am 07:25 AMComprehensive List of Special Characters for SQL LIKE Clause
In the context of SQL queries, the LIKE clause provides a powerful tool for performing pattern-based searches. To cater to a wide range of pattern matching requirements, various SQL dialects support a comprehensive set of special characters.
Common Special Characters
Across most SQL dialects, several common special characters are employed for pattern matching:
- % (Percent Sign): Represents any string of zero or more characters.
- _ (Underscore): Matches any single character.
- [] (Square Brackets): Encloses character ranges or specific characters for matching.
Database-Specific Variations
In addition to these common characters, certain databases offer additional capabilities:
SQL Server:
- **[specifier]: Matches a single character within the specified range (e.g., [a-z]).
- **[^specifier]: Matches a single character outside the specified range.
- ESCAPE clause: Allows specifying a character to escape the literal meaning of other special characters.
MySQL and Oracle:
- ESCAPE clause: Similar to SQL Server's ESCAPE clause.
PostgreSQL:
-
SIMILAR TO operator: Extends LIKE functionality with additional modifiers such as:
- []: As in SQL Server.
- |: Match either of two alternatives.
- *: Repeat the previous item zero or more times.
- : Repeat the previous item one or more times.
ANSI SQL92:**
- ESCAPE clause: Optional, if specified.
Example Usage
In SQL Server:
SELECT Name FROM Person WHERE Name LIKE '%Jon%'
finds all names containing "Jon" anywhere.
In PostgreSQL using the SIMILAR TO operator:
SELECT Name FROM Person WHERE Name SIMILAR TO 'J[ao]'
matches all names starting with either "Ja" or "Jo".
By leveraging the special characters supported by various SQL dialects, developers can construct highly flexible and efficient pattern matching queries.
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