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This article mainly introduces the relevant knowledge of "what is the difference between SQLHelper and three-layer Age self-increment". Xiaobian shows you the operation process through actual cases. The operation method is simple, fast and practical. I hope this article "what is the difference between SQLHelper and three-layer Age self-increment" can help you solve the problem.

three-layer

Three-tier is just a relatively good software architecture, not necessarily three-tier.

UI layer UI;

Data Access Layer (DAL);

Business Logic Layer (BLL). Entity class is Model; the code for operating on data is written in DAL, generally SQL statement, DAL only operates on data, there is no logic such as "if the amount is greater than 20, cannot delete";BLL calls the code in DAL for logical operation, such as "if the amount is greater than 20, cannot delete." SQL statements, ADO. Net classes should generally only appear in DAL.

First compare the difference between SQLHelper and three-layer Age self-increment.

Let's start with a SQLHelper self-increment.

1. Design winform form

Below we add configuration files and SqlHelper directly

Second, add configuration files and SqlHelper

III. Add references

IV. Add configuration files

This way both the configuration file and the SqlHelper are present.

First of all, think about whether to make sure the Sql statement before writing it.

5. Determine Sql statements

VI. VS Code

VII. SqlHelper execution results

Next, we use three layers to achieve automatic aging:

8. Write a winform

Add profiles and SplHelpers and add references as in the previous question.

Three layers of writing must be clearly distinguished.

Just written winform can be understood as the interface layer UI. Of course, you can also use ASP.NET web pages to express, or mobile phone pages.

We also need a data access layer DAL, we need to build a folder.

IX. Add DAL folder

Build another BLL, and everything that logically relates to the data is built in there. Business Logic Layer BLL

X. Business Logic Layer BLL

It is business logic to verify that data exists.

SqlHelper works with databases, so put SqlHelper in the data access layer DAL.

Eleven, SqlHelper into the data access layer DAL

The next thing I want to do is manipulate the table TblStudent, and I may add, delete, check, and change various operations to this table. So, I create a class that operates on the TblStudent table. It is DAL for data access layer, we add Dal after TblStudent.

XII. TblStudentDal

XIII. Data Access Layer Code

Creating another class is the business logic layer.

XIV. Service Logic Layer Code

XV. The interface layer adjusts the service logic layer, and the service logic layer adjusts the data access layer.

Do not directly adjust the interface layer data access layer, otherwise it will cause a lot of trouble. The purpose of the three layers is to have a clear division of labor and not affect each other.

*** Let's see how effective it is.

XVI. Effect after implementation

Keep in mind that the configuration file is with the UI layer. I'll write a case later and show you.

Here we use three layers of verification for user names and passwords.

XVII. Design a login interface

Then we have to determine the Sql statement, how to determine whether the user name exists, whether the password is correct?

Find the password based on the username entered by the user

If the password is found, the username exists; if the password does not exist, the username does not exist.

If you find the password, verify whether it is correct, you can determine whether the login is successful.

select CC_AutoId, CC_Loginpassword from T_Seats where CC_LoginId=@uid

2. write data access layer

What is the result of executing Sql statements?

How to return multiple columns of a record.

The data access layer returns an object. (Model required)

18. Write a good Model

19. Write the data access layer

The data access layer obtains basic information of the current user according to the user name.

3. Write business logic layer. The business logic layer in age auto-growth is a soy sauce.

There has to be something at the business logic level.

How to determine the method parameters and return values of the business logic layer is determined according to the requirements of the presentation layer (caller).

Twenty, write an enumeration

21. Write MD5

22. Write the business logic layer

*** We write interface layers

23. Write a good interface layer

Look at the results of ***.

24. *** Show effect

Next, we implement the function of changing passwords:

Changing the password is exactly the same as the requirement we wrote with ADO. The password change button was initially disabled. When successful, write down the login id and the change password button is available. When you click on it, a window pops up. This window is used to change passwords.

25. Write *** Forms

Twenty-six, write the second form

Think about how to do that?

After successful login start modify password button, remember the user id, have to write a static class. So what layer is this class written to? Next, determine the next Sql statement, first verify whether the new password is correct (regardless of Sql), verify the old password and Sql.

Before we do this, let's look at the specific writing of the next three layers.

UI → Presentation layer, data collection, and data display.

Bll → business logic layer, all logic judgment and processing related to business.

Dal → data access layer, only the operation of the database, the sql statement execution, return the corresponding results. (Any logical processing is generally not recommended.)

Model

As in the above question, whether the text box is empty or not, special symbols cannot be input, etc. should be placed in the business logic layer. The judgment is whether the extracted data is empty or not, and the text box itself is not empty.

I can write it in the interface layer, but I'm going to replace the wins form with a web page, and I'll have to write it again in the interface layer. If you write in the business logic layer, just write the interface layer code.

For example, the judgment of registered mailbox is all JS's credit, not the problem of business logic layer.

XXVII. JS judgment

XXVIII. Interface Layer Logic

Static classes in presentation layer

29. Pass the Id from the service logic layer

Thirty, interface layer code

Run it and see how it works now. The advantage of doing this is that you don't have to wait until you're done. No one is a god, so step by step writing, easy to find out the mistakes of their own code.

31. Show *** partial results

Modify password operation is to determine the first Sql statement execution process, thinking: two new password input is consistent, the old password is correct, and then modify the password. Sql statement is not needed to determine consistency, and we need to write Sql statement to determine whether the old password is correct. Sql statements are also written to modify passwords.

1. Sql statement to determine if old password is correct

autoId，oldpwd "select count(*) from T_Seats where cc_autoId=@autoid and cc_loginPassword=@pwd"

Next we write the data access layer, since we are still manipulating that table, we do not need to create a new class.

32. Data Access Layer Code

The password modification operation is also a Sql statement,

33. Data Access Layer-Modify Password Code

Now that we've written the code for the data access layer, let's start writing the code for the business logic layer.

34. Enumeration Used by Business Logic Layer

35. Codes in the Business Logic Layer

Thirty-six. Three-tier architecture

About "SQLHelper and three-tier implementation of Age self-increasing what is the difference" content introduced here, thank you for reading. If you want to know more about industry-related knowledge, you can pay attention to the industry information channel. Xiaobian will update different knowledge points for you every day.

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