Last week a coworker had a document loaded with data from a
database job log table. It was over a million rows of log data that various
batch jobs had written into. She wanted to select the rows that represented the
start time of jobs and also the rows that represented the end time of jobs.
Either one by itself would be easy. We knew that the LOGMESSAGE column contains
the text ‘JOB START [‘ for log messages posted by jobs when they start up and
the column contains the text ‘FINISH STATUS [‘ for messages posted by jobs when
they end. To select either of those types of rows you would just click a
listbox for the LOGMESSAGE column and start typing the text and QlikView would
automatically select the rows. But, selecting both start message and end
messages – that is different, how to do that?
The answer is to use an advanced search expression. For this
example, you click on the LOGMESSAGE listbox and then start typing this: =wildmatch(LOGMESSAGE,' *JOB START [*','*FINISH
STATUS [*')
As soon as you type the equal sign, QlikView knows you are
entering an advanced search expression. QlikView then tests the WildMatch function for
each possible value of LOGMESSAGE and if the function is true then the column value
is shown in the listbox and when you click [enter] the values are selected. It
worked great for our log data problem- all of the start and end log messages
were selected and shown in the chart along with their job start timestamps and
job end timestamps.
The asterisks in the WildMatch expression are wild card
characters that represent any series of characters. We could have added other
wildcard matching strings too if we needed them. For example, if the job end
messages had two different text layouts then we could have used the matching
text to select both types of end messages. Despite the fact that the WildMatch
expression contains the column name, LOGMESSAGE, it could be used with any of
the columns or fields in the document and it would select the values that are associated
with the LOGMESSAGE start and end messages.
★★★
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