Row updating in vb net

28-Dec-2016 08:39

NET Data Adapter and serialisable Data Table are the hinge pins of ADO. These classes provide a way to expose one or more rowsets and a mechanism to update the data. The Data Adapter is not really a new idea born with ADO. Its roots come not from Tao, but from the DOW – the Data Object Wizard first introduced in Visual Basic 6.0 but henceforth abandoned in light of the innovations in Visual Studio. The DOW was used to generate a class that fetches a rowset and defines the UPDATE, DELETE and INSERT SQL needed to manage the rowset. It also sports a facility to automatically generate the action queries – but regrettably, only for "home" database challenges.

This is a new mechanism for data access developers writing code for all application architectures. NET Data Provider, the Data Adapter is implemented as the System. One of the most significant differences between COM-based ADO "classic" (ADOc) and ADO. In ADOc, action SQL was generated on the fly controlled by the Update Criteria and other properties.

Once the data is downloaded into Data Table objects, it's a simple matter to construct relationships between them.

Updating is also straightforward in this case, and if the Select Command is simple enough the Command Builder can be used to generate the action commands (not that I recommend doing so).

Developers, yearning for better performance, often lean toward the low-level Data Reader approach – rolling their own update code or using the Command methods to execute stored procedures which update the source tables. To String Depending on how the Data Adapter is configured, the Fill method either creates a new Data Table for each rowset returned, or cleverly "updates" the Data Table objects already constructed in a selected Data Set.

No, it's not really a batch in the traditional sense, but that's what Microsoft chose to call it. NET walks the set of rows passed to the Update method and executes either the Update Command, Delete Command or Insert Command based on the row's Row State value. That said, I also think some developers lose sight of what makes a program perform and scale to its full potential. This means you'll need an example of fetching selected columns focused (and limited) by a WHERE clause for your production application that extracts rows from that 100,000 (or 1,000) row table (assuming you want to build a scalable application).

This article walks you through several data access strategies that take advantage of features implemented by the Data Adapter. It did not require an extra round trip to generate this SQL, but it did require a bulkier SELECT FOR BROWSE to return schema information needed to construct these action commands. NET takes another approach – it leaves the generation of the update commands up to the developer.

Note that the Data Adapter is implemented by each of the . This means that developers have far more flexibility in how updates are posted to the data.

If I run the code again, the Fill is repeated and ADO.

NET adds any rows returns to the existing tables created in the first pass instead of creating a new Data Table. NET sees that the schema for the inbound rowset matches the schema of the existing Data Table(s). For example, in the case of SQL Server, if you leave the Missing Schema Action property set to its default state (Missing Schema Action.

No, it's not really a batch in the traditional sense, but that's what Microsoft chose to call it. NET walks the set of rows passed to the Update method and executes either the Update Command, Delete Command or Insert Command based on the row's Row State value. That said, I also think some developers lose sight of what makes a program perform and scale to its full potential. This means you'll need an example of fetching selected columns focused (and limited) by a WHERE clause for your production application that extracts rows from that 100,000 (or 1,000) row table (assuming you want to build a scalable application).

This article walks you through several data access strategies that take advantage of features implemented by the Data Adapter. It did not require an extra round trip to generate this SQL, but it did require a bulkier SELECT FOR BROWSE to return schema information needed to construct these action commands. NET takes another approach – it leaves the generation of the update commands up to the developer.

Note that the Data Adapter is implemented by each of the . This means that developers have far more flexibility in how updates are posted to the data.

If I run the code again, the Fill is repeated and ADO.

NET adds any rows returns to the existing tables created in the first pass instead of creating a new Data Table. NET sees that the schema for the inbound rowset matches the schema of the existing Data Table(s). For example, in the case of SQL Server, if you leave the Missing Schema Action property set to its default state (Missing Schema Action.

If you're working with home databases or those in your office with only a few hundred rows, and you aren't concerned with multi-user issues (and never plan to be), whether or not you fetch all of the rows from the table won't make much difference. This is called optimistic programming, or programming by wishful thinking.