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Re: JDBCR4 question -- Checking the syntax of a query without crashing the JVM



fixed

James

There's a very nice API for checking SQL syntax - Syntax Check SQL Statement (QSQCHKS) <http://pic.dhe.ibm.com/infocenter/iseries/v7r1m0/topic/apis/qsqchks.htm>

I went to the API Finder, typed SQL in the name box, hit enter and got a lot of things - at the bottom was this.

HTH
Vern

On 2/25/2014 1:18 PM, James H. H. Lampert wrote:
My Fellow Midrange Geeks and Geekettes:

One of the features I've put into my project is the ability to
incorporate a user-specified WHERE clause into the generated WHERE
clauses of my queries, in order to filter the records accessed.

But if the user uses this feature to insert garbage into the WHERE
clause (e.g., "WHERE FOO = 'BAR'," with no FOO field in the file), it
results in a series of bad JDBC calls that crashes JDBC and the JVM,
requiring the user to sign off and sign back on.
Space offset X'00000000' or X'00008000300149F0' is outside current limit
for object <jobname> <user> <jobnum>.
I'd like to be able to catch the bad query before this happens. Is there
a way to do this?

It seems, running it in the debugger, that when the query gets executed
rs1 = jdbc_ExecQryCS( conn : %UCS2('Select * '
+ ' from ' + %TRIM(QUALTBL) + ' WHERE ((')
+ %TRIM(WHERECLAUSE1) + %UCS2(') ') + %TRIM(ORWHERE1)
+ %UCS2(') AND (') + %UCS2(%TRIM(ADDLWHERE))
+ %UCS2(') ORDER BY ' + ORDERBY));
(jdbc_ExecQryCS being a UCS2-parameter [so we can process Unicode
keyfields], scrollable result set version of jdbc_ExecQry), RS1 comes
back as null (0), and an RNX0301,
Java exception received when calling Java method.
appears in the joblog, with
Cause . . . . . : RPG procedure JDBC_EXECQ in program AQUESTVIEW/JDBCR4QV
received Java exception "java.sql.SQLException: [SQL0206] Column FOO not in
specified tables." when calling method "executeQuery" with signature
"(Ljava.lang.String;)Ljava.sql.ResultSet;" in class "java.sql.Statement".
Now assuming I recognize, and respond to, the null result set I get, am
I going to have to insert an ExceptionClear somewhere, in order to keep
the next call from crashing the JVM? For reference, here is the
aforementioned "jdbc_ExecQryCS":
P JDBC_ExecQryCS B export
D JDBC_ExecQryCS PI like(ResultSet)
D conn like(Connection) const
D sql 32767C varying const options(*varsize)
D stmt s like(Statement)
D temp s like(ResultSet)
D rs s like(ResultSet)
/free
jdbc_begin_object_group(50);

monitor;
stmt = createStatement2( conn: 1005: 1007); // 1007 read-only
temp = executeQuery( stmt : new_StringC(sql));
jdbc_end_object_group(temp: rs);
on-error;
jdbc_end_object_group();
return *NULL;
endmon;

return rs;
/end-free
P E
(Not too different from Scott's original jdbc_ExecQry.)

--
JHHL






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