A summary of the problem of database connection

The relationship of 1.odbc,oledb,ado,adox:
ODBC: Used database communication standards
OLE DB: In all the object-oriented trends, MS intends to use it instead of ODBC.
OLE DB is divided into two types: direct OLE DB and ODBC-oriented OLE DB, the latter architecture on ODBC, which
Databases that do not have their own OLE DB providers can also use the features of OLE DB.
ADO: is actually just an application-level interface that uses OLE DB to communicate with the database.
ADOX: The security of ADO, maintenance (such as: Create a database) has been extended.

2. Connect to the database with ODBC:
There are three types of DSNs available in ODBC, and the difference is simple: a user DSN can only be used for this user. The difference between a System DSN and a file DSN is only that the connection information is stored in a different location: The System DSN is stored in an ODBC storage area, and the file DSN is placed in a text file.
The way they are created is not said.
When using them in ASP, the following are written:
A.sql Server:
Using the system dsn:connstr= "DSN=DSNNAME;" Uid=xx; Pwd=xxx;database=dbname "
Use the document Dsn:connstr= "FILEDSN=XX; Uid=xx; Pwd=xxx;database=dbname "
You can also use a connection string (thereby eliminating the need to create a DSN):
Connstr= "Driver={sql SERVER}; Server=servername; Uid=xx; Pwd=xxx "
B.access:
Using the system dsn:connstr= "Dsn=dsnname"
(or for: connstr= "dsn=dsnname; Uid=xx; Pwd=xxx ")
Dsn:connstr= "Filedsn=xx" with file
You can also use a connection string (thereby eliminating the need to create a DSN):
Connstr= "Driver={microsoft Access DRIVER};D Bq=d:\abc\abc.mdb"

3. Connect the database with OLE DB:
A.sql Server:
Connstr= "PROVIDER=SQLOLEDB;
DATA Source=servername; Uid=xx; Pwd=xxx;database=dbname "
B.access:
Connstr= "Provicer=microsoft. JET. oledb.4.0;
DATA Source=c:\abc\abc.mdb "

4. Use UDL file:
A UDL file is a text file that holds database connection information, somewhat like a file DSN, but the UDL is for OLE DB (direct and ODBC-oriented).
How to create a UDL:
Right-click the desktop or Resource Manager-new-"Microsoft Data Connection"
The setup work should be more clear.
Use of UDL:
connstr= "File Name=e:\abc\abc.udl"