public 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();
  }