An easily overlooked result of the Oracle database fuzzy query statement: the problem of empty records

An easily overlooked result of the Oracle database fuzzy query statement: the problem of empty records
the
reason:
the
Use the SQL statement as follows:
the
select count(*) from test;
the
The result is 1390.
select count(*) from test where bb not like ‘%disable%’
the
The result is 393.
the
During the actual browsing process, it is found that the non-disabled result set must exceed 393 records.
the
process:
the
1. First suspect the character set problem, maybe the client character set does not match the server character set.
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After using the above SQL statement on someone else’s machine, repeated and similar substitutions, the results are the same.
the
2. I still suspect that it is a problem with the character set, and I am almost crazy because I have not found the real cause of the problem.
the
3. I accidentally found that many of the bb fields are empty. After careful analysis, I found that bb not like ‘%disabled%’ will not match empty records, so I changed it to
the
select count(*) from test where bb not like ‘%disable%’ or bb is null
the
The result is 1356.
the
Conclusion:
the
Because fuzzy matching is not used frequently, it will lead to sloppy use, which will eventually lead to manpower going crazy.

the
the
Author noodle123