SQL connection string

Source: Internet
Author: User
Tags how to connect to sql server connection reset
The SQL Server. NET Data Provider connection string contains a set of attribute name/value pairs. Each attribute/value pair is separated by a semicolon. PropertyName1 = Value1; PropertyName2 = Value2; PropertyName3 = Value3 ;..... similarly, the connection string must contain the SQL Server instance name: Data Source = ServerName; use the local SQL Server (localhost). If you want to run it on a remote Server, the correct server should be assigned to the Data Source attribute in the example object. In addition, you must specify either of the two supported authentication methods (Windows Authentication and SQL Server Authentication. Windows Authentication uses Windows login user identity to connect to the database, and SQL authentication requires that the SQL Server user ID and password be explicitly specified. To use Windows authentication, you must include the Integrated Security attribute in the connection string: Data Source = ServerName; Integrated Security = True; by default, the Integrated Security attribute is False, this means Windows authentication is disabled. If the value of this attribute is not explicitly set to True, the connection uses SQL Server Authentication. Therefore, the SQL Server user ID and password must be provided. The Integrated Security attribute can recognize other values only SSPI (Security Support Provider Interface, Security Support Provider Interface ). all Windows NT operating systems, including Windows NT 4.0, 2000, and XP, support SSPI. It is the only interface that can be used for Windows authentication. It is equivalent to setting the value of Integrated Security to True. In Windows Authentication mode, SQL Server uses the Windows security subsystem to verify the validity of user connections. Even if the user ID and password are explicitly specified, SQL Server does not check the user ID and password in the connection string. Because only Windows NT, 2000, and XP support SSPI, if you are using these operating systems, you can only use Windows integrated security policies to connect to SQL Server. No matter which operating system is used, when using SQL Server Authentication, you must specify the User ID and password in the connection string: Data Source = ServerName; User ID = donaldx; password = unbreakable by default, SQL Server.. NET Data Provider connects to the default database of the specified user. When creating a user in the database, you can set the default database of the user. In addition, you can change your default database at any time. For example, the default database of the system administrator is master. If you want to connect to different databases, you should specify the Database Name: Data Source = ServerName; Integrated Security = SSPI; Initial Catalog = Northwind each authentication has its advantages and disadvantages. Windows Authentication uses a single user information library source. Therefore, you do not need to configure users for database access separately. The connection string does not contain the user ID and password, which eliminates the risk of exposing the user ID and password to unauthorized users. Users and their roles can be managed in Active Directory without explicitly configuring their properties in SQL Server. The disadvantage of Windows authentication is that it requires the user to connect to SQL Server through the Secure Channel supported by the Windows security subsystem. If the application needs to connect to SQL Server through an insecure network (such as the Internet), Windows authentication will not work. In addition, this authentication method also partially transfers the responsibility for managing database access control from the DBA to the system administrator, which may be a problem in the identified environment. In general, some aspects will be enhanced to use Windows authentication when designing common applications. Most companies' databases reside on robust Windows server operating systems that support Windows authentication. The separation of the data access layer and the data presentation layer also promotes the application of data access code encapsulated in the middle layer component idea. The middle layer component usually runs in the internal network with a database server. In this design, you do not need to establish a database connection through an insecure channel. In addition, Web Services also greatly reduce the need to directly connect to databases in different domains. From: http://www.cnblogs.com/lanse777/archive/2007/03/28/691757.html database connectivity has developed into a standard aspect of application development. Database connection strings are now a standard prerequisite for each project. I found that in order to find the required syntax, I often need to copy the connection string from another application or perform a search. This is especially true when interacting with SQL Server because it has too many connection string options. Now let's take a look at the many aspects of the connection string. During Object Instantiation or establishment, the database connection string is passed to the necessary object through attributes or methods. The format of the connection string is a list of key/value parameter pairs divided by semicolons. List A contains an example in C # That describes how to connect to SQL Server by creating A SqlConnection object (the actual connection string is allocated through the ConnectionString attribute of the object ). List B contains the VB. NET version. List Astring cString = "Data Source = server; Initial Catalog = db; User ID = test; Password = test;"; SqlConnectionconn = new SqlConnection (); conn. connectionString = cString; conn. open (); List BDim cString As String cString = "Data Source = server; Initial Catalog = db; User ID = test; Password = test; "Dim conn As SqlConnection = New SqlConnection () conn. connectionString = cString conn. the Open () connection string specifies the database server and database, and the users required to access the database. Name and password. However, this format does not apply to all database interactions. It does have many available options, many of which have synonyms. With Data Source, Initial Catalog, User ID, Password, and other elements, the following options are available: application Name: the Name of the Application. If it is not specified, its value is. NET SqlClient Data Provider (Data Provider ). attachDBFilename/extended properties (extended attribute)/Initial File Name (Initial File Name): Name of the main File that can be connected to the database, including the full path Name. The database name must be specified with the keyword database. Connect Timeout (Connection Timeout)/Connection Timeout (Connection Timeout): the length of time (in seconds) for a Connection to the server to wait before termination. The default value is 15. Connection Lifetime: when a Connection is returned to the Connection pool, its creation time is compared with the current time. If the time span exceeds the validity period of the connection, the connection will be canceled. The default value is 0. Connection Reset: Indicates whether a Connection is Reset when it is removed from the Connection pool. A pseudo-valid server does not need to run back and forth after obtaining a connection. The default value is true. Current Language: the name of the SQL Server Language record. Data Source/Server/Address/Addr/Network Address: The name or Network Address of the SQL Server instance. Encrypt (encryption): When the value is true, if an authorization certificate is installed on the Server, SQL Server uses SSL encryption for all data transmitted between the client and the Server. The accepted values include true, false, yes, and no ). Enlist: indicates whether the connection pool program automatically registers the connection in the current transaction context of the Creation thread. The default value is true. Database/Initial Catalog: name of the Database. Integrated Security/Trusted Connection: Indicates whether Windows authentication is used to connect to the database. It can be set to "true", "false", or "true-to-peer" sspi. Its default value is "false. Max Pool Size (maximum capacity of the Connection Pool): the maximum number of connections allowed by the connection Pool. The default value is 100. Min Pool Size (minimum capacity of the Connection Pool): the minimum number of connections allowed by the connection Pool. The default value is 0. Network Library/Net: The Network Library used to establish a connection to an SQL Server instance. Supported values include dbnmpntw (Named Pipes), dbmsrpcn (Multiprotocol/RPC), dbmsvinn (Banyan Vines), dbmsspxn (IPX/SPX), and dbmssocn (TCP/IP ). The dynamic Connection Library of the Protocol must be installed to an appropriate connection. The default value is TCP/IP. Packet Size: the Size of the network Packet used to communicate with the database. The default value is 8192. Password/Pwd: Password corresponding to the account name. Persist Security Info: used to determine whether Security information is available once a connection is established. If the value is true, sensitive data such as the user name and password is available, and false data is unavailable. Resetting the connection string will reconfigure the values of all connection strings, including passwords. The default value is false. Pooling: determines whether to use the connection pool. If the value is true, the connection will be obtained from the appropriate connection pool, or, if necessary, the connection will be created and then added to the appropriate connection pool. The default value is true. User ID: the account name used to log on to the database. Workstation ID: the name of the Workstation connected to SQL Server. The default value is the name of the local computer. This article from the CSDN blog, reproduced please indicate the source: http://blog.csdn.net/realduke2000/archive/2008/06/13/2543899.aspx

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