code: func (col *CorrelatedColumn) EvalInt(ctx sessionctx.Context, row chunk.Row) (int64, bool, error) {
  	if col.Data.IsNull() {
  		return 0, true, nil
  	}
  	if col.GetType().Hybrid() {
  		res, err := col.Data.ToInt64(ctx.GetSessionVars().StmtCtx)
  		return res, err != nil, err
  	}
  	return col.Data.GetInt64(), false, nil
  }
docs: // EvalInt returns int representation of CorrelatedColumn.