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From:Martin B. Jespersen Date:March 22 1999 2:23pm
Subject:How to make a joint primary key of two or more fields
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Well there it is, all in the subject.

I can't figure out how to make two fields function as a single primary key and thus have
an unique check on them both but not

This might be a big RTFM to me, but i haven't been able to find documentation taht i
understand about it.. all i found was:

A PRIMARY KEY can be a multiple-column index. However, you cannot create a multiple-column
index using the PRIMARY KEY key
attibute in a column specification. Doing so will mark only that single column as primary.
You must use the PRIMARY
KEY(index_col_name, ...) syntax.  

it says i have to use PRIMARY KEY(index_col_name, ...), so does the collumns i use for the
joint primary have to be indexes? 

lets say i have a table with two int's and one varchar and i want all three to be the
primary key together.

i figured i could just do:

alter table my_tbl ADD PRIMARY KEY (int_col1,int_col2,varchar_col1);

but somehow it didn't do the trick for me (i think)... i am out where i have a hard time
reaching the bottom, anyone care to get
me to shore? :-)

Please bend that syntax in neon for me, and please include an example. :-)

Martin B. Jespersen
Technical Project Leader
Icon Medialab A/S (

E-Mail: Martin@stripped
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How to make a joint primary key of two or more fieldsMartin B. Jespersen22 Mar
  • Re: How to make a joint primary key of two or more fieldsChristian Mack23 Mar