Creating connection object
To create a connection we pass the connection
string as a parameter in connection object.
Dim
str As String
= "Data
Source=.;uid=sa;pwd=123;database=master"
Dim con As New
SqlConnection(str)
The above string defines the connection string which is used to connect the
database with the application.
DataAdapter
The DataAdapter is used to retrieve the data from the database and place that
data in DataSet.
Dim
str1 As String =
"SELECT * FROM logn"
Dim
cmd As New SqlCommand(str1, con)
Dim
da As New SqlDataAdapter(cmd)
Dim
ds As New DataSet()
da.Fill(ds, "logn")
DataColumn
The Datacolumn represents a schema of the column in data table and ColumnName
property is used to find the name of the column.
Dim
dc As DataColumn
For Each dc In
ds.Tables(0).Columns
Console.Write("{0,12}",
dc.ColumnName)
Next
Console.WriteLine("")
DataRow
DataRow represents a row of data in a data table.
Dim
dr As DataRow
For Each dr In
ds.Tables(0).Rows
Dim
i As Integer
For
i = 1 To ds.Tables(0).Columns.Count
Console.Write("{0,12}",
dr(i - 1))
Next i
Console.WriteLine("")
Now we create a database table and insert some values in this table. Table looks
like this.
create table logn
(
username
varchar(50),
password varchar(40)
)
go
insert into logn values('monu','mohan')
go
insert into logn values('Rohatash','rohit')
go
insert into logn values('Manoj','singh')
go
select * from logn;
The table looks like this.
OUTPUT
Table1.gif
For example
Imports
System.Data.SqlClient
Module Module1
Sub Main()
Dim str As String = "Data
Source=.;uid=sa;pwd=123;database=master"
Dim con As New SqlConnection(str)
Dim str1 As String = "SELECT *
FROM logn"
Dim cmd As New SqlCommand(str1,
con)
Dim da As New SqlDataAdapter(cmd)
Dim ds As New DataSet()
da.Fill(ds,
"logn")
Dim dc As DataColumn
For Each dc
In ds.Tables(0).Columns
Console.Write("{0,12}",
dc.ColumnName)
Next
Console.WriteLine("")
Dim dr As DataRow
For Each dr
In ds.Tables(0).Rows
Dim i As Integer
For i = 1 To
ds.Tables(0).Columns.Count
Console.Write("{0,12}",
dr(i - 1))
Next i
Console.WriteLine("")
Next
End Sub
End Module
OUTPUT
