Chapter 4 Building Conceptual Data Models

Selecting a data type from a list of standard data types in a CDM

You can select a data type from a list of standard data types. This is the same list that is available in the Physical Data Model. PowerDesigner automatically maps the standard data type to a conceptual data type.

The length and precision are properties that do not apply to all data types. Furthermore, depending on data type, length may indicate a maximum or a fixed number of characters.

The tables below indicates the data types for which you can specify:

Numeric data types


Conceptual data type 		Physical data type (depending on the DBMS)

Content

Length
Integer int / INTEGER 32-bit integer —
Short Integer smallint / SMALLINT 16-bit integer —
Long Integer int / INTEGER 32-bit integer —
Byte tinyint / SMALLINT 256 values —
Number numeric / NUMBER Numbers with a fixed decimal point Fixed
Decimal decimal / NUMBER Numbers with a fixed decimal point Fixed
Float float / FLOAT 32-bit floating point numbers Fixed
Short Float real / FLOAT Less than 32-bit point decimal number
  • —
Long Float double precision / BINARY DOUBLE 64-bit floating point numbers —
Money money / NUMBER Numbers with a fixed decimal point Fixed
Serial numeric / NUMBER Automatically incremented numbers Fixed
Boolean bit / SMALLINT Two opposing values (true/false; yes/no; 1/0) —

Character data types




Conceptual data type 		Physical data type (depending on the DBMS)



Content



Length
Characters char / CHAR Character strings Fixed
Variable Characters varchar / VARCHAR2 Character strings Maximum
Long Characters varchar / CLOB Character strings Maximum
Long Var Characters text / CLOB Character strings Maximum
Text text / CLOB Character strings Maximum
Multibyte nchar / NCHAR Multibyte character strings Fixed
Variable Multibyte nvarchar / NVARCHAR2 Multibyte character strings Maximum

Time data types


Conceptual data type 		Physical data type (depending on the DBMS)

Content
Date date / DATE Day, month, year
Time time / DATE Hour, minute, and second
Date & Time datetime / DATE Date and time
Timestamp timestamp / TIMESTAMP System date and time

Other data types




Conceptual data type 		Physical data type (depending on the DBMS)



Content



Length
Binary binary / RAW Binary strings Maximum
Long Binary image / BLOB Binary strings Maximum
Bitmap image / BLOB Images in bitmap format (BMP) Maximum
Image image / BLOB Images Maximum
OLE image / BLOB OLE links Maximum
Other — User-defined data type —
Undefined undefined Not yet defined data type —

Steps To select a data type from a list of standard data types in a CDM:

  1. Select Model→Domains to display the list of domains.
  2. Click the domain to define and display an arrow at the beginning of the line.
  3. Click the Properties tool.

    or

    Double-click the arrow at the beginning of the line.

    The domain property sheet appears.
  4. Click the Question Mark button next to the Data Type dropdown listbox.

    Note   Selecting from the Data Type dropdown listbox
    You can also select a data type directly from the Data Type dropdown listbox.



    A list of standard data types appears.
  5. Click the radio button corresponding to the data type you want to apply.

    The code for the data type appears in the Code box.

    Note   Undefined data type
    If you do not want to select a data type immediately, you can choose the Undefined data type.



  6. Type the maximum number of characters for the data type in the Length box.
  7. If the data type includes values after a decimal point, type the number of places after the decimal point in the Precision box.
  8. Click OK.

    The change of data type appears in the Data Type box.

 

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