Understanding the LIKE Keyword in SQL

Introduction

In this presentation, we delve into the use of the LIKE keyword in SQL.

Importance of LIKE Keyword

• Primarily used with the SELECT statement.
• Enhances the functionality of the WHERE clause.
• Facilitates pattern matching in columns.

Basic Concept

• The WHERE clause filters records based on conditions.
• The LIKE keyword searches for specific patterns within a column.

Wildcards

• Percentage (%): Represents zero or more characters.
• Underscore (_): Represents a single character.

Syntax

SELECT column1, column2, ..., columnN 
FROM table_name 
WHERE column LIKE some_pattern;

Examples

1. Search Pattern: A%

   SELECT * FROM student WHERE name LIKE 'A%';
   

   • Retrieves records with names starting with "A".

2. Ending Pattern: %A

   SELECT * FROM employee WHERE city LIKE '%I';
   

   • Retrieves city names ending with "I".

3. Containing Pattern: %OR%

   SELECT * FROM employee WHERE city LIKE '%OR%';
   

   • Retrieves city names containing the substring "OR".

4. Special Position Pattern: _C%

   • Retrieves values where "C" is the second character.

Example Queries

• Starts and Ends with specific characters

  SELECT * FROM employee WHERE city LIKE 'A%D';
  

  • Finds city names starting with "A" and ending with "D".

Homework

• Apply patterns on the name column:
  • Starts with "A", ends with "A", etc.
  • Example: 'A%', '%A', etc.

Summary

• The LIKE keyword is crucial for filtering based on character patterns.
• Wildcards % and _ offer flexible options for search queries.

Conclusion

This session provides an understanding of using the LIKE keyword effectively with examples for practical application. Thank you for engaging with the material.