Databases Reference
In-Depth Information
Table information
When hovering the mouse cursor over a table header, a tool tip is shown to display
the name of the table and the number of rows, fields, and key fields. This can be used
to do a quick sanity check on the loaded data. Optionally, when a comment is set for
the table (using the
COMMENT TABLE
script statement), the corresponding comment is
also shown in the tool tip. For example, the following screenshot shows the tool tip
for the
Aircraft Types
table:
Field information
When the mouse cursor hovers over a field name within a table, it gets even
more interesting.
The following information is shown in the previous screenshot:
• The name of the field. Optionally, if the field is a key field, a qualifier is
shown enclosed in square brackets. This qualifier indicates the following
levels of key quality:
° [Perfect Key] indicates that every row contains a key value, and that
all of these key values are unique. At the same time, the field's subset
ratio is 100 percent. This qualifier should be seen in dimension tables,
where every key should uniquely identify a single record.
° [Primary Key] indicates that all key values are unique, but not
every row contains a key value or the field's subset ratio is less
than 100 percent.
° [Key] indicates that the key is not unique. This qualifier is usually
seen in fact tables, where the same dimension value may be
associated with many different facts.
