Question

example

tag  { id PK, name TEXT };
item { id PK, exampleData LONG, tagId LONG //or foreign key depending on provider }

i’m using SQLite and C#. Is it proper to

1. Start a transaction
2. Insert into tag
3. If affected rows = 0 do a select to get tag.PK otherwise use last_insert_rowid
4. Insert item

or will there be a problem with the above? I plan to switch to MySql or TSQL

Answer 1

You can conditionally insert the tag if it doesn’t exist like:

insert into tag (name)
select 'NewTagName'
where not exists (select * from tag where name = 'NewTagName')

Then, while inserting the new item, you can query the tag id:

insert into item (exampleData, tagid)
select 'NewData', (select id from tag where name = 'NewTagName')

This method doesn’t require retrieving the id of the inserted row, and will work fine without a transaction.