what is the primary key of a table?

[jerryt]

Hi there,

I'm using Helsinki and I'm wondering what is the primary key in a table.

It looks that most of the tables have a column 'sys_id', which seems like the primary key in that table. When I navigate to 'Tables and Columns', I see a big blue circle icon with an 'i' inside beside sys_id:

But some tables don't have sys_id. For example, pa_favorites and v_db_index seem not to have primary keys.

There's another interesting table. ts_word_roots has 3 columns and they are like this:

So my questions are:

1. How can I check what is the primary key in a table? (usually sys_id I guess, but I'm not sure)

2. Are there any tables without primary keys? (like pa_favorites and v_db_index?)

3. For table ts_word_roots, does it have a composite primary key?

Thanks a lot!

[Chuck Tomasi]

Hi Jerry,

The "I" icon represents the field is indexed.

You are correct, in most cases, sys_id is the primary key. Where there is no primary key, I don't know, but I'll check. Interesting question.

Why the interest in database details?

[jerryt]

Thanks Chuck, our team is making an ODBC driver which uses ServiceNow as data source, so we need to know some database details.

So if a table has sys_id as a column, then we can consider sys_id as the primary key, is that always the case?

I haven't done any changes to the tables in my sandbox yet, so by default sys_id is the primary key?

[Chuck Tomasi · Accepted solution]

Hi Jerry,

Yes, where there is a sys_id, that's the primary key. I checked some of the others you mentioned and here's what I found.

• pa_favorites - PRI=user
• v_db_index - PRI=sys_id
• ts_word_roots - PRI=index,raw_word,stemmed_word

Let me know if there are any other specifics you need.

[jerryt]

Thanks Chuck, does v_db_index has sys_id? I only see a column 'index'. Is it the primary key? Or do I need to set it as the primary key?