Why is it saying ' DECLARE' (declare) is not valid input at this position?

[Mark Kamoski]

Dear MySql Workbench Pros --

Please help a newbie to MySql Workbench.


Why is it saying ' DECLARE' (declare) is not valid input at this position?


-- This does work...


SELECT * FROM alerts WHERE update_number = 0;


-- This does NOT work...


-- Syntax error: 'DECLARE' (declare) is not valid input at this position

DECLARE @update_number INT;


SET @update_number = 0;


SELECT * FROM alerts WHERE update_number = @update_number;


...so WHY is that syntax not correct?


I noticed that I can just skip the DECLARE line altogether, but then my question is how is the variable datatype set when the DECLARE line is omitted? Is the datatype set dynamically based on the value assigned with the SET there? Or what?

So, is there a way to use the DECLARE statement in such a case?

Please advise.

(This is specifically about the DECLARE syntax. I have read about user-defined-variables and local-variables and system-variables. So I am wondering about the use of the DECLARE keyword in the example above and how the data-type is set when the DECLARE keyword is not used, etc.)

Thanks.

-- Mark Kamoski