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VB.net Check if a column exists in a SQL Table

Posted on 2014-11-11
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Last Modified: 2014-11-11
Hi
What VB.net code would I use to check if a column exists in a SQL table?
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Question by:Murray Brown
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5 Comments
 
LVL 2

Expert Comment

by:Pratik Makwana
ID: 40434702
This function is check if column is exist or not.....

Dim oField ' As ADODB.Field
      Dim oRecordset ' As ADODB.Recordset
      Dim oConn ' As ADODB.Connection
      Dim nameToCheck
      Dim nameExists
      
      ' The column name you're looking for
      nameToCheck = "ID"
      nameExists = false
      
      ' Create connection
      Set oConn = Server.CreateObject("ADODB.Connection")
      oConn.Open "YourConnectionString"
      
      Set oRecordset = oConn.Execute("SELECT * FROM YourTable")
      
      For Each oField In oRecordset.Fields
            If oField.Name = nameToCheck Then
                  nameExists = True
                  Exit For
            End If
      Next
      
      oRecordset.Close()
      oConn.Close()
      Set oConn = Nothing
      Set oRecordset = Nothing
      
      Response.Write("Field " & nameToCheck & " found: " & nameExists)
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LVL 70

Accepted Solution

by:
Éric Moreau earned 2000 total points
ID: 40434836
It is better not to use ADODB in a .Net application!

Do you already have the structure in a DataSet/DataTable?

If you want to go pure SQL, you could use this:
SELECT T.name AS TableName, C.name AS ColumnName 
FROM sys.tables AS T
INNER JOIN sys.columns AS C
ON C.object_id = T.object_id
WHERE T.name = 'RefPrefix'
AND C.name = 'Code2'

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0
 
LVL 17

Expert Comment

by:OriNetworks
ID: 40435049
I think Eric has the best answer here where t.name is the table name you are checking and C.name is the column name you are checking for. If the column exists, it will return one row. If it does not exist, no rows will be returned.
0
 
LVL 28

Expert Comment

by:Ark
ID: 40436608
    Public Shared Function ColumnExists(ByVal tableName As String,
                                        ByVal columnName As String,
                                        ByVal conn As SqlClient.SqlConnection) As Boolean
        Dim strSQL As String = "SELECT COUNT(*) FROM information_schema.columns " & _
                               "WHERE table_schema = 'dbo' " & _
                               "AND table_name = '" & tableName & "'" & _
                               "AND column_name = '" & columnName & "';"
        Using cmd As New SqlClient.SqlCommand(strSQL, conn)
            Return CBool(cmd.ExecuteScalar)
        End Using
    End Function

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Dim bExists As Boolean
Using conn As New SqlClent.SqlConnection(YourConnectionStringHere)
    conn.Open()
    bExists = ColumnExists(YourTableName, YourColumnName, conn)
    conn.Close()
End Using

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Author Closing Comment

by:Murray Brown
ID: 40436653
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