HP 3000 Manuals HP 3000 Manuals
STRUCTURE OF THE DATA BASE
It is not necessary to understand all the IMAGE features in order to use
QUERY. However, it is important to have a general idea of data base
structure and know the definitions of some IMAGE terms which will be used
in this manual.
Each item of information in a data base is referenced by a data item
name. The name associates the information with characteristics which
describe it:
* the type of information (numeric, alphanumeric, etc)
* its relation to other data in the data base
* the passwords required to read and/or write the information
The data base designer organizes data items into data sets for the
purpose of accessing them as a group. For example, an employee data set
could contain the items EMPID, F-NAME, L-NAME, SOCSEC#, and SALARY. A
credit union data set could contain EMPID, AMOUNT, TRANSCODE, and so
forth. Each data set is referenced by a data set name.
Each time you enter a new employee's record into the data base, you can
supply a value for each data item. This group of values is stored as a
single data entry in the data set. For example:
F-NAME SALLY
L-NAME MERTON
SOCSEC# 527-58-6492
SALARY 18000.02
QUERY allows you to locate particular entries which have values you
specify. You can then change the values or print them in a report. You
can also add or delete an entire entry if your password gives you the
capability to write to every data item in the data set.
You can use the FORM command to display the names of each data set to
which you have access and the names of the data items in those sets.
Only the items to which you have at least read access are listed.
Fully-Qualified Data Item Names
If you are referring to a data item which appears in more than one data
set and/or data base, you must specify which data set and data base to
access. A particular data item can appear in more than one data set
within a given data base, and a particular data item can appear in more
than one data base. You can specify the data item in three ways:
* by specifying the data set through the DATA-SET= command and the data
base through the DBLIST= command.
* by specifying the data set through the DEFINE command (DATA-SETS=
prompt) or through the MULTIDB command (DATA-SETS= prompt).
* by qualifying the data item name.
A fully-qualified data item name has the following form:
data base name:data set name.data item name
For example:
IRONCO:LABOR.BADGE#
^ ^ ^
| | |
data base name data set name data item name
BADGE# is the name of a data item in the data set named LABOR which is in
a data base named IRONCO. If BADGE# is also the name of a data item in a
data set named EMPLOYEE, which is in the IRONCO data base, its
fully-qualified name would be IRONCO:EMPLOYEE.BADGE#.
Data Types
The data base designer defines each data item as a particular type
depending on what kind of information is to be stored in the item. A
data item may be one of several types of integers, real or floating-point
numbers, or ASCII character information.
The FORM command can display the data type for each item. When using
QUERY, you will usually be unconcerned with the specific data type with
the following exceptions:
* when supplying values for an item, either to enter new information or
to locate specific entries, you may want to know the acceptable range
of values for a numeric type item.
* when creating reports you should be aware of the item types in order
to format the report properly.
* when using the QUERY registers while printing a report, it is helpful
to know how calculations affect the register values.
Detailed information about each of these situations is given with the
appropriate command in Section 3. Table 1-1 contains a summary of the
data item types and the range of acceptable values for each.
Data Values
If you use QUERY to enter a value for a data item of type P (packed
decimal), you should be aware of the way QUERY handles the sign of the
value. A different code is used for the sign of a value entered with a
plus sign than for a value entered without a sign. However, when QUERY
retrieves unsigned and positive type P data items with the same value,
they are considered to be equivalent. For example, +2 and 2 are
equivalent. Data items with values +0, 0, and -0 are also equivalent.
Literals
When specifying the value of a particular data item, you must sometimes
surround the value with quotation marks. This type of value is called a
literal. A character or string literal contains alphanumeric characters.
For example:
"TANYA OAKLEY" "ZXR-93458273" "3215"
Character literals containing numeric values of the types listed under
Integer or Real in Table 1-1 are called, more specifically, numeric
literals. For example:
"5468" "+408E-15" "-16.73892"
Rules for using quotation marks are described with the commands which
allow or require their use.
Table 1-1. Data Item Types and Values
-----------------------------------------------------------------------------------------------
| | | |
| TYPE | MINIMUM | MAXIMUM |
| | | |
-----------------------------------------------------------------------------------------------
| | | |
| INTEGER | | |
| | | |
| I1 | -32768 | +32767 |
| | | |
| I2 | -2,147,483,648 | +2,147,483,647 |
| | | |
| I4 | -9,223,372,036,854,775,808 | +9,223,372,036,854,775,807 |
| | | |
| J1 | -9999 | +9999 |
| | | |
| J2 | -999999999 | +999999999 |
| | | |
| J4 | -999999999999999999 | +999999999999999999 |
| | | |
| K1 | 0 | +65535 |
| | | |
| K2 | 0 | +4,294,967,295 |
| | | |
| Zn * | - (n digit number) | + (n digit number) |
| | | |
| Pn * | - (n - 1 digit number) | + (n - 1 digit number) |
| | | |
-----------------------------------------------------------------------------------------------
| | | |
| REAL | | |
| | | |
| R2 | -1.157920 x 1077 | -0.863617 x 10-77 |
| | | |
| | +0.863617 x 10-77 | +1.157920 x 1077 |
| | | |
| | | Largest accurate absolute integer |
| | | is 8,388,607. (QUERY rounds to 6 |
| | | digits when printing R2 values.) |
| | | |
| R4 | -1.157920892373161 x 1077 | -0.8636168555094445 x 10-77 |
| | | |
| | +0.8636168555094445 x 10-77 | +1.157920892373161 x 1077 |
| | | |
| | | Largest accurate absolute integer |
| | | is 36,028,797,018,963,967. (QUERY |
| | | rounds to 16 digits when printing |
| | | R4 values.) |
| | | |
-----------------------------------------------------------------------------------------------
| | | |
| CHARACTER | | |
| | | |
| Un ** | 1 ASCII uppercase character | n ASCII uppercase characters |
| | | |
| Xn ** | 1 ASCII character | n ASCII characters |
| | | |
-----------------------------------------------------------------------------------------------
Notes on Table 1-1.
* n cannot exceed 255 and must be even for type Z and evenly divisible
by 4 for type Pn. QUERY reports print at most 20 digits for type Z and
19 digits for type P data values.
** n cannot exceed 255. QUERY reports print at most 136 characters for
type U and X data values.
Compound Data Items
IMAGE allows the data base designer to specify compound data items. A
compound data item is one that occurs more than once in the same data
entry. Each occurrence of the data item is called a sub-item. Each
sub-item can have a value, and QUERY can locate and update any or all
sub-items. If you update only the first sub-item, QUERY preserves the
existing values of all other sub-items.
Data Set Relations
There are three types of IMAGE data sets: manual master, automatic
master, and detail. Master data sets are related to detail data set
through specific items called search (or key) items. The FORM command
identifies the data set type and search items.
The data base designer can specify one or more sort items. These items
are also identified by the FORM command. As a QUERY user, it is not
necessary to understand the function of sort items. If you want to know
more about data set relations and sort items, refer to the IMAGE
Reference Manual.
Sample Data Base
Figure 1-1 and Figure 1-2 illustrate a sample data base named ORDERS. The
ORDERS data base is used in many examples in this manual. It contains
six data sets. The four master data sets are shown in the center column
and the detail data sets on the sides.
* CUSTOMER contains information about each customer.
* SUP-MASTER contains information about each supplier.
* PRODUCT contains information about each product.
* DATE-MASTER is an index of dates and can be used to retrieve
information by date from the SALES or INVENTORY data sets.
* SALES contains credit and purchase information.
* INVENTORY contains product supply information.
Both figures show a single entry for each data set. Figure 1-1 contains
the data item names, and Figure 1-2 contains a sample of the values in
one entry. The arrows in both figures illustrate the relationship of the
data sets through search items.
![[]](../../pic3k/M010181/F01013c50.gif)
Figure 1-1. ORDERS Data Base Structure
![[]](../../pic3k/M010181/F01023c50.gif)
Figure 1-2. Sample Entry Values
Note: This data base is not meant to be a practical application but
rather is designed to illustrate as many IMAGE/QUERY features as
possible.