向FeatureClass中添加字段信息

public static void AddField(IFeatureClass fClass, string name, 
            string aliasName, esriFieldType esriFieldType,int lenght)
        {
            IFieldEdit pField = new FieldClass();
            IFieldEdit pFieldEdit = pField as IFieldEdit;

            pFieldEdit.Name_2 = name;
            pFieldEdit.AliasName_2 = aliasName;
            pFieldEdit.Length_2 = lenght;
            pFieldEdit.Type_2 = esriFieldType;
            fClass.AddField(pFieldEdit);
        }

 /// <summary>
        /// 得到Sde的FeatureWorkspace
        /// </summary>
        /// <returns></returns>
        private IFeatureWorkspace GetSdeWorkspace()
        {
            if (!ValidateSdeParam())
                return null;

            IPropertySet ps = GetConnectionParam();
            try
            {
                IWorkspaceFactory wf = new SdeWorkspaceFactoryClass();

                IWorkspace ws = wf.Open(ps, 0);

                return ws as IFeatureWorkspace;