VB.Net/Database ADO.net/SqlCommand Select
Содержание
Execute two queries together
<source lang="vbnet"> Imports System Imports System.Data Imports System.Data.SqlClient
public class MainClass
Shared Sub Main() Dim thisConnection As New SqlConnection("server=(local)\SQLEXPRESS;" & _ "integrated security=sspi;database=MyDatabase") "Sql Query 1 Dim sql1 As String ="SELECT FirstName FROM Employee; " "Sql Query 2 Dim sql2 As String ="SELECT LastName FROM Employee;" "Combine queries Dim sql As String = sql1 & sql2 "Create Command object Dim thisCommand As New SqlCommand _ (sql, thisConnection) Try " Open Connection thisConnection.Open() Console.WriteLine("Connection Opened") " Execute Query Dim thisReader As SqlDataReader = thisCommand.ExecuteReader()
Catch ex As SqlException " Display error Console.WriteLine("Error: " & ex.ToString()) Finally " Close Connection thisConnection.Close() Console.WriteLine("Connection Closed") End Try End Sub
End Class
</source>
Get data from "Select" command
<source lang="vbnet"> Imports System Imports System.Collections Imports System.Data Imports System.IO Imports System.Xml.Serialization Imports System.Windows.Forms Imports System.Data.SqlClient
Public Class MainClass
Shared Dim WithEvents con As SqlConnection Shared Sub Main() con = New SqlConnection("Server=(local)\SQLEXPRESS;Initial Catalog=MyDatabase;Integrated Security=SSPI") " Create the command object Dim str As String = "SELECT ID, FirstName, LastName FROM Employee" Dim cmd As New SqlCommand(str, con) Dim da As New SqlDataAdapter(cmd) Dim ds As New DataSet() da.Fill(ds, "Employee") Dim dc As DataColumn For Each dc In ds.Tables(0).Columns Console.Write("{0,15}", dc.ColumnName) Next Console.Write(vbCrLf) 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("{0,15}", dr(i - 1)) Next i Console.Write(vbCrLf) Next End Sub
End Class
</source>
Output data from "Select" command in a table format
<source lang="vbnet"> Imports System Imports System.Collections Imports System.Data Imports System.IO Imports System.Xml.Serialization Imports System.Windows.Forms Imports System.Data.SqlClient
Public Class MainClass
Shared Dim WithEvents con As SqlConnection Shared Sub Main() con = New SqlConnection("Server=(local)\SQLEXPRESS;Initial Catalog=MyDatabase;Integrated Security=SSPI") " Create the command object Dim str As String = "SELECT ID, FirstName, LastName FROM Employee" Dim cmd As New SqlCommand(str, con) Dim da As New SqlDataAdapter(cmd) Dim ds As New DataSet() da.Fill(ds, "Employee") Dim dc As DataColumn For Each dc In ds.Tables(0).Columns Console.Write("{0,15}", dc.ColumnName) Next Console.Write(vbCrLf) 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("{0,15}", dr(i - 1)) Next i Console.Write(vbCrLf) Next End Sub
End Class
</source>
Read the result sets from two "select" command
<source lang="vbnet"> Imports System Imports System.Data Imports System.Data.SqlClient
public class MainClass
Shared Sub Main() Dim thisConnection As New SqlConnection("server=(local)\SQLEXPRESS;" & _ "integrated security=sspi;database=MyDatabase") "Sql Query 1 Dim sql1 As String ="SELECT FirstName, LastName FROM Employee; " "Sql Query 2 Dim sql2 As String ="SELECT LastName, FirstName FROM Employee;" "Combine queries Dim sql As String = sql1 & sql2 "Create Command object Dim thisCommand As New SqlCommand _ (sql, thisConnection) Try " Open Connection thisConnection.Open() Console.WriteLine("Connection Opened") " Execute Query Dim thisReader As SqlDataReader = thisCommand.ExecuteReader() " Loop through result sets Do " Fetch Data While (thisReader.Read()) Console.WriteLine("{0} | {1}", _ thisReader(0), _ thisReader(1)) End While Console.WriteLine("".PadLeft(60, "=")) Loop While (thisReader.NextResult())
"Close DataReader thisReader.Close() Catch ex As SqlException " Display error Console.WriteLine("Error: " & ex.ToString()) Finally " Close Connection thisConnection.Close() Console.WriteLine("Connection Closed") End Try End Sub
End Class
</source>
SqlDataAdapter: "select" command and the connection string
<source lang="vbnet"> Imports System Imports System.Xml Imports System.Xml.Schema Imports System.IO Imports System.Data.SqlClient Imports System.Collections Imports System.Data
Public Class MainClass
Shared Sub Main() Dim da As New SqlDataAdapter( _ "SELECT ID, FirstName, LastName FROM Employee", _ "Server=(local)\SQLEXPRESS;Initial Catalog=MyDatabase;Integrated Security=SSPI") Dim ds As New DataSet("Employee") da.FillSchema(ds, SchemaType.Source) ds.ReadXml("Employee.xml") Dim Table As DataTable = ds.Tables(0) Dim numCols As Integer = Table.Columns.Count Dim Row As DataRow For Each Row In Table.Rows Dim i As Integer For i = 0 To numCols - 1 Console.WriteLine(Table.Columns(i).ColumnName & " = " & Row(i)) Next Console.WriteLine() Next End Sub
End Class
</source>
Use SqlDataReader to read result set from "select" command
<source lang="vbnet"> Imports System Imports System.Data Imports System.Data.SqlClient public class MainClass
Shared Sub Main() Dim thisConnection As New SqlConnection("server=(local)\SQLEXPRESS;" & _ "integrated security=sspi;database=MyDatabase") "Create Command object Dim thisCommand As New SqlCommand _ ("SELECT FirstName, LastName FROM Employee",thisConnection) Try " Open Connection thisConnection.Open() Console.WriteLine("Connection Opened") " Execute Query Dim thisReader As SqlDataReader = thisCommand.ExecuteReader() While (thisReader.Read()) Console.WriteLine("Employee: {0} {1}", _ thisReader.GetValue(0), thisReader.GetValue(1)) End While Catch ex As SqlException " Display error Console.WriteLine("Error: " & ex.ToString()) Finally " Close Connection thisConnection.Close() Console.WriteLine("Connection Closed") End Try End Sub
End Class
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