Connecting to a Database

This chapter describes how client applications connect to Sybase Adaptive Server Enterprise using the ASE OLE DB Provider.

Introduction to connections

Any client application that uses ASE must establish a connection to that server before any work can be done. The connection forms a channel through which all activity from the client application takes place. For example, your user ID determines permissions to carry out actions on the database--and the database server has your user ID because it is part of the request to establish a connection.

The ASE OLE DB Provider uses connection information included in the call from the client application, perhaps together with information held on disk in an initialization file, to locate and connect to an ASE server running the required database.

How connection parameters work

When an application connects to a database, it uses a set of connection parameters to define the connection. Connection parameters include information such as the server name, the database name, and a user ID. A keyword-value pair (of the form parameter=value) specifies each connection parameter. For example, you specify the user ID connection parameter as follows:

User ID=sa

Passing connection parameters as connection strings

Connection parameters are assembled into a connection string, in which a semicolon separates each connection parameter, as shown:

parameter1=value1;parameter2=value2;...

The connection string is then passed to the ASE OLE DB Provider.

Using connection parameters

Following is a list of connection parameters that can be supplied to the ASE OLE DB Provider.

Table 2-1: Connection parameters

Property names	Description	Required	Default value
User ID, UserID, UID	A case-sensitive user ID required to connect to the ASE server.	Yes	None
PWD, Password	A case-sensitive password to connect to the ASE server.	No, if the user name does not require a password	Empty
Data Source	The Data Source you want to connect in Server:Port format.	No, if server and port are specified	Empty
Server	The name or the IP address of the ASE server.	No, if data source is specified	Empty
Port	The port number of ASE server.	No, if data source is specified	Empty
Initial Catalog, Database	The database to which you want to connect.	No	Empty
UseCursor	Specifies whether cursors are to be used by the driver. 0 indicates do not use cursors, and 1 indicates use cursors.	No	0
ApplicationName	The name ASE uses to identify the client application.	No	Empty
PacketSize	The number of bytes per network packet transferred between ASE and the client.	No	512
CharSet	The designated character set. The specified character set must be installed on the ASE server.	No	Empty
Language	The language in which ASE returns error messages.	No	Empty - ASE uses English by default.
Encryption	The designated encryption. Possible values: ssl.	No	Empty
TrustedFile	If encryption is set to ssl, this property should be set to the path to the Trusted File.	No	Empty
DSURL	The URL to the LDAP server	No	Empty
DSPrincipal	The user name used to authenticate on the LDAP server, if the LDAP server does not allow anonymous access. The Principal can be specified in the DSURL as well.	No	Empty
DSPassword	The password used to authenticate on the LDAP server, if the LDAP server does not allow anonymous access. The password can be specified in the DSURL as well.	No	Empty
DynamicPrepare	When set to 1, the driver sends SQLPrepare calls to ASE to compile/prepare. This can boost performance if you reuse the same query repeatedly.	No	0
LoginTimeOut	Number of seconds to wait for a login attempt before returning to the application. If set to 0, the timeout is disabled and a connection attempt waits for an indefinite period of time.	No	10
QuotedIdentifier	Specifies if ASE treats character strings enclosed in double quotes as identifiers. 0 indicates do not enable quoted identifiers, 1 indicates enable quoted identifiers.	No	0
EncryptedPassword	Specifies if password encryption is enabled. 0 indicates password encryption is disabled, 1 indicates password encryption is enabled.	No	0
BufferPoolSize	Keeps the input / output buffers in pool. When large results will occur, increase this value to boost performance.	No	20
CRC	By default, the driver returns the total records updated when multiple update statements are executed in a stored procedure. This count will also include all updates happening as part of the triggers set on an update or an insert. Set this property to 0 if you want the driver to return only the last update count.	No	1
ClientHostName	The name of the client host passed in the login record to the server.	No	Empty
ClientHostProc	The identity of the client process on this host machine passed in the login record to the server.	No	Empty
TextSize	The maximum size of binary or text data that will be sent over the wire.	No	Empty. ASE default is 32K.
AnsiNull	Strict compliance where you cannot use "= NULL." Instead, you must use "IsNull."	No	1

Connecting from ADO

Microsoft ActiveX Data Objects (ADO) is an object-oriented programming interface. In ADO, the Connection object represents a unique session with a data source. You can use the following Connection object features to initiate a connection:

The Provider property holds the name of the provider. If you do not supply a Provider name, ADO uses the MSDASQL provider.
The ConnectionString property holds a connection string. This property holds an ASE connection string. You can supply OLE DB data source names, or explicit UserID, Password, DatabaseName, and other parameters, just as in other connection strings.
The Open method uses the connection objects to initiate a connection.

Example

The following Visual Basic code uses the connection objects to initiate an OLE DB connection to ASE:

' Declare the connection object
Dim myConn as New ADODB.Connection
myConn.Provider = "ASEOLEDB"
myConn.ConnectionString ="Data Source=MANGO:5000; User ID=sa"
myConn.Open


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