Procedure parameters (IN, OUT, INOUT) in MySQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the IN parameter type mean in a MySQL stored procedure?

IN parameters are used to pass values into the procedure. They are read-only inside the procedure and cannot be changed.

beginner

What is the purpose of an OUT parameter in a MySQL stored procedure?

OUT parameters are used to return values from the procedure back to the caller. They can be assigned new values inside the procedure.

intermediate

Explain the INOUT parameter type in MySQL stored procedures.

INOUT parameters allow passing a value into the procedure and also returning a modified value back to the caller. They can be read and changed inside the procedure.

beginner

How do you declare an OUT parameter in a MySQL stored procedure?

You declare it by specifying OUT before the parameter name and its data type, for example: OUT param_name INT.

beginner

Can IN parameters be modified inside a MySQL stored procedure?

No, IN parameters are read-only inside the procedure and cannot be changed.

Which parameter type allows you to pass a value into a MySQL procedure and get a modified value back?

A IN

B INOUT

C RETURN

D OUT

INOUT parameters allow both input and output of values in MySQL procedures.

What happens if you try to change an IN parameter inside a MySQL procedure?

A The value changes and is returned

B An error occurs

C The change is ignored; IN parameters are read-only

D The procedure stops running

IN parameters are read-only inside the procedure, so changes are ignored.

How do you specify an OUT parameter in a MySQL procedure declaration?

A By writing IN before the parameter name

B By writing RETURN before the parameter name

C By writing INOUT before the parameter name

D By writing OUT before the parameter name

OUT parameters are declared by writing OUT before the parameter name.

Which parameter type cannot return a value back to the caller?

A IN

B OUT

C INOUT

D ALL can return values

IN parameters only pass values into the procedure and do not return values.

If you want to get a result from a procedure using parameters, which type should you use?

A OUT

B IN

C INOUT

D None, use SELECT only

OUT parameters are designed to return values from procedures.

Describe the differences between IN, OUT, and INOUT parameters in MySQL stored procedures.

Think about how data flows between caller and procedure.

How would you use an OUT parameter to get a value from a MySQL stored procedure?

Consider the steps to send data back from procedure to caller.