public sealed class FieldDescription : Description 

FieldDescription bigIntegerFieldDescription = new FieldDescription("BigInteger_64", FieldType.BigInteger);

// 64-bit
FieldDescription oidFieldDescription_64 = new FieldDescription("ObjectID_64", FieldType.OID)
{
  Length = 8
};

// 32-bit
FieldDescription oidFieldDescription_32 = new FieldDescription("ObjectID_32", FieldType.OID)
{
  Length = 4
};

// Earthquake occurrences date and time

// 9/28/2014 (DateOnly)
FieldDescription earthquakeDateOnlyFieldDescription = new FieldDescription("Earthquake_DateOnly", FieldType.DateOnly);

// 1:16:42 AM (TimeOnly)
FieldDescription earthquakeTimeOnlyFieldDescription = new FieldDescription("Earthquake_TimeOnly", FieldType.TimeOnly);

// 9/28/2014 1:16:42.000 AM -09:00 (Timestamp with Offset)
FieldDescription earthquakeTimestampOffsetFieldDescription = new FieldDescription("Earthquake_TimestampOffset_Local", FieldType.TimestampOffset);

// 9/28/2014 1:16:42 AM (DateTime)
FieldDescription earthquakeDateFieldDescription = new FieldDescription("Earthquake_Date", FieldType.Date);

public void CreateFeatureDatasetWithFeatureClassSnippet(Geodatabase geodatabase)
{
  // Creating a FeatureDataset named as 'Parcel_Information' and a FeatureClass with name 'Parcels' in one operation

  string featureDatasetName = "Parcel_Information";
  string featureClassName = "Parcels";

  SchemaBuilder schemaBuilder = new SchemaBuilder(geodatabase);

  // Create a FeatureDataset token
  FeatureDatasetDescription featureDatasetDescription = new FeatureDatasetDescription(featureDatasetName, SpatialReferences.WGS84);
  FeatureDatasetToken featureDatasetToken = schemaBuilder.Create(featureDatasetDescription);

  // Create a FeatureClass description
  FeatureClassDescription featureClassDescription = new FeatureClassDescription(featureClassName,
    new List<FieldDescription>()
    {
      new FieldDescription("Id", FieldType.Integer),
      new FieldDescription("Address", FieldType.String)
    },
    new ShapeDescription(GeometryType.Point, SpatialReferences.WGS84));

  // Create a FeatureClass inside a FeatureDataset
  FeatureClassToken featureClassToken = schemaBuilder.Create(new FeatureDatasetDescription(featureDatasetToken), featureClassDescription);

  // Build status
  bool buildStatus = schemaBuilder.Build();

  // Build errors
  if (!buildStatus)
  {
    IReadOnlyList<string> errors = schemaBuilder.ErrorMessages;
  }
}

public void CreateFeatureClassInsideFeatureDatasetSnippet(Geodatabase geodatabase)
{
  // Creating a FeatureClass named as 'Tax_Jurisdiction' in existing FeatureDataset with name 'Parcels_Information'
  string featureDatasetName = "Parcels_Information";
  string featureClassName = "Tax_Jurisdiction";

  // Create a FeatureClass description
  FeatureClassDescription featureClassDescription = new FeatureClassDescription(featureClassName,
    new List<FieldDescription>()
    {
      new FieldDescription("Tax_Id", FieldType.Integer),
      new FieldDescription("Address", FieldType.String)
    },
    new ShapeDescription(GeometryType.Point, SpatialReferences.WGS84));

  FeatureDatasetDefinition featureDatasetDefinition = geodatabase.GetDefinition<FeatureDatasetDefinition>(featureDatasetName);

  SchemaBuilder schemaBuilder = new SchemaBuilder(geodatabase);

  // Create a FeatureClass inside a FeatureDataset using a FeatureDatasetDefinition
  schemaBuilder.Create(new FeatureDatasetDescription(featureDatasetDefinition), featureClassDescription);

  // Build status
  bool buildStatus = schemaBuilder.Build();

  // Build errors
  if (!buildStatus)
  {
    IReadOnlyList<string> errors = schemaBuilder.ErrorMessages;
  }
}

public void RemoveFieldTableSnippet(Geodatabase geodatabase)
{
  // Removing all fields from 'Parcels' table except following 
  // Tax_Code
  // Parcel_Address

  // The table to remove fields
  string tableName = "Parcels";

  TableDefinition tableDefinition = geodatabase.GetDefinition<TableDefinition>(tableName);
  IReadOnlyList<Field> fields = tableDefinition.GetFields();

  // Existing fields from 'Parcels' table
  Field taxCodeField = fields.First(f => f.Name.Equals("Tax_Code"));
  Field parcelAddressField = fields.First(f => f.Name.Equals("Parcel_Address"));

  FieldDescription taxFieldDescription = new FieldDescription(taxCodeField);
  FieldDescription parcelAddressFieldDescription = new FieldDescription(parcelAddressField);

  // Fields to retain in modified table
  List<FieldDescription> fieldsToBeRetained = new List<FieldDescription>()
  {
    taxFieldDescription, parcelAddressFieldDescription
  };

  // New description of the 'Parcels' table with the 'Tax_Code' and 'Parcel_Address' fields
  TableDescription modifiedTableDescription = new TableDescription(tableName, fieldsToBeRetained);

  SchemaBuilder schemaBuilder = new SchemaBuilder(geodatabase);

  // Remove all fields except the 'Tax_Code' and 'Parcel_Address' fields
  schemaBuilder.Modify(modifiedTableDescription);
  schemaBuilder.Build();
}