[Solved] How to refer 2 columns from a single column in mysql [duplicate]

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Consider adding a flag to the User table that indicates if the user is a temporary user or not:

alter table user add is_temp tinyint unsigned default 0 not null;

This will allow a simple foreign key reference from In_Out:

alter table In_Out 
    change id User_id <Match Data Type And Nullness Here>,
    add constraint User_id_fk foreign key (User_id) references User(id);

solved How to refer 2 columns from a single column in mysql [duplicate]