SQL Operators

 SQL operators are symbols or keywords used to perform operations on data in SQL queries. They are essential for filtering, sorting, or manipulating data within the database. Here's a breakdown of the main SQL operators:

1. Arithmetic Operators

These operators perform mathematical operations on numeric values.

• + (Addition)
• - (Subtraction)
• * (Multiplication)
• / (Division)
• % (Modulo or Remainder)

Example:

SELECT salary + 1000 AS updated_salary FROM employees;

2. Comparison Operators

These operators are used to compare values.

• = (Equal to)
• != or <> (Not equal to)
• < (Less than)
• > (Greater than)
• <= (Less than or equal to)
• >= (Greater than or equal to)
• BETWEEN (Within a range)
• IN (Matches any value in a list)
• LIKE (Pattern matching)
• IS NULL (Checks for NULL values)
• IS NOT NULL (Checks for non-NULL values)

Example:

SELECT * FROM employees WHERE salary > 50000;

3. Logical Operators

These operators are used to combine multiple conditions in a query.

• AND (True if both conditions are true)
• OR (True if at least one condition is true)
• NOT (Reverses the condition)

Example:

SELECT * FROM employees WHERE salary > 50000 AND department = 'HR';

4. Set Operators

These operators are used to combine results from multiple queries.

• UNION (Combines results from multiple queries, removing duplicates)
• UNION ALL (Combines results from multiple queries, including duplicates)
• INTERSECT (Returns common records between queries)
• EXCEPT or MINUS (Returns records from the first query that aren't in the second query)

Example:

SELECT name FROM employees
UNION
SELECT name FROM contractors;

5. String Operators

These are used for string manipulation.

• CONCAT() (Concatenates two or more strings)
• || (Concatenates strings in some SQL dialects like PostgreSQL)

Example:

SELECT CONCAT(first_name, ' ', last_name) AS full_name FROM employees;

6. Bitwise Operators

These operators perform bit-level operations.

• & (Bitwise AND)
• | (Bitwise OR)
• ^ (Bitwise XOR)
• << (Bitwise left shift)
• >> (Bitwise right shift)

Example:

SELECT 5 & 3;  -- Result is 1 (binary: 101 & 011)

7. NULL Operators

Used to handle NULL values in SQL queries.

• IS NULL (Check if a value is NULL)
• IS NOT NULL (Check if a value is not NULL)

Example:

SELECT * FROM employees WHERE department IS NULL;

These operators help you to filter, compare, and combine data in various ways when writing SQL queries.