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Mysql insert/update with multiple keys

Posted on 2011-03-20
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Last Modified: 2012-05-11
Hi

I am looking for an easy way to do a mysql insert/replace based on whether the data exists or not.

I have a table with 3 keys, Staff ID, DateRef, Line Ref. There is no single unique key, rather the 3 keys make the record unique.

Can I use multiple keys in REPLACE INTO or ON DUPLICATE KEY UPDATE?
Or do I have to do the SELECT - IF FOUND UPDATE, OTHERWISE INSERT.

Thanks
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Question by:gorrie67
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Expert Comment

by:Sharath
ID: 35178325
If your primary key is defined on three columns, then you can use "ON DUPLICATE KEY UPDATE" clause.
Did you refer this URL for more details.
http://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html
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Author Comment

by:gorrie67
ID: 35184476
Thanks Sharath
I did read the manual, but it made no sense to me when it comes to using 3 columns as the primary key.
An example would be good!
ie  A,B, C fields make up the primary key. D, E, F, G are the remaining fields to be updated.
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Sharath earned 500 total points
ID: 35184604
Did you really try that? Here is an example which I have run on my machine. Check that "ON DUPLICATE KEY", the record is updated.
create table PrimTable(a int,b int, c int, d int, e int, f int, primary key (a,b,c));

insert into PrimTable  values (1,2,3,4,5,6);
select * from PrimTable;
+---+---+---+------+------+------+
| a | b | c | d    | e    | f    |
+---+---+---+------+------+------+
| 1 | 2 | 3 |    4 |    5 |    6 |
+---+---+---+------+------+------+
1 row in set (0.00 sec)

insert into PrimTable  values (1,2,3,7,8,9) on duplicate key update d = values(d),e = values(e),f = values(f);
select * from PrimTable;
+---+---+---+------+------+------+
| a | b | c | d    | e    | f    |
+---+---+---+------+------+------+
| 1 | 2 | 3 |    7 |    8 |    9 |
+---+---+---+------+------+------+
1 row in set (0.00 sec)

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