Use c # To operate ACCESS databases

There is no Microsoft Access at hand. It is still easy to create a database.
First, reference C: \ Program Files \ Common Files \ System \ ado \ msadox. dll, which contains the ADOX namespace;
Then reference C: \ Program Files \ Common Files \ System \ ado \ msjro. dll, which contains the JRO namespace
Tips for SxS: for example, if the dll Import fails, manually import the com component as a. net Component and use vs.net to import it.

Using System;
Using System. IO;
Using ADOX; // The namespace contains the class (method) for creating ACCESS -- Solution ==> reference ==> add reference ==> find. dll
Using JRO; // The namespace contains the class (method) for compressing ACCESS)
Public class Access
...{
/** // Create an ACCESS database based on the specified file name
/// MdbPath: the absolute ACCESS path of the file to be created
Public void Create (string mdbPath)
...{
If (File. Exists (mdbPath) // check whether the database already Exists
...{
Throw new Exception ("the target database already exists and cannot be created ");
}
// You can add a password so that the created database can be opened only after the password is entered.
MdbPath = "Provider = Microsoft. Jet. OLEDB.4.0; Data Source =" + mdbPath;
// Create an instance of the CatalogClass object,
ADOX. CatalogClass cat = new ADOX. CatalogClass ();
// Use the Create method of the CatalogClass object to Create an ACCESS database
Cat. Create (mdbPath );
}
/*** // Compress and fix the ACCESS database. The mdbPath is the absolute path of the database.
Public void Compact (string mdbPath)
...{
If (! File. Exists (mdbPath) // check whether the database already Exists
...{
Throw new Exception ("the target database does not exist and cannot be compressed ");
}
// Declare the temporary database name
String temp = DateTime. Now. Year. ToString ();
Temp + = DateTime. Now. Month. ToString ();
Temp + = DateTime. Now. Day. ToString ();
Temp + = DateTime. Now. Hour. ToString ();
Temp + = DateTime. Now. Minute. ToString ();
Temp + = DateTime. Now. Second. ToString () + ". bak ";
Temp = mdbPath. Substring (0, mdbPath. LastIndexOf ("\") + 1) + temp;
// Define the connection string of the temporary database
Temp2 = "Provider = Microsoft. Jet. OLEDB.4.0; Data Source =" + temp;
// Define the connection string of the target database
MdbPath2 = "Provider = Microsoft. Jet. OLEDB.4.0; Data Source =" + mdbPath;
// Create an instance of the JetEngineClass object
JRO. JetEngineClass jt = new JRO. JetEngineClass ();
// Use the CompactDatabase method of the JetEngineClass object to compress and restore the database
Jt. CompactDatabase (mdbPath2, temp2 );
// Copy the temporary database to the target database (overwrite)
File. Copy (temp, mdbPath, true );
// Delete the temporary database
File. Delete (temp );
}

/** // Back up the database, mdb1, absolute path of the source database, and mdb2: absolute path of the target database
Public void Backup (string mdb1, string mdb2)
...{
If (! File. Exists (mdb1 ))
...{
Throw new Exception ("the source database does not exist ");
}
Try
...{
File. Copy (mdb1, mdb2, true );
}
Catch (IOException ixp)
...{
Throw new Exception (ixp. ToString ());
}
}
/** // Restore the database. mdb1 indicates the absolute path of the backup database, and mdb2 indicates the absolute path of the current database.
Public void Recover (string mdb1, string mdb2)
...{
If (! File. Exists (mdb1 ))
...{
Throw new Exception ("the backup database does not exist ");
}
Try
...{
File. Copy (mdb1, mdb2, true );
}
Catch (IOException ixp)
...{
Throw new Exception (ixp. ToString ());
}
}
}
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In BETA2 ,. NET provides the following NAMESPACE:
System. Data Namespace
System. Data. OleDb (it is different from BETA1, so it is definitely not possible to run the program in BETA1 to BETA2)

If I want to clarify these things, I don't think I can do it, so I want to use some specific programs to demonstrate the most basic database operations (SELECT, UPDATE, DELETE, INSERT, etc, other things need to be learned by friends!

To operate a database, you must first open the database. The following uses an ACCESS database as an example to illustrate how to open a database connection! Here we need to use: System. Data. OleDb. OleDbConnection class! (If you operate SQL databases, we 'd better use the System. Data. SqlClient. SqlConnection class)

I will first write my own program:

Using System. Data
Using System. Data. OleDb

Public OleDbConnection getConn ()
{
String connstr = "Provider = Microsoft. Jet. OLEDB.4.0; Data Source = F :\\ web \ notesbook \ class \ leavenotes. mdb ";
OleDbConnection tempconn = new OleDbConnection (connstr );
Return (tempconn );
}

I believe that anyone who has used ADO can understand it! First, we define a variable of the String type, which stores the connection String that we connect to the database, and then define a System. data. oleDb. oleDbConnection type object, instantiate it, and finally return this object! It should be noted that I didn't put the statement: tempconn. Open (); into this function. The reason is that I will explain it later. Here I just want to remind you!

Through the above function, we have obtained a Connection object similar to the Connection object in ADO! The following is the specific database operation!

Before specific operations, I think it is necessary to first understand the following two classes:
System. Data. OleDb. OleDbDataAdapter
System. Data. OleDb. OleDbDataReader

System. Data. OleDb. OleDbDataAdapter: You can directly contact DataSet and operate the Data source. It is more powerful and consumes System resources!
System. data. oleDb. oleDbDataReader: It is similar to the read-only forward record set in ADO. It is most commonly used when only the data needs to be read and displayed in sequence, compared with System. data. oleDb. oleDbDataAdapter is short of system resources! In fact, OleDbDataReader can implement all functions, but we should try to use the former from the perspective of resource usage! However, some functions can be implemented only by using OleDbDataAdapter!