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Update parent table id from old table that has relation

Posted on 2014-09-04
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Last Modified: 2014-09-15
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I am creating new tables in my database because im trying to normalize them.

I am having to update these new tables with my old data.

i have populated tbl_activity and tbl_class from results_class table

I have also populated tbl_activity_class with all the class id's from tbl_class.

Now i need to update tbl_activity_class with my activity_id's from tbl_activity.

results_class has the right relationships between activity and class

How can i update tbl_activity_class activity_id from tbl_activity activity_id where results_class activity and class match class_id of tbl_class.

hope i explained this well enough.
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Question by:bignadad
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Author Comment

by:bignadad
ID: 40306138
I came up with this to get the data into a tmp table so i could easily get it into the table needed.

However its taking forever to execute. Is there a quick way to run this query?

INSERT INTO tbl_activity_copy (activity_id, activity,class_id,class)
SELECT
  tbl_activity.activity_id,
  tbl_activity.activity,
  tbl_class.class_id,
  tbl_class.class
FROM tbl_class
  INNER JOIN results_class
    ON tbl_class.class = results_class.class
  INNER JOIN tbl_activity
    ON results_class.activity = tbl_activity.activity

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Expert Comment

by:Aaron Tomosky
ID: 40306346
looks pretty basic, do you have indexes on those columns you are joining on?

Try doing left joins for this insert, then delete rows with null you don't want after. that might go faster.
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Author Comment

by:bignadad
ID: 40306432
i have index on results_class activity and class unique.

What might that look like?
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LVL 38

Expert Comment

by:Aaron Tomosky
ID: 40306570
Instead of inner join use left join
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Author Comment

by:bignadad
ID: 40306743
I tried left and it takes longer to run select query.

With either inner or left when I add insert the query takes forever then times out.  What are my options?
I'm using dbforge
0
 
LVL 38

Expert Comment

by:Aaron Tomosky
ID: 40306835
are you truncating the table first?
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Author Comment

by:bignadad
ID: 40306840
The tmp table I'm inserting to?  Yes. It's empty
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LVL 38

Expert Comment

by:Aaron Tomosky
ID: 40306850
I'm out of ideas, it's a simple query, not much to optimize. I suppose it could be running out of memory or something.
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Author Comment

by:bignadad
ID: 40306856
Hmm.  Im not sure what's going on. The tables are both over 100k rows.

I'll post more details and sample data when I get to pc
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Accepted Solution

by:
Tomas Helgi Johannsson earned 500 total points
ID: 40308419
Hi!

Are the columns  activity_id in tbl_activity and class_id in tbl_class auto_increment fields ?
If not you should consider that. Note the tbl_activity_class should not have auto_increment fields.

Then populating the tables would be as follows
insert into tbl_activity (activity) select distinct activity from results_class ;
commit;
insert into tbl_class (class ) select distinct class from results_class;
commit;
insert into tbl_activityclass (activity_id, class_id ) 
   select a.activity_id, c.class_id 
   from tbl_activity a, tbl_class c, results_class r
   where a.activity = r.activity
   and c.class = r.class;
commit;

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Make sure that you have the following indexes

index on activity_id on tbl_activity
index on class_id on tbl_class
and
index on (activity_id, class_id ) on tbl_activity_class
index on (class_id, activity_id ) on tbl_activity_class

Those indexes will speed up selects on your tables.

Regards,
      Tomas Helgi
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