protected static void FixColumnMeta(ValueExpression valEx, ColumnExpression colEx)
 {
     if (valEx != null && colEx != null)
     {
         valEx.ColumnMeta = colEx.Column.Meta;
     }
 }
 public override void Visit(ColumnExpression e)
 {
     _expression.Column = e;
 }
 public virtual void Visit(ColumnExpression e)
 {
     if (String.IsNullOrWhiteSpace(e.Column.Table.Alias))
     {
         _sql.Append(e.Column.Meta.ColumnName);
     }
     else
     {
         _sql.AppendFormat("{0}.{1}", e.Column.Table.Alias, e.Column.Meta.ColumnName);
     }
 }
 public virtual void Visit(ColumnExpression e)
 {
     throw new NotSupportedException();
 }