Cross-table UPDATE in SQLITE3

Just to emphasize Geogory Higley's post:

I have had problems with UPDATE tbl1 SET col2 = (SELECT col2 FROM tbl2 WHERE tbl2.col1 = tbl1.col1) where it updates columns in tbl1 that do not exist in tbl2.

see cheetah post at http://sqlite.phxsoftware.com/forums/p/1708/7238.aspx which points to:

http://www.mail-archive.com/[email protected]/msg27207.html

The code is:

insert or replace into foo (id, name, extra)
select bar.id, bar.name, foo.extra
  from bar 
  left join foo 
    on bar.id = foo.id;

and this seems to work correctly. There seem to be many posts at different sites that recommend the first approach so it is a bit confusing. I would suggest you test your output very carefully if you use this method which does seem faster and may work with matched tables.

This works for sqlite:

UPDATE tbl1 SET col2 = (SELECT col2 FROM tbl2 WHERE tbl2.col1 = tbl1.col1)

For what it's worth, Microsoft SQL Server and MySQL are the only brands of database that support multi-table updates, and the syntax each uses is not similar.

This feature is not part of standard SQL. So it's not surprising that support for multi-table update (and delete) is nonstandard and not supported by many brands.

Anyway, I'm glad you found a solution that works for your task.

I've discovered this can be done with INSERT OR REPLACE INTO. A little more verbose than T-SQL's equivalent, but just as handy.