How to connect to the database in vb
In VB, connecting to the database is usually achieved using the two technologies ADO (ActiveX Data Objects) or DAO (Data Access Objects): 1. Introducing the ADO library; 2. Creating the ADO connection object; 3. Configuration Connection string; 4. Open the connection; 5. Execute the SQL statement; 6. Process the query results; 7. Close the connection.
In VB, connecting to the database is usually implemented using the two technologies ADO (ActiveX Data Objects) or DAO (Data Access Objects). The following is a set of sample codes for connecting to a database using ADO:
' 引入 ADO 库
Imports System.Data.OleDb
' 创建 ADO 连接对象
Dim conn As New OleDbConnection()
' 配置连接字符串
Dim connectionString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=<database path>"
' 打开连接
conn.ConnectionString = connectionString
conn.Open()
' 执行 SQL 语句
Dim cmd As New OleDbCommand("SELECT * FROM <table name>", conn)
Dim reader As OleDbDataReader = cmd.ExecuteReader()
' 处理查询结果
While reader.Read()
Console.WriteLine(reader("column1").ToString())
End While
' 关闭连接
conn.Close()In the above example In the code, the OleDbConnection class represents an ADO connection object, which can use the connection string to configure database connection information. The connection string contains important information such as the data provider, data source, and other connection parameters.
By creating OleDbCommand objects and setting corresponding SQL query statements, parameters and other properties, you can perform various database operations, such as query, insert, update and delete, etc.
In ADO, you can also use classes such as OleDbDataAdapter and DataSet for batch processing and caching of data, thereby improving the efficiency and performance of data access.
It should be noted that in actual development, in order to ensure the reliability and security of the code, it is not only necessary to correctly configure the connection string and parameters, but also to perform necessary error handling and exception handling to prevent accidents situation occurs.
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