Check out example codes for "mysql declare variable". It will help you in understanding the concepts better.

Code Example 1

SET start = 1;
SET finish = 10;

SELECT * FROM places WHERE place BETWEEN start AND finish;

Code Example 2

-- MySQL

DECLARE variable_name datatype(size) [DEFAULT default_value];
-- Declaring a variable without specifying a default value will result it
-- in being a null value.
-- Declare is what allows us to create a variable

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