The IntervalMatch prefix is used to create a table matching discrete numeric values to one or more numeric intervals.
It must be placed before a Load or Select (SQL)statement that loads the intervals. The field containing the discrete data points (Time in the example below) must already have been loaded into QlikView before the statement with the IntervalMatch prefix. The prefix does not by itself read this field from the database table. The prefix transforms the loaded table of intervals to a table that contains an additional column: the discrete numeric data points. It also expands the number of records so that the new table has one record per possible combination of discrete data point and interval.
The intervals may be overlapping and the discrete values will be linked to all matching intervals.
matchfield is the field containing the discrete numeric values to be linked to intervals.
loadstatement or selectstatement must result in a two-column table, where the first field contains the lower limit of each interval and the second field contains the upper limit of each interval. The intervals are always closed, i.e. the end points are included in the interval. Non-numeric limits render the interval to be disregarded (undefined).
There is also an extended syntax of IntervalMatch including one or several additional key fields. See IntervalMatch (Extended Syntax).
Example:
In the two tables below, the first one defines the start and end times for the production of different orders. The second one lists a number of discrete events. By means of the IntervalMatch prefix it is possible to logically connect the two tables in order to find out e.g. which orders were affected by disturbances and which orders were processed by which shifts.
OrderLog
Start
End
Order
01:00
03:35
A
02:30
07:58
B
03:04
10:27
C
07:23
11:43
D
EventLog
Time
Event
Comment
00:00
0
Start of shift 1
01:18
1
Line stop
02:23
2
Line restart 50%
04:15
3
Line speed 100%
08:00
4
Start of shift 2
11:43
5
End of production
First load the two tables as usual, then link the field Time to the time intervals defined by the fields Start and End:
SQL SELECT * FROM OrderLog;
SQL SELECT * FROM Eventlog;
IntervalMatch ( Time ) SQL SELECT Start, End FROM OrderLog;
The following table box can now be created in QlikView:
