QlikView Reference Manual.pdf - QlikCommunity - QlikView

26 Data Structures
26.1 Data Loading Statements
Data is loaded by load or select statements. Each of these statements generates an internal table. A table can
always be seen as a list of something, each record (row) then being a new instance of the object type and
each field (column) being a specific attribute or property of the object.
Rules:
QlikView does not make any difference between tables generated by a load or a select statement. Hence, if
several tables are loaded, it does not matter whether the tables are loaded by load or select statements or by
a mix of the two.
The order of the fields in the statement or in the original table in the database is arbitrary to the QlikView
logic.
Field names are used in the further process to identify fields and making associations. These are case sensitive.
It is thus often necessary to rename fields in the script. See Renaming Fields (page 369).
26.2 Execution of the Script
For a typical load or select statement the order of events is roughly as follows:
1. Evaluation of expressions
2. Renaming of fields by as
3. Renaming of fields by alias
4. Qualification of field names
5. Mapping of data if field name matches
6. Storing data in an internal table
26.3 System Fields
In addition to the fields extracted from the data source, system fields are also produced by QlikView. These
all begin with "$" and can be displayed in list boxes much like ordinary fields. The system fields which are
typically created during script execution, are primarily used as an aid in document design. The following system
fields can be displayed:
$Table Displays all internal tables loaded by the script. When a single table is
selected, an information symbol will activate in the caption area of the list
box. By clicking here, it is possible to view the table, if it comes from a file.
$Field Displays the fields that are read from the tables. By setting this list box to
Show Frequency in the List Box Properties: General page, it is simple to
detect key fields that occur in several internal tables.
$Fields The numbers in this list box represent the number of fields in different tables.
$FieldNo This list box shows the position of the fields in the tables.
$Rows This list box shows the number of rows in the tables.
$Info If info tables have been included in the document, their names will be displayed
here.
365