Hi

I have a table with much fields ( 200-300 )

i need open this table , seek on record and result a field.

i need this in FAST MODE

My generic code now :

table.Create
table.Open      <- SLOW
table.GotoKey
Result :=  table.FieldByaname('NameField_1').AsString
table.Close
table.Free

but it e' too slow.


Is there a optimized command for read only one field value from a big table
?
( big table = much fields , i have only 100-200 records )


i should edb don't read all 200 fields structure, in open
i need only NameField_1 when Open is occured.

i have try with TEdbTable at RunTime , with FieldDef defined
( only one field in list : NameField_1 )

don't work ,  EDB read always all 200 fields ( it is slow to open table )

Hint ?



Delphi 2009 + EDB 2.0 B10 , NO C/S

Mauro


From your other post you had a table with 2 columns taking a long time to open now you have one with 200 fields and you're blaming the number of columns.

You haven't said how slow it is, wether its being used in a loop or what.

I'd recommend trying sql for something like this. A simple SELECT statement will work in pseudo code

create query
query.sql.text = 'SELECT NameField_1 FROM table WHERE selection criteria'
query.open
Result :=  query.FieldByaname('NameField_1').AsString
query.Close
query.Free

If its a one off that's about as fast as you'll get as long as you make sure you have appropriate indices on the selection criteria. If its in a loop or multiple times then

initialise the query
create query
query.sql.text = 'SELECT NameField_1 FROM table WHERE selection criteria'
query.prepare
and leave it available

use the query
query.close
query.parambyname(xx).aswhatever := selection
Result :=  query.FieldByaname('NameField_1').AsString


finally get rid when no longer wanted (eg in FormClose)
query.Close
query.unprepare
query.Free


Roy Lambert [Team Elevate]

Mauro,

<< I have a table with much fields ( 200-300 )

i need open this table , seek on record and result a field.

i need this in FAST MODE >>

The fastest way would be to use a TEDBQuery component instead, like Roy
indicated.  Using a TEDBTable will result in all of the columns being loaded
into TFieldDefs, at the very least, with TFields being created for all of
them in the default case.  You can use just one persistent TField by
double-clicking on the TEDBTable and just adding the one desired field to
the list of persistent fields, and that will cut down on the time a bit, but
the query will always be the fastest method.

--
Tim Young
Elevate Software
www.elevatesoft.com