- ADO.NET technology
ADO.NET is a class library in .NET Framework. It is a new object-oriented class library developed on the basis of ADO technology. It is a standard service for ASP, NET and Windows Forms applications to access various data sources. Its purpose is to In order to be able to manipulate data in NET programs. ADO.NET contains a variety of classes related to data access. Using ADO.NET will shield a large number of complex data operations in the database, and is more suitable for large-scale application environments such as distributed and Internet than ADO. In application development, the basic operations of the database can be completed relatively simply, and the simultaneous access by multiple people is also more scalable.
ADO.NET consists of two core components, Dataset and .NET Framework data provider.
(1) Dataset object
Specifically designed for data access independent of any data source, a Dataset object is a memory-resident representation of data that provides a consistent relational programming model regardless of the data source it contains. Since the Dataset object is an in-memory cache of data retrieved from the database, it supports access to data in a disconnected state.
A Dataset object contains one or more DataTable objects, which have the ability to store multiple table data and relationships between tables. These tables are stored in the DataTable object, and the relationship between the tables is represented by the DataRelation object.
DataTable is defined in the System.Data namespace and represents a data table that resides in memory. It contains a set of columns represented by the DataColumn (data column) set and a constraint set represented by the Constraint (data constraint) set. These columns and The constraints together define the logical structure of the table. In addition, the DataTable also contains the collection of rows represented by the DataRow (data row) collection, and the DataRow collection contains the data in the table.
A DataRelation object associates a row in one DataTable with a row in another DataTable, the relationship is similar to the join path between the primary key column and the foreign key column in the database, the matching columns of the two data tables in the collection, can be in the Dataset Navigating from one table to another, the basic elements of a DataRelation are the name of the relationship, the name of the related tables, and the related columns in each table. When a relationship is added to a DataRelation collection, if changes are made to related column values, the relationship may choose to add UniqueKeyConstraint (unique key constraint) and ForeinKeyConstraint (foreign key constraint) to enforce integrity constraints
(2) NET data provider
Another core element of ADO.NET is the .NET data provider, whose purpose is to implement data manipulation and its fast access to data, and for this purpose contains several objects: Connection, Command, DataReader, DataAdapter.
Connection objects provide connections to a variety of different types of data sources.
The Command object can access database commands for returning data, modifying data, running stored procedures, and sending or retrieving parameter information. In the optional Parameters collection it contains, parameters of database commands or stored procedures can be defined.
DataReader objects provide high-performance data streaming from data sources for fast data access. The Data-Adapter provides a bridge to connect the Dataset object and the data source. Use the SelectCcommand object to execute the SQL. command in the data source in order to load the data into the Dataset. At the same time, you can use the InsertCommand UpdateCommand or DeleteCommand object to return the changes of the data in the Dataset to the data. in the source.
- Database access
This project uses MySQ1. The database, MySQ1, is an open source relational database with a data warehouse that supports 0 million records. It is suitable for all platforms, open source software, fast version update, excellent performance and Advantages such as cheap price.
The main database access method used in database access is ADO.NET. The steps to create a database access link based on ADO.NET technology are:
②Create a database link string, which contains the database server name, user name, password and database name and other information;
③ Send the SQ1 command to the database;
①Return the command execution result and close the database link;
⑤ The user processes the returned result; displays the result on the user interface.
- Local monitoring interface display
Install the application software in the C/S mode on the local monitoring computer, open the software and enter the software login interface as shown in Figure 1.
After entering the user name and correct password on the login interface, enter the home page of the monitoring system of the system, and then monitor through the menu at the top of the interface.
The monitoring interface of the monitoring system for the inverter, fault information and fault diagnosis, the inverter monitoring interface displays various parameters and operating status of the inverter. When a fault occurs, the corresponding green light turns red and the whistle alarms. . The fault information interface shows the faults in the current system, which can be displayed more clearly through fault diagnosis, and some corresponding solutions can be provided.
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