On Oct 8, 5:36 am, westmeadboy <[email protected]> wrote:
> I have a TEXT column and I want to match all rows where the value has
> a certain prefix. For example,
>
> WHERE mycol LIKE 'myprefix%'
>
> However, I noticed in some optimization guidelines that this will not
> use the index and instead you should do this:
>
> WHERE mycol >= 'myprefix' AND mycol < 'myprefiy'
>
> Instead of simple A-Z chars, I have a whole variety of UTF-8 chars
> (think chinese characters).
>
> My question is, how to work out the next char in UTF-8?
>
> Is it enough to add one to the codepoint, such as:
>
> String lowerBound = "myprefix";
> int codepoint = Character.codePointAt(lowerBound, lowerBound.length()
> - 1);
> String upperBound = lowerBound.substring(0, lowerBound.length() - 1) +
> Character.toChars(codePoint + 1);
> String sql = "SELECT * FROM mytable WHERE mycol >= '" + lowerBound +
> '" AND mycol < '" + upperBoundPrefix + "'"
>
> ?
see:
http://groups.google.com/group/android-developers/browse_thread/thread/59ab31bab091a171/346727c3527224bd?lnk=gst&q=glob#
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