The problem is that our marker ':' can be used in SQL although, as far
as I can tell, only within embedded single or double quotes like this:
Select "fif:fi'ef" from 'sefti:iend' where "sdsd:ske" =:id and age
>:age and addr = :addr
Which we need to convert to
Select "fif:fi'ef" from 'sefti:iend' where "sdsd:ske" =? and age >?
and addr = ?
The following algorithm was suggested by Don Clare and seems to work:
final static String Q_MARK = "?";
final static String SQL_QUOTED_SEQUENCE_PATTERN = "(['\\\"]).*?\\1";
final static String SQL_HOST_VARIABLE_PATTERN = "(\\W):(\\w*)";
public static String replaceHostVariables(String inStr) {
ArrayList<Integer> indices = new ArrayList<Integer>();
indices.add(0);
StringBuffer sb = new StringBuffer();
Pattern p =
Pattern.compile(SQL_QUOTED_SEQUENCE_PATTERN,Pattern.DOTALL);
Matcher m = p.matcher(inStr);
while (m.find()) {
indices.add(m.start());
indices.add(m.end());
}
indices.add(inStr.length());
Iterator<Integer> i = indices.iterator();
p = Pattern.compile(SQL_HOST_VARIABLE_PATTERN,Pattern.DOTALL);
while (i.hasNext()) {
m.usePattern(p);
m.region(i.next(), i.next());
while (m.find()) {
m.appendReplacement(sb, m.group(1) + Q_MARK);
}
}
m.appendTail(sb);
return sb.toString();
}
EJB supports named parameters as part of EJBQL but only positional
parameters for native queries.
I am really torn here. I see the value in named parms but wonder if the
DAS should have to work so hard to provide it when this is not yet part
of the SQL standard.
Thanks,
--Kevin
Jeremy Boynes wrote:
There are a lot of benefits to named parameters and users seem to like
them - it would be a shame to see them go.
How complex would a parser be? Wouldn't it just need to handle the
distinction between string values/comments etc. and SQL text? That
would be a lot simpler than parsing the actual SQL.
What does EJB3 do for native queries? Can we do something like that
(or better)?
--
Jeremy
On 6/13/06, Kevin Williams <[EMAIL PROTECTED]> wrote:
DAS has a problem with its attempt to support named parameters in SQL
as in:
command = Factory.createCommand ("select * from Customer where
Customer.id = :id")
command.setParm("id", 500);
We have been using a colon as the parameter marker and this works well
since we can do a simple scan of the select statement to find the named
parameter markers and replace them with '?'. Unfortunately, a scan is
not sufficient when the SQL uses colons as part of the statement itself,
like in an embedded timestamp. To pluck out the parameter markers in
these more complicated cases requires a parser and, IMO, the DAS has no
business parsing SQL.
So, what I propose is to remove support for named parameters altogether
and leave clients with indexed parameter access like this:
command = Factory.createCommand ("select * from Customer where
Customer.id = ?")
command.setParm(1, 500);
Any opinions?
Thanks,
--Kevin
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