Presentation on theme: "WFM 6202: Remote Sensing and GIS in Water Management"— Presentation transcript:
1 WFM 6202: Remote Sensing and GIS in Water Management [Part-B: Geographic Information System (GIS)]Lecture-4(b): Geo-DatabaseAkm Saiful IslamInstitute of Water and Flood Management (IWFM)Bangladesh University of Engineering and Technology (BUET)December, 2008
2 Lecture Topic Understand basic Geodatabase concepts and structure Know the advantages in using the Geodatabase formatManaging a GeoDatabaseCreating GeoDatabase
3 First Generation Storage/Linking AS400DatabaseAccessTabular DataSpatial DataTabular/Spatial data is linked outside the databaseLinks occur using unique IDs….Parcel NumbersStorage is still in separate locations
4 Second Generation Storage/Linking Geodatabases Tabular DataSpatial DataTabular/Spatial data is stored/linked in a single location!!
5 Benefits of a GeoDatabase Spatial & attribute data integrityIntelligent BehaviorCentralized Data StorageIncreased PerformanceAdvanced Analysis CapabilitiesMulti-user editing (SDE format)
6 Benefits of Migrating to a Geodatabase Data Integrity Maintain tabular data more efficientlyReduce typological data errorsMaintain spatial data more efficientlyReduce spatial errorsPro-West & Associates
7 What is a Geodatabase? A spatial and attribute data container Relational database management system (RDBMS)Maintains data integrityApply Rules and BehaviorNative data format for ArcGISRelational Database - A method of structuring data as collections of tables that are logically associated to each other by shared attributes. Any data element can be found in a relation by knowing the name of the table, the attribute (column) name, and the value of the primary key.
8 2 Types of Geodatabase Personal Geodatabase Enterprise Geodatabase Stand alone PC, MS Access databaseSupports individual and small groups on moderate size datasetsEnterprise GeodatabaseExists on underlying RDBMS through Spatial Database Engine (SDE) e.g. SQL ServerUsually runs on a dedicated serverSupports many users and massive datasetsSupports raster datasets
9 Two types of GeoDatabases PersonalAccessMulti-userSDEGISSQLSDEData StorageInterpreterView/AnalyzeThere are two types of GeoDatabases: Personal and Multi-user.A Personal Geodatabase uses Microsoft Access as the DBMS (Database Management System) which has certain limitations imposed by Access and limitations imposed by ArcGIS. It is a great learning tool, but may fall short of expectations due to some limitations listed later. All Personal GeoDatabases created with earlier (than 8.3) software should be upgraded to version 9.1. This is easily done within the Properties for the GeoDatabase.A Multi-user Geodatabase uses one of the supported DBMS’s listed below. It requires an SDE license and has the full suite of capabilities outlined in this chapter and more.As information is presented in this chapter, differences between the two will be pointed out.Supported DBMS’s (hardware platforms may differ):IBM DB2 Universal Database (UDB)INFORMIX Dynamic ServerMicrosoft SQL ServerOracle
10 The Personal Geodatabase It’s not Scary! Stores spatial and tabular data in an Access database formatSets the stage for future SDE geodatbase migrationEdit in ArcView, ArcEditor or ArcInfo
12 Geodatabase Elements Geodatabase Feature data set Geometric network Feature classRelationship classTableAnnotation class
13 GeoDatabase (GDB) structure StoresFeature datasetsFeature classesTablesRasterMoreA unique structure within the GDBOne might make the statement that we can store about any type of data for our GIS needs within a Geodatabase. For the most part that is true, as long as we differentiate between the “Personal Geodatabase” and the “Multi-User Geodatabase”. As mentioned earlier, the Personal Geodatabase makes use of MS Access to store the structured tables and their relationships needed to represent our GIS data. MS Access has limitations and prohibits the storage of certain data formats (for example, Rasters cannot be stored internally with the Personal Geodatabase due to size limitations).Because of these differences between personal and multi-user Geodatabases, one should consider the needs of the organization to determine the use of the system in setting up and choosing the RDBMS and how it will be part of the integrated system.The common structures you will work with in the beginning are: Feature Datasets, Feature Classes, Tables and Rasters. Certainly there are other objects that are available in a Geodatabase which you should learn as you advance. Each of the basic objects will be discussed on the following pages.
14 Feature Dataset Contains Feature Classes Required for Topology Must have same coordinate systemRequired for TopologyBehavior relationships between feature classes.
15 GDB Objects: Feature Dataset A collection of feature classesEnvironment for spatial referenceEnvironment for topologyEnvironment for coincident geometry and linked annotationFeature classes inherit spatial referenceData loaded areprojected on the fly,if necessaryThe feature dataset provides the user with the “framework” to organize logical collections of Feature classes (even different feature types – point, line, poly) together to represent the behavior and topologic relationships that the individual Feature classes share. The extent of the flexibility delivered in using Feature datasets is much more exhaustive and efficient than in previous models, such as coverages. Feature datasets are “user grouped” Feature classes (which are discussed on the next page). This allows the user to more accurately and efficiently model real world entities as “feature groupings” and establish topological relationships between those Feature classes that participate in the topology. All of this is accomplished as a structured collection of tables in the RDBMS, thus exploiting the performance benefits of the database.The Feature dataset name can be interpreted as the “container” for the groupings of the Feature classes listed “below and indented” under the Feature dataset.Benefit can be reaped from having a spatial reference defined for the Feature dataset so when new Feature classes are loaded into an existing Feature dataset, the data will “project on the fly” (if necessary) into the spatial reference of the Feature dataset.
16 Feature Class Stores a single feature type Point, Line, PolygonCan be standalone or member of a Feature datasetFeature DatasetFeature ClassStand Alone
17 GDB Objects: Feature Class (FC) A collection of featuresEach feature class has one geometry type (point, multi-point, line, polygon)Can be stored in afeature dataset or‘stand-alone’Attributes arestored withcoordinate datain one tableA Feature class is a collection of features. Features are vector data (which you learned in an earlier chapter as discrete x,y coordinates) and represent points, lines, or polygons.Feature classes can be “stand alone” or be grouped into Feature datasets to model more complex topologic relationships.
18 Spatial ReferenceIn setting up the Spatial Reference, ArcGIS provides a dialog allowing the user to select from a standard list of coordinate systems, import from other datasets already having a Spatial Reference defined, create a new coordinate system with all the particular parameters (which is tedious and difficult), or modify an existing coordinate system. The Spatial Reference also defines the maximum spatial extent for the data.Other parameters of the Spatial Reference for the Geodatabase are:X/Y Domain – The “bounding rectangle” or extent of the feature class or feature dataset. It is specified with the minimum X value, minimum Y value, maximum X value, and maximum Y value.Z Domain – The maximum range of “Z” values for the data. For example: 0 to (Sea Level to a peak of ft maximum elevation)M Domain – The maximum range of Measure units (this can be time or distance ranges). This tolerance is also the only exception to the rule regarding consistency; feature classes within the same feature dataset can have different Measure domains.A
19 Coordinate domain Extent of available coordinates Min and max X,Y coordinatesPrecision = storage units per map unitExample, 1000 mm per meterMake sure it covers study areaAllow for growthArcCatalog defaultImport: data plus room for growthSet your ownImport from existing dataType in extent for study areaCoordinate domain:Spatial domain is best described as the allowable coordinate range for x,y coordinates. Precision describes the number of divisions per one unit of measure. A spatial reference with a precision of 1 will store integer values, while a precision of 1,000 will store one thousandth of a unit.The spatial domain for a feature class or feature dataset cannot be changed. If the required x-, y-, m-, or z-value ranges for your database increases, the data has to be reloaded into feature classes with a spatial reference that accommodates the new domain.You must store your coordinates at a specific precision. For best results, ensure that the chosen precision will support the accuracy of your data. The ArcCatalog loading wizard will look at your data and determine defaults for your precision and database growth. Naturally, it is impossible for ArcCatalog to understand your intentions, so the default settings often are not the best choice. It is important that you understand domains.The geodatabase stores coordinates as a 4-byte integer that has a maximum value of 2,147,483,648. You decide what the units represent. For instance, if you need to store meter accuracy, then you have 2.1 billion meters to work with. If you decide to store centimeters, you would have 2.1 billion centimeters to work with. These are called storage units. You should set your storage units based on your accuracy..Map units are the measurement units of your data, and have nothing to do with accuracy. They are the units that represent measurements. For example, the meter is the standard unit for UTM data, while the foot is the standard unit for a state plane coordinate system.2.14 billion storage units
20 DomainA property of a feature dataset or feature class (cannot change once set)The domain of the feature coordinates is, essentially, the minimum and maximum ranges available for feature values, for feature classes, and for feature datasets. The exception is the Measure Domain for feature classes in a feature dataset. Feature classes in a feature dataset may have different Measure Domains.The Feature Coordinate domains are set up upon creation of the data in ArcCatalog. All data that will be loaded in the future will have to adhere to the valid domains.The precision of a domain will affect the extent of that domain. The spatial domain for a feature class or feature dataset cannot be changed once it is established. Here is a very short list of example precisions and the corresponding x/y domain:Note: Precision does not have to be base 10 numbers, although this is easiest to understand.PrecisionMin. ValueMax. Value12,147,483,64510002,147,483,645,00010214,748,364.510021,474,836.45
21 Domains Spatial Attribute Range of values (e.g., 0-100) Coded values (e.g., 1 = potatoes 2 = wheat)Briefly describe the different types. Most have been used in basic GDB already.Coded values is new useRecall, data type must match between the domain and the attribute where the domain is going to be implementedWhy use a domain????? [BRAINSTORM]
22 The Spatial DomainThe Geodatabase stores all geometry coordinates as positive integersFaster Display, Processing, and AnalysisBetter Compression (DBMS only)Efficient for managing topologic relationshipsLimited to 2,147,423,647 storage units.2.14x109 meters, or miles, or inches, or ...
23 Accuracy and Precision Accuracy in the DataScale of source map scale will determine accuracy*1:600 (1”=50’) ± 1.7 feet1:1,200 (1”=100’) ± 3.33 feet1:2,400 (1”=200’) ± 6.67 feet1:4,800 (1”=400’) ± feet1:24, ± feetPrecisionAbility to store the accuracySignificant digitsSingle precision 6-7 precise digitsDouble precision precise digitsGeodatabase 0-10 precise digitsAccuracyThe quality of the source document used for data automation (the map) must be taken into account for the desired level of accuracy for the user applications. Accuracy can be thought of as the “correctness” of the data – is it at the correct x/y location?PrecisionPrecision can be thought of as the ability to store the accuracy of the data. If the data is highly accurate +/- 1.7 feet, the Geodatabase units must store at least 1 foot as the unit of measure. The Precision, as the GDB makes use of it, is a “multiplier” to provide digits of precision after the decimal place for the coordinates. All GDB values are in Integer, but with the multiplication being applied “behind the scenes” and transparent to the user.Coordinate offsetIf you find that your coordinate domain range is adequate to support the precision desired, but either the x or y values are exceeding the 2,147,483,648 maximum, a shift can be applied to account for the limitation. This shift is determined by finding the center of your coordinate system and accounting for the offset. Calculating the shift and scale establishes the precision and storage of the data in the GDB, and once the data is loaded, you will never directly interact with the numbers again – all work will be done in floating point numbers (as in the source data).The shift calculation gets beyond the intended scope of this class. For the purposes of the exercises, defaults are taken for the precision once the coordinate domain is set for a specific state.
24 Example: Spatial Domain All GIS Features Must Fit Within this Positive, 32-bit Integer Space.OFF LIMITS2,147,423, ,147,423,6470 0The Database’s Spatial Domain
25 Standard Fields Feature classes have default fields ObjectID – unique identifierShape – contains coordinates of featureArea – automatically calculated and maintained for polygonsShape_Area (Personal GDB)Length – automatically calculated and maintained for lines and polygonsShape_Length (Personal GDB)Part of the structure for every feature class attribute table are the “standard fields”. Users should view these fields as “maintained by the software”.Many operations we perform with ArcGIS modify the geometry of the spatial data. Whether we are “slicing and dicing” land polygons or road lines, or merging and reshaping features in an edit session; geometric coordinates are often modified as we continually manage our geographic data.Polygons, for instance have area and length properties. As we would hope, when we edit a polygon feature, the software will update the affected polygon area and perimeter.The Shape field, though visually on our screen lists the type of geometry by name (polygon, polyline, point) actually stores the X and Y coordinates needed to represent the feature being tracked by the specific record in the database. This “blob” (binary large object) of coordinates can handle non-contiguous features such as multi-part polygons, and linear routes with gaps.Beyond the “standard fields”, additional fields added to the feature class are said to be “user defined”.
26 Spatial Reference Property of a feature class or feature dataset ComponentsCoordinate systemCoordinate domainPermanent after definition is savedWarning: it may look like you changed the coordinate system, but you can’t and don’t try. It messes things up!See next slide for more informationMap features represent real world objects (entities like streams, roads, etc.). The positions of the objects on the earth’s 3-D surface are measured in geographic coordinates (latitudes and longitudes). Latitudes and Longitudes are not uniform units of measure. In remedying this measurement problem, data is transformed from 3-D coordinates into 2-D projected coordinates. By converting from geographic referenced coordinates to projected coordinates, we can easily represent one or two spatial properties (of four) accurately:Shape, Area, Distance, or DirectionNo coordinate system represents an accurate system for all four properties at the same time.Users should choose a coordinate system that maintains the properties that are most important to their business. Once determined, the Coordinate System can be stored in the Spatial Reference for feature classes, feature datasets, and the overall Geodatabase. A performance “boost” is realized when all data is in the same Spatial Reference, plus it makes it nice when loading data into the Geodatabase having a coordinate system defined – ArcGIS will “project on the fly” to load the data into the Geodatabase coordinate system.
27 Storing Feature Coordinates Two important considerations when storingfeature coordinates in a Geodatabase:All data is stored as positive, 32-bit integers (Spatial Domain)All data must maintain a Coordinate Precision.
28 Coordinate PrecisionThe geodatabase converts all coordinates into 32-bit Storage Units.Storage Units are the smallest measurable unit that can be stored in a Geodatabase.Precision is used to convert coordinate system units into storage units.
29 Example: Coordinate Precision Precision is a Scale FactorUsed to preserve decimal places before roundingLarger precision preserves more digitsFloating Point Coordinate in ArcGIS( )Multiply by Precision × 1000Divide by Precision ÷ 1000Integer Storage Unit in a Geodatabase (123456)X = Precision =1000
30 Example: Precision Preservation Coordinate System Units PrecisionStorage Units =Coordinate system units÷Precision=Storage unitsMeters1001 cm10001 mm502 cmFeet121 inch
31 Topology Objects Maintain data integrity Feature Dataset required Within feature classBetween feature classFeature Dataset requiredFunctionalityDisplay Topology ErrorsSelect and Correct ErrorsValidationRegarding map features, topology is relationship between features connectivity and adjacency.Geodatabase topology provides tools to ensure integrity of spatial data.
32 Selected Topology Rules 25 available topology rules2 Rules currently appliedMust Not OverlapMust Not Have Gaps
33 File Management Compacting the Personal Geodatabase Procedure Reduces file sizeProcedureIn ArcCatalog, right click on the .mdb fileSelect the Compact Database option in the context menu
34 Reference Data Locations Proscribed by the Standard for Geospatial Dataset File NamingStandard folder structure on shared f: driveGeodata – top level geospatial data folderLocal Geodata Administrators have authority to create, delete, and change folders, but only as outlined in the standards document.
35 Data Management File Naming Standards The current standard has 23 common geospatial dataset categories such as soils that consist of 1 or more geospatial datasets.<disk drive>:geodataplants<geospatial dataset category (directory / folder)>soils<geospatial dataset category (directory / folder)>There have been several standards developed regarding many facets of the GIS Implementation. One of these is the Standard for Geospatial Dataset File Names.The objectives of this Standard are to help in managing geospatial data by establishing directory (folder) and file naming conventions to support a nationally consistent set of core geospatial data. This will provide a foundation on which to build customized business applications such as the Customer Service and Wetland Toolkit and the Soil Data Viewer. Nationally fielded applications will be developed that rely on a consistent set of geospatial data. These applications will rely on the integrity of the data in meeting the specifications in this Standard. It is recommended that applications built locally for a Service Center or for data that is acquired locally should also adhere to these standards.Another reason to comply with this file and directory naming convention is to organize this data at the Service Center so that it is accessible, maintainable and updateable.It also provides guidance on the directory structure and file naming for locally acquired and derived geospatial data.The latest version of this standard is provided as a MSWord document on this CD-ROM.soil_a_ks057<geospatial dataset>soil_p_ks057<geospatial dataset>soil_l_ks057<geospatial dataset>topographic_images<geospatial dataset category (directory / folder)>
36 Data Management File Naming Standards cont. Elements of a file nameLocation: Alpha or numeric FIPS codesoil_a_ks057Feature categoryFeature type: a-polygon, l-line, p-point, t-table, i-image, etc.There have been several standards developed regarding many facets of the GIS Implementation. One of these is the Standard for Geospatial Dataset File Names.The objectives of this Standard are to help in managing geospatial data by establishing directory (folder) and file naming conventions to support a nationally consistent set of core geospatial data. This will provide a foundation on which to build customized business applications such as the Customer Service and Wetland Toolkit and the Soil Data Viewer. Nationally fielded applications will be developed that rely on a consistent set of geospatial data. These applications will rely on the integrity of the data in meeting the specifications in this Standard. It is recommended that applications built locally for a Service Center or for data that is acquired locally should also adhere to these standards.Another reason to comply with this file and directory naming convention is to organize this data at the Service Center so that it is accessible, maintainable and updateable.It also provides guidance on the directory structure and file naming for locally acquired and derived geospatial data.The latest version of this standard is provided as a MSWord document on this CD-ROM.A geospatial dataset file name should:be less than 30 characters longconsist of lower case a-z and numerals 0-9first character always a-z
37 Data Storage and Backup Shared data in a service center must be on the f: drive.Personal data can be stored on the c: drive or h: drive.c: drive is not routinely backed up.h: drive should contain important working files that can be routinely backed up.Local Geodata Administrators are responsible for ensuring backups are routinely being made of specific directories.Large, easily replaced datasets should not be routinely backed up because they can be obtained again.Files and directories that change regularly should be routinely backed up.
38 GDB Design A critical step UML modeling for ArcGIS Class diagrams IBM Rational RoseMS VisioClass diagramsUnified modeling language
39 Managing Your GDB ArcCatalog is your main tool to manage the schema Construction of component partsOrganization of those partsProperties for the partsMany capabilities are availableSome are not on the default GUIArcCatalog is your main tool for managing your Geodatabase. Almost all capabilities you will need (unless it is CASE tools) are available in ArcCatalog either through choosing the correct context sensitive menu or through choosing the correct tool.Bear in mind there are advanced capabilities present in ArcCatalog, but they are not installed on the default user interface. To access these capabilities, you will need to customize your tool set. See the topic Customizing ArcMap and ArcCatalog in the Help tool.
40 Reading SchemasMost data access technologies provide a way for you to query the schema of a database, and obtain information about the tables, stored procedures, data types, users, and other content of a database.LogicalStructural
41 Creating a GDB Personal Multi-user Use ArcCatalog Must be done at the system levelTo create a Personal Geodatabase, you simply have to right-click while pointing your cursor at a directory. This will bring up a context-sensitive menu where you would choose New > Personal Geodatabase. You will then have the opportunity to rename the new Personal Geodatabase.Creating a multi-user Geodatabase is beyond the scope of this class and must be performed by your system administrator.A
42 Creating a new personal geodatabase Open ArcCatalogChoose a folder locationRight click: Choose New < Personal Geodatabase
43 Right click your geodatabase Choose: New < Feature Dataset Creating Feature DatasetsRight click your geodatabaseChoose: New < Feature Dataset
44 Creating an empty feature class Two locations available: stand-alone and within a feature datasetAgain, right-click on your feature dataset where you wish to place a feature class. Perform these activities:Choose New > Feature classClick on ShapeSet Geometry TypeSet your Spatial ReferenceAdd and define additional attributes.The resulting feature class will have all the properties for storing your geographic data, but will contain no data.Note: be certain to define the shape geometry type: Line, Multipoint, Point, or Polygon.You can add other attributes to the feature class by clicking on a blank field in the Field Name list, defining a name and the fields properties.A
45 Creating a feature dataset By right-clicking on your Geodatabase (either Personal or Multi-User), you can choose New > Feature Dataset.Simply fill out the information panels with the appropriate information. Be sure to specify your coordinate domains correctly, since this will control all feature class data placed within the Feature Dataset.A
46 Right click your geodatabase Choose: New < Feature Dataset Creating Feature DatasetsRight click your geodatabaseChoose: New < Feature Dataset
47 Feature Datasets: Setting the spatial reference Set the ProjectionSet the DomainPrecisionExtent:Search on Spatial Domain
48 Import existing dataNavigate to the feature dataset or geodatabase icon in ArcCatalogRight ClickChoose ImportUse this to import any existing format!
49 Subtypes & Domains Subtype: Domain: Distinguish features within a single layerMaintain different domains within the same fieldNeed ArcEditor or ArcInfoDomain:Identify & constrain attribute valuesCan utilize in ArcView
50 Subtypes & Domains Parcels ExampleSubtype: Boundary LineDomains:ROW Type
51 Subtypes Must be long or short integer fields Created in ArcEditor or ArcInfoIncreases the efficiency of the editing processUse whenStandardizing a legenddistinguishing different default values/domains within the same field
52 Creating Subtypes In ArcCatalog Double click on a feature class Select the Subtype tab
53 Creating Domains Created in ArcCatalog Double Click on the Personal Geodatabase IconChoose the Domains tab
54 Creating Domains—Assigning to Feature Classes In ArcCatalogDouble click a feature classChoose the Fields tabHighlight a fieldClick Domain under the Field properties section
55 Creating Domains—Assigning default values Set in the Field Properties sectionUse default values for common entries
57 Geodatabase Topology Putting the power into your hands Topology RulesPreset rules to define topological relationships to ensure connectivity, adjacency and coincidenceCan be changed at any timeTopology ToolsMaintain spatial relationshipsToolbar and TasksPro-West & Associates
58 Creating Topology Rules Cluster Tolerance Ranks Land use boundaries overlap parcel boundariesManholes overlap sanitary line endpointsCluster ToleranceMin distance where vertices within tolerance are snappedRanksControl what features move during validatingSurveyed points will not move (snap) during the validation processPro-West & Associates
59 Validating Topology Validate edited features using set topology rules Evaluate rules/tolerance and generates error notificationsSnaps vertices using set cluster tolerance and ranksPro-West & Associates
60 Create a New Topology Created in ArcCatalog Created within a Feature DatasetTopology WizardAllows user to set Rules, Ranks, Tolerance, and perform initial ValidationPro-West & Associates
61 When added to ArcMap, will show errors from the validation process Final TopologyWhen added to ArcMap, will show errors from the validation process
62 Managing TopologiesRight click on the Topology in ArcCatalog
63 Topology Tools Maintenance Standard toolbar in ArcView-ArcInfoUsed in an editing environment in ArcMapUse in conjunction with Topology Tasks in Editor ToolbarPro-West & Associates
64 Editor Toolbar Maintenance Topology Tasks:Modify, Auto Complete Polygon and ReshapeAllows user to use basic editing tools to alter vertices, replace lines, add adjacent polygons or alter existing polygonsUse in conjunction with the Topology Edit Tool on the Topology ToolbarRemember:Set snapping and snapping tolerance
65 Flexible Editing Topology edit tool Show shared features tool Allows for editing shared boundariesBuilds a temporary topology cache within a given extentFaster performanceMust use each time your extent changesShow shared features toolMove a boundary without effecting shared boundaries (temporary)Parcels & land useParcels and easementsPro-West & Associates
66 Validate & Fix Validate after editing is complete Errors are highlightedClick the Fix Error buttonSelect a feature and right clickFixMark as an ExceptionDo Nothing
67 Process in Review Plan for success Import data Set Subtypes & Domains Create TopologyStart editing!Pro-West & Associates
68 Tips Projecting data PGDB is 2 GB max Must create a new feature classPGDB is 2 GB maxRead-only on a PGDB will restrict some analyses, such as Select by LocationUse compact to clean up temporary filesAll table names need to be uniqueThere are a number of tips you may find helpful as you work with a Geodatabase:If you wish to project your feature class data into another coordinate system, you must create a new feature class. You should not attempt to change the coordinate system properties. Right-click on your feature class and choose Export > Geodatabase to Geodatabase.If you have more than one Geodatabase (either type), you can drag and drop feature classes or feature datasets from one to another.A Personal Geodatabase has a 2 Gigabyte maximum. Also, no rasters, CAD data or custom objects can be stored in Personal GeoDatabases.If you place a read-only property on a Personal Geodatabase (since it is really a single file on your disk), you will be restricted on some activities such as Select by Location. This action requires temporary tables to be written to the Geodatabase.Lots of temporary tables get written to a Geodatabase when certain activities are performed (such as Select by Location). To clean these tables out, use Compact.All table names must be unique in a Geodatabase. This includes all feature classes inside or outside of a feature dataset.
69 Ex 2 Create a Personal GDB Create an empty Feature Class Create a Feature DatasetCreate a Feature Class within the Feature Dataset