SQL Operators

Understanding SQL Operators

Introduction:

SQL operators are essential components of the SQL language that allow you to perform various operations, comparisons, and manipulations on data in a relational database. They enable you to create complex queries, filter results, and perform calculations based on your specific requirements. In this article, we will explore the different types of SQL operators along with their usage and examples to help you master the art of SQL query construction effectively.

1. Arithmetic Operators:

Arithmetic operators in SQL are used to perform mathematical calculations on numeric data. Common arithmetic operators in SQL include:

• Addition (+): Adds two values
• Subtraction (-): Subtracts one value from another
• Multiplication (*): Multiplies two values
• Division (/): Divides one value by another

Example:

        SELECT column1 + column2 AS sum
        FROM table_name;
    

2. Comparison Operators:

Comparison operators in SQL are used to compare values and return a logical result (true or false). Common comparison operators in SQL include:

• Equal to (=): Checks if two values are equal
• Not equal to (!= or <>): Checks if two values are not equal
• Greater than (>): Checks if one value is greater than another
• Less than (<): Checks if one value is less than another
• Greater than or equal to (>=): Checks if one value is greater than or equal to another
• Less than or equal to (<=): Checks if one value is less than or equal to another

Example:

        SELECT *
        FROM table_name
        WHERE column1 > 10;
    

3. Logical Operators:

Logical operators in SQL are used to combine conditions and perform logical operations on multiple expressions. Common logical operators in SQL include:

• AND: Returns true if all conditions are true
• OR: Returns true if any of the conditions are true
• NOT: Negates a condition, i.e., returns true if the condition is false

Example:

        SELECT *
        FROM table_name
        WHERE condition1 AND (condition2 OR condition3);
    

4. String Operators:

String operators in SQL are used to manipulate and compare string values. Common string operators in SQL include:

• Concatenation (||): Concatenates two or more strings
• LIKE: Performs pattern matching on strings

Example:

        SELECT column1 || ' ' || column2 AS full_name
        FROM table_name
        WHERE column1 LIKE 'John%';
    

5. NULL-related Operators:

NULL-related operators in SQL are used to compare and check for NULL values. Common NULL-related operators in SQL include:

• IS NULL: Checks if a value is NULL
• IS NOT NULL: Checks if a value is not NULL

Example:

        SELECT *
        FROM table_name
        WHERE column1 IS NULL;