HELP! How to perform Datediff with difference between columns and not current_date?

Question

I’m in need of a simple, data difference (DIA) feedback on Firebird, but I’m not getting the feedback and try many ways ...

the Command below works ...

Datediff (day from Max (distinct TRAVEL.DATE) to current date) as Dias_viag,

However, I don’t want it to make a difference about the current data but another column ... An example that doesn’t work, but needs the difference ..

Datediff (Max Day (distinguished TRAVEL.DATE) for TRAVEL.DATE arrives) as Dias_viag,

Can you help me?

Datediff (Max Day (distinguished TRAVEL.DATE) for TRAVEL.DATE arrives) as Dias_viag,

I hope you return example:

travel.date left = 20/09/2019 - travel.date arrives = 21/09/2019 {1}

Answer 1

Friend, you can use the command Datediff() informing the columns you want.
For example imagine you have the following table:

create table Dados(
    id int not null primary key,
    data_ini date default current_date,
    data_fim date default current_date
);

In case you want to catch the days of difference enter data_ini and data_fimcan use select:

select datediff(day, data_ini, data_fim) from dados;

Note, the command 'DATEDIFF()' accepts entries in date,time and timestamp format, check if the type of data recorded in the columns you want to calculate is the same type as the function accepts, otherwise you should format them.