Thanks Pierce - I go the drift of the loop but have actually tried it out with the odbc<->sqlite driver
however in your notes below you mentioned that you used a dump of large size. My question is when faced with such large row sets how do you limit the size of data read in the select statement . Select * from table would probably read in the entire table set, and the limit clause would stop and not go beyond the no# of rows specified. another doubt I had was from the example code below from the NBSQLite3. is rs close at the right place - would it be closing the connection ? res := db beginTransaction. rs := db execute: '...'. rs close. res := db commitTransaction. regards Sanjay Pierce Ng-3 wrote > On Thu, Apr 30, 2015 at 06:29:53AM -0700, Sanjay Minni wrote: >> the smalltalkhub page shows an example >> db execute: 'SELECT * FROM BLOGPOSTS;'. >> but how are the rows supposed to be accessed - in the tests i see they >> have >> to be walked thru one by one like a 3GL loop > > Sanjay, > > Here's how you can collect all rows: > > | db resultSet row coll | > coll := OrderedCollection new. > db := NBSQLite3Connection openOn: '/tmp/so.db'. > [ resultSet := db execute: 'select * from posts limit 10'. > [ (row := resultSet next) notNil ] whileTrue: [ > coll add: row ] > ] ensure: [ db close ]. > coll inspect. > > Each row is an NBSQLite3Row instance. Use #at: with the column name as key > to get at the data. > > coll fifth at: 'Title' > ==> 'How do I calculate someone''s age in C#?' > > With the collection you still have to loop through them, no? > > I am using NBSQLite3 to play with existing data, and I haven't worked with > enough different types of data to attempt to generalize a looping > construct. So > I've always done by-row processing. > > Another reason is that, while my data sets aren't "Big Data", I am > aesthetically inclined against reading everything into RAM. :-) Above > example > uses the Sep 2011 StackOverflow data dump. The SQLite datafile created > from the > dump, with full text indexing, is 16GB and the table posts has ~6.5 > million > rows. > > HTH. > > Pierce ----- --- Regards, Sanjay -- View this message in context: http://forum.world.st/Reading-rows-in-a-database-table-select-from-tp4823000p4823522.html Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
