[MySQL]Insert a value depending on a condition

Question

I'm studying MySQL so I'm a bit new to all this stuff, but the last time I asked you guys, you proved to be really helpful, so perhaps you can help me again because I haven't been able to find the answer on my own.

Ok, so the thing is, I need to add a new column to an already existing table, and it should be like:

ALTER TABLE `medicos` 
ADD COLUMN `tipo_medico` VARCHAR(20) NOT NULL DEFAULT 'indiferente' AFTER `sueldo`;

Now I'm supposed to run an INSERT instruction to add the data there. After adding that column, the table looks like this:

These values equal to: Medic_number, Surnames, Speciality, Day of birth, University, Wage and Medic_type (the new column I've added). The data I add on all the columns except the last one doesn't really matter, but the last column must be filled following the next conditions:

-By default, it'll be "indiferente" (that's working).

-If a medic has studied in an university ending in -a (ie Valencia), it'll say "Excellent".

-If a medic is 40 years old or older, it'll say "Expert".

Now, I know how to do these conditions ("... university like = '%a'", etc), but I don't know how to add that into the INSERT instruction. This is what I've gotten so far:

insert into medicos values ('A021', 'Apellidos :D', 'Loquesealogia', '1970-03-14', 'Valencia', '3500');

That adds everything but the last column, which is the one where I'm lost. What can I do to tell the INSERT instruction to, depending on which of the previously named conditions are true, add one value or another?

I hope I've been clear enough, I'm not a native English speaker so I'm sorry if that wasn't good enough. Also I've tried to format the codes this time, I hope that'll work.

Thanks.

Answer 1

This seems to be a case when we need to apply a logic on column values before a record is inserted. I would suggest creating a BEFORE INSERT trigger on this table, which will be automatically executed by MySql before each record is inserted.

We can write the logic to determine the value of last column depending upon values supplied for the other columns. Have a look at this link for trigger example.

If the requirement here is to do a one time bulk insert then, we can drop this trigger once insertion is complete.

Answer 2

I would advise you to do it either with BEFORE INSERT trigger as Darshan Mehta recommends, or do your logic in the programming side, or with a stored procedure.

Still it is doable at query time, so to answer your question specifically, try something like this:

INSERT INTO medicos (num_colegiado, apellidos, especialidad, fecha_nac, universidad, sueldo, tipo_medico) SELECT 'A021', 'Apellidos :D', 'Loquesealogia', '1970-03-14', 'Valencia', '3500', IF('Loquesealogia' like '%a','Excellent',IF(DATE_ADD('1970-03-14', interval 40 YEAR)>NOW(),'Expert','indiferente'))