Question

Ive got a task here to log changes in the database.

So Ive just read about Triggers and that made me interested to try that out.

I got this table in the database were the customer information is described,

(id fornamn, efternam.. etc is the column names and the information underneath is the values)

This table is called “kunder”

id  fornamn     efternamn   adress  ort     postnummer  foretag     telefon         email           personNmr   husNmr  organisationsNmr    produkt     uppringd    prioritet   raderad
15  Peter       Tressing    adress  ort     41676       foretag     071234565       [e-mail]  123456      4       55658794            Nocria      1           0           0

I called this table kunder_log

id  fornamn     efternamn   adress  ort     postnummer  foretag     telefon         email           personNmr   husNmr  organisationsNmr    produkt     uppringd    prioritet   raderad     timestamp   type

(the only diffirance is index instead of primary key on the ID and I added the timestamp and type)

(Type the type of the query (insert, delete or update))

Now i want to trigger changes for each row in the table when i do an Update/Insert/Delete query.

But I only want to insert the changes made and not every column in the old table.

Is this possible or do you recomend another approache?

Answer 1

Basically there are two approaches to log all the changes done on main table:

1. trigger is good option if you want to log all the changes made to tables globally.

2. write insert into change log tables after every insert, update, delete statement in all stored procedures.

I generally prefer second approach as it is much faster as compared to triggers.

Sample table structure:

kunder
    all_columns

kunder_log
    change_log_id INT unsigned NOT NULL AUTO_INCREMENT PRIMARY KEY,
    all_columns
    change_type ENUM('INSERT','UPDATE','DELETE'),
    change_time TIMESTAMP NOT NULL DEFAULT 0,
    change_description VARCHAR(1024)