Use Variables in MySQL Workbench

• In MySQL Workbench, you can create and use variables to store and manipulate data within your SQL queries. Variables can be helpful for storing temporary values, making your queries more dynamic, and simplifying complex queries.

Here's how you can create and use variables in MySQL Workbench:

• Creating Variables: You can declare and assign values to variables using the `SET` command.

    SET @variable_name = value;

• We can create and access variable value on this way.
  

    SET @name = "gagan";

    SELECT @name

• Now consider an example:

    SET @user_id = 123;

    SET @max_age = 30;

    SET @today = CURDATE();

• Using Variables in Queries: You can use the variables you've created in your SQL queries by referencing them with the "@" symbol.

    SELECT * FROM users WHERE id = @user_id;

• You can also use variables in expressions:

    SELECT * FROM users WHERE age <= @max_age;

• And in combination with functions:

    SELECT * FROM orders WHERE DATE(order_date) = @today;

• Updating Variables: You can update the value of a variable using the `SET` command again.

    SET @user_id = 456;

• Using Variables in Mathematical Operations: Variables can also be used in mathematical operations within queries.

    SET @total_price = @quantity * @unit_price;

    SELECT @total_price;

Important Notes:

• Variable names in MySQL are case-insensitive. So, `@user_id` and `@User_id` are treated as same variables.

• MySQL variables have a session scope. They are available only within the session in which they were declared and set.

• Remember that using too many variables can make your queries harder to read and maintain. Use variables when they genuinely improve the readability and efficiency of your queries.

• By understanding how to create and use variables in MySQL Workbench, you can make your SQL queries more dynamic and flexible.