 | | | Subject: ascii nulls in regex 's | Subject: ascii nulls in regex 's 2007-10-26 - By Wagner, Chris (GEAE, CBTS)
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Greetings all. I've run into something annoying that doesn't seem to be
in the MySQL manual. I have fields of type varchar that contain null
characters, chr(0). I need to find these for error reporting however
MySQL seems to regard them as string terminators. A regex stops parsing
on encountering the null. The fields should only contain DNS legal
characters so I used a simple regex to find exceptions. However the
nulls totally blow it up:
mysql> SELECT "comprm1 " REGEXP "^[a-z0-9.-]+$";
+-- ---- ---- ---- ---- ---- ---- --+
| "comprm1 " REGEXP "^[a-z0-9.-]+$" |
+-- ---- ---- ---- ---- ---- ---- --+
| 0 |
+-- ---- ---- ---- ---- ---- ---- --+
1 row in set (0.00 sec)
mysql> SELECT "comprm1\0 " REGEXP "^[a-z0-9.-]+$";
+-- ---- ---- ---- ---- ---- ---- ----+
| "comprm1\0 " REGEXP "^[a-z0-9.-]+$" |
+-- ---- ---- ---- ---- ---- ---- ----+
| 1 |
+-- ---- ---- ---- ---- ---- ---- ----+
1 row in set (0.00 sec)
They also don't fall under the [:cntrl:] class!
mysql> SELECT "comprm1\0 " REGEXP "[[:cntrl:]]";
+-- ---- ---- ---- ---- ---- ---- --+
| "comprm1\0 " REGEXP "[[:cntrl:]]" |
+-- ---- ---- ---- ---- ---- ---- --+
| 0 |
+-- ---- ---- ---- ---- ---- ---- --+
1 row in set (0.00 sec)
I can use LIKE to find them but I'ld prefer to use a single concise
regex.
mysql> SELECT "comprm1\0 " LIKE "%\0%";
+-- ---- ---- ---- ---- ---+
| "comprm1\0 " LIKE "%\0%" |
+-- ---- ---- ---- ---- ---+
| 1 |
+-- ---- ---- ---- ---- ---+
1 row in set (0.00 sec)
Any ideas?
--
Chris Wagner
CBTS
GE Aircraft Engines
Chris.Wagner@(protected)
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