Question

I am trying to move data from one table into two new tables, but I am unsure how I can do this in the best and most foolproof way.

I have about 2000 rows in newsletter_users that looks like this:

userid company email memberofgroup

where

memberofgroup 

is an integer that refers to newsletter_mailgroups. This is not the best way if a user wants to be a member of different groups. Then there will be x rows with the same email. 2000 users x 3 or 4 different groups (what did I think of??) Therefore I have made two new tables

newsletter_members that look like this

userid email company

and another table newsletter_member_of_group that look like this:

field_member_uid field_user_id field_memberofgroup

where

field_user_id

will contain a users id from newsletter_members and

field_memberofgroup 

will contain the emailgroup id. f.x.

field_user_id  field_memberofgroup 
    2                 6
    2                 4
    2                 8
    3                 1
    5                 6

How can I export and then import them in the best way so that emails will not duplicate in newsletter_members? – I might need to do a manual check to see which users a members of more than one mailgroup.

Mailgroups table:

1   Forhandlere 
2   Arkitekter og byggerådgivere   
3   Typehusfabrikanter  
4   Byggeentreprenører 
5   Murermestre 
6   Tømrermestre   
7   Tagdækkere 
8   Boligforeninger/Ejendomsselskaber   
9   Bygge-interesserede 
10  Tyske modtagere 
11  Landskabsarkitekter 
12  Norske arkitekter   
13  Svenske arkitekter  
14  Norske forhandlere  
15  Svenske forhandlere 
16  Brancherelaterede   
17  Svenske ansatte 
18  Norske ansatte  
19  Beijer Sverige  

Answer 1

The solution in few steps:

• Craete table newsletter_member_of_group.

Script:

 CREATE TABLE newsletter_member_of_group(
  field_member_uid INT PRIMARY KEY AUTO_INCREMENT,
  field_user_id INT,
  field_memberofgroup INT
);

Note that field_member_uid is AUTO_INCREMENT, it will help us to insert ID values.

• Copy data from newsletter_users to newsletter_member_of_group.

Script:

INSERT INTO newsletter_member_of_group
  SELECT NULL, userid, memberofgroup FROM newsletter_users;

• Create newsletter_members table. We have two variants: create new table and copy data, or rename newsletter_users to newsletter_members and drop memberofgroup field. I choose second variant.

Script:

ALTER TABLE newsletter_users RENAME TO newsletter_members;
ALTER TABLE newsletter_members DROP COLUMN memberofgroup;