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SQL Functions

Functions#

Functions in MySQL are reusable blocks of code that perform a specific task and return a single value.

Purpose: Simplify complex calculations, enhance code reusability, and improve query performance.

Types: Built-in Functions and User-Defined Functions (UDFs).

  1. Built-in Functions

    a. String Functions (e.g., CONCAT, LENGTH, SUBSTRING)

    b. Numeric Functions (e.g., ABS, ROUND, CEIL)

    c. Date and Time Functions (e.g., NOW, DATE_FORMAT, DATEDIFF)

    d. Aggregate Functions (e.g., COUNT, SUM, AVG)

  2. User-Defined Functions (UDFs) Custom functions created by users to perform specific operations. It is customizable, reusable, and encapsulate complex logic.

                DELIMITER $$
            CREATE FUNCTION function_name(parameter(s))
            RETURNS data_type
            DETERMINISTIC
            BEGIN
            -- function body
            RETURN value;
            END $$
            DELIMITER ;