DataSet DataTable AsEnumerable linq

//必须要引用的两个命空间

using System.Data;
using System.Linq;

public void UpdateFormulaSet(FormulaSetFilterCondition entity)
        {
            var dataAccess = new FormulaAccess();
            var dtsResult = dataAccess.getFormulaSet(new FormulaSetFilterCondition() {CoID = entity.CoID, iFormulaID = entity.iFormulaID });
            if (dtsResult.Tables.Count > 0 && dtsResult.Tables[0].Rows.Count > 0 )
            {
                var rowCollection = dtsResult.Tables[0].AsEnumerable().Count(exp=>exp["iID"].ToString() != entity.iID.ToString());
                if(rowCollection > 0)
                {
                    throw new Exception("该公司下已经存在公式");
                }
            }
            dataAccess.UpdateFormulaSet(entity);
        }

-

public static string[] getLicInfo(string key, string strFilePath)
        {
            var dtsResult = LicenceFileReader.LicReader.ReadLicPath(strFilePath);
            var licInfo = dtsResult.tCommonLimit.OfType<tCommonLimitRow>().Where(exp => exp.ID.Equals(key)).FirstOrDefault();
            if(licInfo != null)
            {
                return new string[] { licInfo.ID, licInfo.Desc, licInfo.AuthFlag };
            }
            return null;          
        }