Problem with using substring

Question

I have a query method that works, it brings the information from the database, however I am trying to use substring to get a part of a certain value from a table, I am using Iqueryable, but informs that it can not convert string to int, could anyone instruct me to fix the problem, I'm using nhibernate. Follow the code below:

 

 This is my select:

select fo.year_exercise_ctx, fo.cod_font_group, fo.cod_fonte, fo.name_fonte,
       ne.idt_document, ne.year_document, ne.cod_ug, ne.cod_document, substr (ne.cod_ranking, 54,4)
  from lag4_es_2019.spa_fonte fo
  left join lag4_es_2019.spe_ne ne
     on fo.cod_group_fonte = substr (ne.cod_ranking, 54,1) and fo.cod_fonte = substr (ne.cod_ranking, 56,2)
  where fo.cod_font_font not in (0) and fo.cod_font not in (00)
     order by fo.cod_group_fonte, fo_cod_fonte, ne.cod_ug, ne.cod_document;

 My code:

public static IQueryable ListAll
        {
            ISessionFactory session = FluentHelper.GetSessionFactory (EnumDatabase.MsSqlSiplag);
            IQueryable
                .CreateCriteria  ("ne")
                .List  (). AsQueryable ()
                .Select ((i, x) => new {x, str = i.CodSubscription.Substring ("54,4", x)});



            var aa = criterion; //Criterio.List (). ToList ();
            return null;
        }

I tried to implement the condition without success.

public static IQueryable ListAll()
        {
            ISessionFactory session = FluentHelper.GetSessionFactory(EnumDatabase.MsSqlLag);
            IQueryable criteria = session.OpenSession()
                .CreateCriteria("ne")

                .List().AsQueryable()
                .Where(g => g.Codranking.Contains(g.Codranking.Substring(54, 4), g.Codranking.Substring(54, 1), g.Codranking.Substring(56, 2)));
                //.Select((i, x)=> new {x, str = i.CodClassificacao.Substring("54,4", x) });

            var aa = criteria; //criterio.List().ToList();
            return null;
        }

 

using Domain.Lag.Domain;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Domain.Lag.DataAccess.DTO
{
    public class EmpenhoDTO
    {
        //public string CodEmpenho { get; set; }
        public virtual string CodClientCTX { get; set; }
        public virtual string IdtDocument { get; set; }
        public virtual string YearExerciseCTX { get; set; }
        public virtual string CodRanking { get; set; }
        public virtual string CodDocument { get; set; }
        public virtual string CodUg { get; set; }
        public virtual string YearDocument { get; set; }


        public override bool Equals(object obj)
        {
            //return AnoExercicio.ToString() == CodCliente.ToString() == CodGrupoFonte.ToString() == CodFonte.ToString();
            if (!(obj is EmpenhoDTO)) return false;

            var objA = obj as EmpenhoDTO;
            return (this.YearExerciseCTX == objA.YearExerciseCTX && this.CodClientCTX == objA.CodClientCTX && this.IdtDocument == objA.IdtDocument &&
                this.CodDocument ==objA.CodDocument && this.CodUg==objA.CodUg && this.YearDocument ==objA.YearDocument );


        }

        public override int GetHashCode()
        {
            return base.GetHashCode();
        }
    }
}