dynamic query builder

gistfile1.cs

public class DynamicQueryBuilder : DynamicObject
    {
        private readonly string m_tableName;
        private string internalQuery;

        public DynamicQueryBuilder(string tableName)
        {
            m_tableName = tableName;
        }

        public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
        {
            var operation = binder.Name;
            if (operation.Equals("All"))
            {
                result = All();
                return true;
            }
            if (operation.StartsWith("FindAllBy"))
            {
                var column = operation.Substring("FindAllBy".Length);
                if (binder.CallInfo.ArgumentCount != 1)
                {
                    throw new ArgumentException("'FindAllBy' must be call with a single argument");
                }

                var argument = args.Single();
                internalQuery = FindAllBy(column, Helper.WrapWithQuotes(argument));
                result = this;
                return true;
            }
            var prefix = string.IsNullOrEmpty(internalQuery) ? string.Empty : " ";
            if (operation.Equals("Select"))
            {
                internalQuery += prefix + Select(args.Select(e => e.ToString()));
                result = this;
                return true;
            }
            if (operation.Equals("Where"))
            {
                if (binder.CallInfo.ArgumentCount < 1)
                {
                    throw new ArgumentException("'Where' must be call with at least argument");
                }
                internalQuery += prefix + Where(args);
                result = this;
                return true;
            }

            throw new ArgumentException("Unsupported operation: " + operation);
        }

        public override bool TryGetMember(GetMemberBinder binder, out object result)
        {
            result = new DynamicColumn(binder.Name);
            return true;
        }

        public override string ToString()
        {
            return internalQuery;
        }

        string Select(IEnumerable<string> columns)
        {

            return string.Format("Select {0} from {1}", string.Join(", ", columns), m_tableName);
        }

        string Where(params object[] expressions)
        {
            return string.Format("Where {0}", string.Join(" and ",expressions.Select(e=> e.ToString())));
        }

        string FindAllBy(string column, string value)
        {
            return string.Format("Select * from {0} Where {1} = {2}", m_tableName, column, value);
        }

        string All()
        {
            return "Select * from " + m_tableName;
        }
    }

static internal class Helper
    {
        static bool IsNumber(object argument)
        {
            return argument is int || argument is decimal || argument is float;
        }

        public static string WrapWithQuotes(object argument)
        {
            if (IsNumber(argument))
            {
                return argument.ToString();
            }
            return "\'" + argument.ToString().Replace("'", "''") + "'";//escaping quotes
        }
    }

public class DynamicColumn
    {
        public string Column { get; private set; }

        public DynamicColumn(string column)
        {
            Column = column;
        }

        public static string operator ==(DynamicColumn column, DynamicColumn foo2)
        {
            return column == foo2.Column;
        }

        public static string operator !=(DynamicColumn column, DynamicColumn foo2)
        {
            return (column != foo2.Column);
        }

        public static string operator !=(DynamicColumn foo1, object foo2)
        {
            return string.Format("{0} != {1}", foo1.Column, Helper.WrapWithQuotes(foo2));
        }

        public static string operator ==(DynamicColumn foo1, object foo2)
        {
            return string.Format("{0} = {1}", foo1.Column, Helper.WrapWithQuotes(foo2));

        }

        public bool Equals(DynamicColumn other)
        {
            if (ReferenceEquals(null, other)) return false;
            if (ReferenceEquals(this, other)) return true;
            return Equals(other.Column, Column);
        }

        public override bool Equals(object obj)
        {
            if (ReferenceEquals(null, obj)) return false;
            if (ReferenceEquals(this, obj)) return true;
            if (obj.GetType() != typeof(DynamicColumn)) return false;
            return Equals((DynamicColumn)obj);
        }

        public override int GetHashCode()
        {
            return (Column != null ? Column.GetHashCode() : 0);
        }

        public override string ToString()
        {
            return Column;
        }
    }