Обсуждение: Re: single quotation confusion
R10 wrote
> i am connecting a postgresql database to a netbeans form , and when i try
> to execute a query which includes a string entered through a Jtextfield
> that contain the special charachter " ' " it reads it as a single
> quotation
> for example if a String txt = "it's cold" and to be inserted into a sql
> query "insert into test values ('"+txt+"')";
> it gives me
> syntax error at or near "s"
>
> any ideas how to solve that problem ??
In short you do not build queries by directly concatenating user-supplied
data. You use a PREPARED STATEMENT with placeholders and then use the
setXXX methods to map the data.
SQL: INSERT INTO test VALUES (?)
Others may be able to provide more concrete suggestions but otherwise find
some books/articles on database programming in Java. This is not a
PostgreSQL specific topic/solution. I've known this for so long now I
really cannot point you to any educational materials.
David J.
--
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David Johnston <polobo@yahoo.com> wrote:
> R10 wrote
>> for example if a String txt = "it's cold" and to be inserted
>> into a sql query "insert into test values ('"+txt+"')";
>> it gives me
>> syntax error at or near "s"
>>
>> any ideas how to solve that problem ??
>
> In short you do not build queries by directly concatenating
> user-supplied data. You use a PREPARED STATEMENT with
> placeholders and then use the setXXX methods to map the data.
>
> SQL: INSERT INTO test VALUES (?)
Yeah, David's suggestion is the way to go. Trying to handle this
in an ad hoc fashion opens you to a class of attack known as "SQL
injection". When concatenating without proper handling of quotes
(which drivers will do for you) you should consider yourself
*lucky* if the worst you have seen is errors.
http://xkcd.com/327/
The above link also illustrates why you shouldn't run the
application under a user ID which has permission to execute DML.
--
Kevin Grittner
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company