private string GenerateFunctionName(FieldFunctionType function)
        {
            switch (function)
            {
            case FieldFunctionType.Lower:
                return("lower");

            case FieldFunctionType.Upper:
                return("upper");

            case FieldFunctionType.Substring:
                return("substr");
            }
            throw new NotImplementedException($"Could not generate function {function.ToString()}");
        }
 public SqlFunctionExpression(FieldType type, SqlExpression body, FieldFunctionType function, params SqlExpression[] arguments) : base(type, body, arguments)
 {
     this.Function = function;
 }