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why DBGrid cannot display New Insert record?

  When I Insert a new record into TTable and Post,
it disppears when i scroll DBGrid. What's the matter
with my DBGrid then?

  I use TTable + DBGrid, and database is Sql Server 7.0
it cannot work fine even if I use Sybase 11.9.2 as my
database, or TQuery as my dataset.

  Best regards!

                                      kjerry

 

Re:why DBGrid cannot display New Insert record?


kjerry,

   Typical behavior when using TTables against a SQL server.  Switch to
using TQuerys and either use CachedUpdates or TClientDatasets to update the
data.

Check out:
http://community.borland.com/article/0,1410,22571,00.html

and (this is from Wayne of TeamB):

=================================================
TTables vs. TQuerys

The whole reason there is both a TTable and a TQuery component is due to the
fact there table-oriented databases like Dbase, Paradox, or Access, and
there are set-oriented databases like Interbase, Oracle, and MSSQL. These
different types of database systems work and behave completely different
from one another and the same methods of access cannot be equally applied.

TTable is specifically designed to work best with table-oriented systems -
it is "native" to them. Using a TQuery against such databases is slower
because they do not understand SQL and so the BDE must interpret the SQL and
convert it to table calls for that database.

TQuery is specifically designed to work best with set-oriented databases
that understand SQL directly and were designed to work this way. Using a
TTable against such a system is slower because the BDE must convert the
table functions into SQL instructions to be sent off to the database.

Some of the things that TTables do that eat time and resources over a
network with an SQL system are:
- on Opening, always sends many queries to the database to get all the
metadata for all fields and indexes in the selected table in order to
provide you with a selection of these (only *Live* TQuerys do this).
- if you have large records with many fields, TTable will always select ALL
fields even if you only want one or two. This is especially bad if the table
contains blobs and you do not need them.
- Using Locate or FindKey or RecordCount forces all records to be fetched
because such searching / counting has to be done on the client side. This
can be eased by using a good filter (in the Filter property, not the
OnFilter event) to limit the records that need to be fetched (Filters are
turned into SQL where clauses by the BDE).
- if used in a grid, TTable must frequently execute multiple queries to fill
the grid whenever you change record positions.
- Tables prevent you from using the power of SQL when working against a real
SQL server - they only see physical tables (or views in SQL systems),
whereas you can write TQueries to slect any raltionships between and number
of tables and get only *exactly* the data you need.

With TQuerys, you still need to use them right to get the most out of them,
but the point is that you *can* use them right with regard to SQL databases.
- with the exception of extremely small "lookup" type tables (e.g. State
codes) *always* use where clauses to limit the number of records brought
back, if you do not then you are defeating the whole purpose of using them.
- unless you *really* need to every field in a table, always specify the
fields you actually need (e.g. "select cust_id, cust_name from...", not
"select * from..."). A tip here is to avoid editing records in a grid, use
grids only for selection. This allows you to only select the minimum fields
needed for selection, then use another query to select all fields for that
ONE selected record for editing purposes.
- Never use the Filter property or OnFilter event, or call RecordCount with
a TQuery, this forces the entire record set to be fetched. If you really
need the record count, use another query to get it so the server will do the
counting and send back the count itself instead of all the records.

--
Wayne Niddery (WinWright Inc.)
RADBooks - http://members.home.net/wniddery/
I love deadlines. I like the whooshing sound they make as they pass by -
Douglas Adams

-------------------------------------------------

Re:why DBGrid cannot display New Insert record?


hi, Kevin Frevert

    Thank you for your suggestion.But I had tried TQuery
before I use TTable as dataset. The same as TTable, I
cannot saw any new inserted record. When I set TQuery with
CacheUpdates, It seems a good way, the new inserted record
can display very well. But if you try to delete or modify
it immediately, errors occur.(After post and applyupdates).
    Nice to getting your help again and Best regards.

                                                kjerry

Quote
Kevin Frevert <kfrev...@midwayusa.com> wrote in message

news:3a1bc468$1_1@dnews...
Quote
> kjerry,

>    Typical behavior when using TTables against a SQL server.  Switch to
> using TQuerys and either use CachedUpdates or TClientDatasets to update
the
> data.

> Check out:
> http://community.borland.com/article/0,1410,22571,00.html

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