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|How do you do a bitwise compare in select where?|
| 5:45 am on Nov 18, 2010 (gmt 0)|
I'm trying to select from a table by doing a bitwise compare but it does not work. Here is the sql select statement i have in my php script...
$Mask = implode($aom);
$sql = "SELECT * FROM dbtable WHERE ('".$Mask."' & Code)";
Basically; SELECT * FROM dbtable WHERE ('10100000000000' & Code)
$Mask is a 14 character string of ones and zeros i.e. "10100000000000"
Code is also a 14 character string field in the table similar to $Mask.
I want to do a bitwise compare of $Mask & Code with the "And" operator to test if Bits that are set in both $a and $b are set or true. if so, then get the record.
Like i said, the way i have it does not work. Is it because you can't do a bitwise compare on two strings?
A little help would be appreciated.
| 8:24 pm on Nov 19, 2010 (gmt 0)|
I don't do a lot with bitwise operators, but I think your query needs to look like this:
$sql = "SELECT * FROM dbtable WHERE '".$Mask."' & Code = '".$Mask."'";
| 9:45 pm on Nov 19, 2010 (gmt 0)|
While your solution won't work, you reminded me that ".$Mask. & code" must compare to something. Not "= .$Mask." but "<> '00000000000000'" for the where to work properly.
So the sql statement, i think, should look like this...
$Mask = '10100000000000';
$sql = "SELECT * FROM dbtable WHERE '".$Mask."' & code <> '"."00000000000000"."'";
As long as the bitwise operation of ".$Mask. & code" do not result in all zeros, i'll get records.
BTW, how did you get the php code to display in color?
| 11:29 pm on Nov 19, 2010 (gmt 0)|
unfortunately, it does not work because is appears the the bitwise and/or operators only work on integers not strings like you can in php.
| 8:58 pm on Nov 23, 2010 (gmt 0)|
What happens if you take out the single quotes? MySQL should then treat those as integers.
If your `Code` field is a VARCHAR (or other string) use the Cast functions [dev.mysql.com] to get it to the right type.
| 11:47 pm on Nov 23, 2010 (gmt 0)|
I give it try asap.
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