ASP.NET- database connectivity


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ASP.NET- database connectivity

  1. 1. – Database connectivity
  2. 2. How to connect an application with Database ConnectionString • The database connection information is stored in the web.config file as a ConnectionString tag. • Web.config is a xml file which is used to store application wide settings and constants • The ConnectionString has two main attributes – Name – this holds a name for the connectionstring with which a particular connectionstring is identified, useful when using multiple databases – ConnectionString – this holds the actual connection data
  3. 3. The ConnectionString attribute Database Host User Id Database name Password
  4. 4. Getting the connection information from within the application The connection string added in the web.config can be obtained from anywhere within the application using the following line of code ConnectionString name as given in the web.config For connecting to the database from an application we use the following inbuilt classes of the .net framework • sqlCommand object • sqlConnection object • sqlDataReader / sqlDataAdapter object
  5. 5. Creating and initializing the sqlCommand object The following lines of code creates an sqlCommand object and initializes it Name of the stored procedure passed as an argument Setting the command type property as stored procedure, the other commandtypes are text(for inline queries) and table direct Setting the commandName property to the passed in stored procedure name The above function takes the name of a stored procedure as parameter and returns a sqlCommand object whose commandtype is set as stored procedure and commandText is set as the name of the stored procedure
  6. 6. Interacting with the database The following lines of code connects with the database and runs the query in the commandText property of the sqlCommand object in the database property of the sqlCommand object The sqlCommand object is passed as an argument to the function sqlConnection object is initialized with the data in the connectionstring sqlDataAdapter object is initialized for the sqlCommand object Interacts with the database and returns the resulting dataset A new dataset variable is initialized for holding the returning data from the database (if any)
  7. 7. Interacting with the database • sqlDataReader object can also be used to interact with the database but it allows only one way communication, that is, read from the database, while sqlDataAdapter object allows writing to as well as reading from the database • The data read from the database is stored in the dataset object and returned Retrieving data from the dataset object A dataset object is a collection of datatable objects, datatables contain datarows and columns just as it will appear in a database table For eg. Suppose the dataset returned by a certain database interaction is as follows Id Name 10 Ab 11 cd class Subject v Maths x English Table 1 Table 2 ds
  8. 8. Retrieving data from the dataset object • The data in the second column of the first row in table 1 can be retrieved as – ds.Tables(0).rows(0)(1) or ds.Tables(0).rows(0)(“Name”) • Similarly the data in the second column of the second row in table 2 can be retrieved as – ds.Tables(1).rows(1)(1) or ds.Tables(1).rows(1)(“Subject”) Id Name 10 Ab 11 cd class Subject v Maths x English Table 1 Table 2
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