The screenshot overleaf shows the initial QBE page. It contains the following elements:
Criteria columns
An interface to add criteria rows
An interface to add criteria columns
A table selector
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The Multi-Table Query Generator
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The query area
Buttons to update or to execute the query
Choosing Tables
The initial selection includes all the tables. In this example, we assume that the
linked-table infrastructure has been installed into the marc_book database. (See
the section, Single-User Installation, in Chapter 11.) Consequently, the Field selector
contains a great number of fields. For our example, we will work only with the
author and book tables:
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Chapter 13
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We then click Update Query. This refreshes the screen and reduces the number of
fields available in the Field selector. We can always change the table choice later,
using our browser's mechanism for multiple choices in drop-down menus (usually,
control-click).
Column Criteria
Three criteria columns are provided by default. This section discusses the options we
have for editing their criteria. These include options for selecting fields, sorting
individual columns, entering conditions for individual columns, and so on.
Field Selector: Single-Column or All Columns
The Field selector contains all individual columns for the selected tables, plus a
special choice ending with an asterisk (*) for each table, which means all the fields
are selected:
To display all the fields in the author table, we choose `author`.
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