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Protected Function Database_Exist() As Boolean

    m_cmd = New Npgsql.NpgsqlCommand
    m_cmd.CommandText = "SELECT COUNT(*) FROM pg_catalog.pg_database WHERE datname = :database_name"
    m_cmd.Connection = mPostGisCnn
    m_cmd.Parameters.Add(New Npgsql.NpgsqlParameter(":database_name", mNomBase))
    Return m_cmd.ExecuteScalar > 0
    m_cmd.Dispose()

End Function

Protected Function schema_exists(schemaname As String) As Boolean
    Dim ds As New DataSet

    m_cmd = New NpgsqlCommand
    m_cmd.Connection = mPostGisCnn
    m_cmd.CommandText = "SELECT schema_name FROM information_schema.schemata WHERE schema_name='" & schemaname & "';"
    m_da = New NpgsqlDataAdapter
    m_da.SelectCommand = m_cmd
    m_da.Fill(ds)

    m_da.Dispose()
    m_cmd.Dispose()

    If ds.Tables(0).Rows.Count > 0 Then
        Return True
    Else
        Return False
    End If
End Function

Protected Sub Create_schema(schemaname As String)
    If schema_exists(schemaname) Then
        Exit Sub
    End If
    If schemaname <> "public" Then
        m_cmd = New NpgsqlCommand
        m_cmd.Connection = mPostGisCnn

        m_cmd.CommandText = "CREATE SCHEMA " & schemaname & ";"
        m_cmd.ExecuteNonQuery()
    End If

End Sub
Protected Function table_exists(nomschema As String, nomtable As String) As Boolean
    Dim ds As New DataSet

    m_cmd = New NpgsqlCommand
    m_cmd.Connection = mPostGisCnn
    m_cmd.CommandText = "select table_name from information_schema.tables WHERE table_schema=:p AND table_name=:p1;"

    Dim p As New NpgsqlParameter("p", nomschema)
    m_cmd.Parameters.Add(p)

    Dim p1 As New NpgsqlParameter("p1", nomtable)
    m_cmd.Parameters.Add(p1)

    m_da = New NpgsqlDataAdapter
    m_da.SelectCommand = m_cmd


    m_da.Fill(ds)

    m_da.Dispose()
    m_cmd.Dispose()

    If ds.Tables(0).Rows.Count > 0 Then
        Return True
    Else
        Return False
    End If
End Function