find diffrences between 2 tables sql and how can i get the changed value? - sql

Question

i have this query
insert into changes (id_registro)
select d2.id_registro
from daily2 d2
where exists (
select 1
from daily d1
where
d1.id_registro = d2.id_registro
and (d2.origen, d2.sector, d2.entidad_um, d2.sexo, d2.entidad_nac, d2.entidad_res,
d2.municipio_res, d2.tipo_paciente,d2.fecha_ingreso, d2.fecha_sintomas,
d2.fecha_def, d2.intubado, d2.neumonia, d2.edad, d2.nacionalidad, d2.embarazo,
d2.habla_lengua_indig, d2.diabetes, d2.epoc, d2.asma, d2.inmusupr, d2.hipertension,
d2.otra_com, d2.cardiovascular, d2.obesidad,
d2.renal_cronica, d2.tabaquismo, d2.otro_caso, d2.resultado, d2.migrante,
d2.pais_nacionalidad, d2.pais_origen, d2.uci )
<>
(d1.origen, d1.sector, d1.entidad_um, d1.sexo, d1.entidad_nac, d1.entidad_res,
d1.municipio_res, d1.tipo_paciente, d1.fecha_ingreso, d1.fecha_sintomas,
d1.fecha_def, d1.intubado, d1.neumonia, d1.edad, d1.nacionalidad, d1.embarazo,
d1.habla_lengua_indig, d1.diabetes, d1.epoc, d1.asma, d1.inmusupr, d1.hipertension,
d1.otra_com, d1.cardiovascular, d1.obesidad,
d1.renal_cronica, d1.tabaquismo, d1.otro_caso, d1.resultado, d1.migrante,
d1.pais_nacionalidad, d1.pais_origen, d1.uci ))
it results in an insersion data that doesn't exist in another table, that's fine. but i want know exactly which field has changed to store it in a log table

Answer 1

You don't mention precisely what you expect to see in your output but basically to accomplish what you're after you'll need a long sequence of CASE clauses, one for each column
e.g. one approach might be to create a comma-separated list of the column names that have changed:
INSERT INTO changes (id_registro, column_diffs)
SELECT d2.id_registro,
CONCAT(
CASE WHEN d1.origen <> d2.origen THEN 'Origen,' ELSE '' END,
CASE WHEN d1.sector <> d2.sector THEN 'Sector,' ELSE '' END,
etc.
Within the THEN part of the CASE you can build whatever detail you want to show
e.g. a string showing before and after values of the columns CONCAT('Origen: Was==> ', d1.origen, ' Now==>', d2.origen). Presumably though you'll also need to record the times of these changes if there can be multiple updates to the same record throughout the day.
Essentially you'll need to decide what information you want to show in your logfile, but based on your example query you should have all the information you need.