QR-Code Drawer In None
Using Barcode drawer for Software Control to generate, create QR Code image in Software applications.
Read Denso QR Bar Code In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
8-1-3 Data Element Descriptions In Sec 8-1-2 we listed traditional and essential characteristics of the attributes describing the data elements Schema entries which complement these essential but programming oriented characteristics will be listed in this section These schema entries provide information beyond the programs needs Recording the characteristics shown here can greatly improve the automatic and manual aspects of the database interface presented to the users
Print QR Code 2d Barcode In C#
Using Barcode drawer for .NET Control to generate, create QR-Code image in VS .NET applications.
Denso QR Bar Code Creation In Visual Studio .NET
Using Barcode creator for ASP.NET Control to generate, create QR Code ISO/IEC18004 image in ASP.NET applications.
Title A descriptive sentence or title may be desired which allows a more detailed identi cation of the data elements than the program language name permits Sometimes the title can also include abbreviations, synonyms, antonyms, or aliases Specialist in a subject area often use abbreviations unique to their eld of discourse when specifying a data element for entry or retrieval When data are shared among a larger audience, a full identi cation or title is required For example, the variable bp dst will have the title: "Diastolic bloodpressure, measured with patient sitting"
QR-Code Printer In VS .NET
Using Barcode maker for VS .NET Control to generate, create QR Code 2d barcode image in .NET framework applications.
Generate QR Code In VB.NET
Using Barcode drawer for .NET framework Control to generate, create QR-Code image in VS .NET applications.
EAN / UCC - 14 Drawer In None
Using Barcode generation for Software Control to generate, create GS1 128 image in Software applications.
Create UPC Symbol In None
Using Barcode printer for Software Control to generate, create UPC-A Supplement 5 image in Software applications.
Unit Speci cation
Code-39 Creation In None
Using Barcode printer for Software Control to generate, create USS Code 39 image in Software applications.
Print Code 128B In None
Using Barcode creator for Software Control to generate, create Code 128A image in Software applications.
De ning the Elements for a Database
EAN13 Printer In None
Using Barcode printer for Software Control to generate, create GTIN - 13 image in Software applications.
Draw DataMatrix In None
Using Barcode creation for Software Control to generate, create Data Matrix image in Software applications.
A code or identi cation of the units of measurement for numeric data elements is often important It might be essential to know whether a pressure is stated in pounds force per square inch, atmospheric fractions, millibars, millimeters or inches of mercury, kilograms per square centimeter, pascals, or football players per quarterback The unit speci cation might be used only for reporting or veri cation of domain matching when les are joined, but could also be used to convert values automatically if the system has the necessary conversion factors available
Create Bookland EAN In None
Using Barcode maker for Software Control to generate, create International Standard Book Number image in Software applications.
Scanning UCC - 12 In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
Essential Data An indication of whether this data element is essential or optional in the record may have to be maintained We may wish to prevent the creation of records which have critical elements missing An employee le needs to have a social security number and a departmental assignment for every employee Other elds, such as a spouse name or a health certi cation, may be optional
Recognizing Data Matrix 2d Barcode In C#.NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in .NET framework applications.
Recognize UPC-A In VS .NET
Using Barcode decoder for .NET framework Control to read, scan read, scan image in VS .NET applications.
If data can be missing or left unde ned, it becomes necessary that programs which operate on the database recognize this fact Unde ned values are due to several causes
Code 39 Generator In Java
Using Barcode maker for Android Control to generate, create Code 39 image in Android applications.
Creating Data Matrix ECC200 In VB.NET
Using Barcode creator for .NET Control to generate, create ECC200 image in VS .NET applications.
Unde ned Values
Painting Code-128 In None
Using Barcode drawer for Office Excel Control to generate, create Code 128 Code Set A image in Excel applications.
Universal Product Code Version A Creation In VB.NET
Using Barcode maker for .NET Control to generate, create Universal Product Code version A image in VS .NET applications.
Missing data Some data values may not have been available or known when the remainder of the record was entered Not applicable Some attributes may not be relevant in some records, especially when subrelations are combined into a le Not collected Some past data may be unavailable in areas where the scope of the database has expanded over time In the design of a new system or the change of an existing one there is an opportunity to add new capabilities This means that new data elements have to be described and their structural relationships charted The new database will then have attributes for which no past values are available To manage these cases of unde ned a notation in the database is needed The schema must assign a value representation which does not con ict with legal values in the domain of the attribute It is not clear if distinct values are needed for the three cases above, although the di erence between not applicable and missing can lead to di erent actions Very few programming systems make appropriate provisions to handle any kind
of unde ned values in a manner distinct from zero values The programmers are then forced to use codes as -1, -0, 999999, 'undefined', and the like These codes invariably nd their way into computations and lead to major errors Some statistical systems have provisions for missing data, and the database can provide the required input format automatically For programming systems which do not handle unde ned values the databases system should trigger an exception procedure when an unde ned value is accessed, so that the processing programs will not compute nonsense Nonsense can be created for instance if a join operation creates result tuples for null = null This type of problem can be avoided by never equating a null value with another null value, ie, by treating each null value as distinct In counting operations null values should be ignored, so that they do not distort computed averages or deviations Not all problems are solved by these rules, and more sophisticated schemes have been proposed but have never been used in practice