Same-step and different-step execution mode in ODBC

 

 

---- In the recent years, with the continuous development of computing and server domain network technologies

 Build the customer machine/server model that has been developed to be complex and open

. For the development and release of the Client/Server, which is usually used before the project

Development tools availableVisual Basic, Visual Foxpro, Delphi, PowerBuilder, etc,

They can pass throughODBC access to the SQL Server data warehouse Server of the Server

Generally, there are three methods.(This document uses ODBC 2.0 as an example ):

 

Use of data control items;

 

Use the data base to edit the image volume;

 

Direct callODBC 2.0 API.

---- ODBC 2.0 Data Access database stored in the same step and different step Execution Mode

Points, if the design is not appropriate, it is easy to generate a system fault and even a system dead lock. Lower

 The face-to-face operator implements the same step and different step of ODBC 2.0.

Let's talk about how to use the tested and set-up methods to be renewed with the same bank.

 

Same-step Execution Mode---- The same-step execution mode means that the sentence is in the same

In the step-by-step mode, the system controls the start and end-by-end traffic to the Process

End in sequence. In the case of query operations, the user's host should be directed to the server in a sequential manner.

After sending the request instructions, wait until the server completes the query.

If it is returned to the client, the next step is continued.

---- All week-wise users should delete all

Recording will be time-consuming. For example, if the program sequence is used

(Thread) in the same step, the deletion of a job can delay

Complete the work. If it is necessary to use the process sequence and so on,

Then, Remote Server failure or network failure or unexpected

All situations can allow the application to go down with no limit period in the process sequence. This is the same step.

The biggest weakness of the execution.

 

 

---- But it is the complexity that the same-step execution model can be compiled in simplified procedural order.

 Programmers can describe the ODBC 2.0 API that is more complex than others.

Use, but only useThe same-step execution mode of ODBC or Data Control

Programming item and data warehouse to change the image volume to compile the program order, which can be increased

The launch efficiency, but the speed of the sequential operation is less than the speed of the same step

 Degree.

 

Xtep Running Mode---- The form that refers to the delivery of different steps means that the sentence is different

In the form of step-by-step execution, the execution of each sentence is in the ascending order and the opening of each sentence.

The first order is not necessarily the same. For example, for query operations

After a request instruction is issued to the server in the query procedure

 Indicates the next sentence of the order, and does not need to wait to arrive at the server.

The server returns the query result to the client.

---- The implementation method of different steps enables the process to take off a single task,

It improves the flexibility and the execution efficiency of application procedures. But the same step execution model

Style is also stored in some questions, such as it adds the complexity of the compilation process, special

Is the interaction between coding and writing.(Interoperable) to obtain a higher order.

 

---- In the customer/Server System with heavy load, it is appropriate to use different

Step execution mode. In this environment, time delay, frequency delay, and time delay,

The start-up and sales of different steps of the phase comparison are slightly inadequate. However, if yes

If the environment ratio of the transportation industry is complex, a complete machine system must be established,

 The status of weekly checklist statement execution to determine the next step.

Solutions. The weekly check can be performed by using multiple methods, such as in use

Set and handle the timerWM_TIMER information.

 

---- Although it is complicated to execute the model with different steps in programming

You can execute multiple tasks in real time to increase the execution efficiency.

 

Select and set the Execution Mode---- Select the same step in the application process

The model is also a different-step model, which is a layer that is more complex than the complex one. When querying

Or when the data warehouse is modified to a pair of simple orders, the same-step execution mode is

A good choice. It can return the result in seconds or less.

Data. In addition, the execution cannot be continued until the result set is obtained in the applicable procedure.

The root node does not need to execute the model in different steps. Complex query Conditions

Is a complex multi-row data warehouse.UPDATE or DELETE operations.

It takes a long time to complete the process. You need to use a different step to execute the model,

Let the user perform operations on his/her parts of the process in the same time.