Strange behaviour of JDBC query for CHAR column

Question

Hi,
I have a simple table with char type and several records in the table.
create table char_test(str char(50));
insert into char_test values ('abc');
insert into char_test values ('abc ');
insert into char_test values ('abc ');
In JDBC, if I have a query like
PreparedStatement st = conn.prepareStatement("select str from char_test where str = 'abc'");
ResultSet rs = st.executeQuery();
All three rows will be returned.
However, If I use parameter for the PreparedStatment, nothing will be returned if the value of the parameter is passed as "abc".
PreparedStatement st = conn.prepareStatement("select str from char_test where str = ?");
st.setString(1, "abc");
ResultSet rs = st.executeQuery();
Personally, I think this is a bug of Oracle JDBC driver. Could anybody please give me any explanation?
Thanks,
Bill
PS. I'm using Oracle 10g Release 2 DB and ojdbc14.jar under jdk 1.5.

Answer 1

Hello Bill,
Have you solved your problem ?
I have encountered a similar one and found a strange behavior of JDBC driver for PrepareStatement : in some cases, deep in JDBC driver, the parameter values could'nt be convert and are send as null values to the server.
Here are partial driver logs, the first for a program which works fine and the second for one which turns on error.
============================
<record>
<date>2006-09-06T16:27:43</date>
<millis>1157552863218</millis>
<sequence>335</sequence>
<logger>oracle.jdbc.conversion</logger>
<level>FINE</level>
<class>oracle.jdbc.driver.DBConversion</class>
<method>javaCharsToCHARBytes</method>
<thread>10</thread>
<message>DBConversion.javaCharsToCHARBytes(chars[]= (26 bytes):
00 0c 00 65 00 78 00 70 00 73 00 74 00 6f 00 0a 00 73 00 6c
00 65 00 65 00 70 , charOffset=1, bytes[]= (7 bytes):
00 00 00 00 00 00 00 , byteOffset=0, cs=178, nchars=6)</message>
</record>
<record>
<date>2006-09-06T16:27:43</date>
<millis>1157552863218</millis>
<sequence>336</sequence>
<logger>oracle.jdbc.conversion</logger>
<level>FINE</level>
<class>oracle.jdbc.driver.DBConversion</class>
<method>javaCharsToCHARBytes</method>
<thread>10</thread>
<message>DBConversion.javaCharsToCHARBytes(chars, nchars, bytes[], cs): returned 6</message>
</record>
=============================
javaCharsToCHARBytes gets 6 characters OK
=============================
<record>
<date>2006-09-06T16:12:32</date>
<millis>1157551952843</millis>
<sequence>333</sequence>
<logger>oracle.jdbc.conversion</logger>
<level>FINE</level>
<class>oracle.jdbc.driver.DBConversion</class>
<method>javaCharsToCHARBytes</method>
<thread>10</thread>
<message>DBConversion.javaCharsToCHARBytes(chars[]= (40 bytes):
00 26 00 73 00 74 00 6f 00 72 00 61 00 67 00 65 00 5f 00 53
00 74 00 6f 00 72 00 65 00 2e 00 71 00 75 00 65 00 72 00 79 , charOffset=1, bytes[]= (20 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 , byteOffset=0, cs=178, nchars=19)</message>
</record>
<record>
<date>2006-09-06T16:12:32</date>
<millis>1157551952843</millis>
<sequence>334</sequence>
<logger>oracle.jdbc.conversion</logger>
<level>FINE</level>
<class>oracle.jdbc.driver.DBConversion</class>
<method>javaCharsToCHARBytes</method>
<thread>10</thread>
<message>DBConversion.javaCharsToCHARBytes(chars, nchars, bytes[], cs): returned 0</message>
</record>
=============================
javaCharsToCHARBytes gets 0 characters instead of 19
But I am unable to discover the differences between the 2 programs in the JDBC driver usage.
Does this sounds familiar to someone ?
François