Schema Name is empty - converting resultset into cachedRowSet

[Vinod]

Hi,

I am converting resultset to a CachedRowSet, which expects a schema name(which is empty).

Code: (Full code is attached)

-------------------------------------------- 

        Connection conn = DriverManager.getConnection("jdbc:h2:mem:TempDB");

        String queryStr = "select '1' from dual";

        PreparedStatement stmt = conn.prepareStatement(queryStr);

        ResultSet rs = stmt.executeQuery();

        

        // following shows that schema name is null

        ResultSetMetaData metaData = rs.getMetaData();

        String schemaName = metaData.getSchemaName(1);

        System.out.println("schemaName=" + schemaName);

        

        // this is the actual call I am making causing NullPointerException

        CachedRowSet sunCachedRowSet = new CachedRowSet();

        sunCachedRowSet.populate(rs);

--------------------------------------------

Output:

-------------------------------------------- 

schemaName=null

Exception in thread "main" java.lang.NullPointerException

at java.lang.String.<init>(Unknown Source)

at sun.jdbc.rowset.RowSetMetaDataImpl.setSchemaName(RowSetMetaDataImpl.java:269)

at sun.jdbc.rowset.CachedRowSet.initMetaData(CachedRowSet.java:680)

at sun.jdbc.rowset.CachedRowSet.populate(CachedRowSet.java:647)

at com.H2SchemaNameEmpty.main(H2SchemaNameEmpty.java:28)

-------------------------------------------- 

I even tried by setting the schema to public: [jdbc:h2:mem:TempDB;SCHEMA=PUBLIC].

To make it work, I modified JdbcResultSetMetaData.getSchemaName to return "PUBLIC" when it is null.

Is there a better way to resolve this.

Thanks,

Vinod

[Thomas Mueller]

Hi,

Thanks a lot for reporting this issue! This is a pretty serious
problem... I didn't know getSchemaName is never supposed to return
null. According to the JDBC specification, the method is supposed to
return an empty string if not applicable, this is what I will do
within H2 for this case. The same for getTableName.

This will be fixed in the next release.

Regards,
Thomas

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[Vinod]

This particular query is executed against dual. Shall it not return PUBLIC instead of empty schema name?

> h2-database+unsubscribe@googlegroups.com.

[Thomas Mueller]

Hi,

As far as I understand, the method is supposed to return the schema
name of the column. Since '1' is a constant and not a column, the
schema name (and table name) is empty. I have tested this with other
databases (PostgreSQL, HSQLDB, and Derby I think) and they work in the
same way.

Regards,
Thomas

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[priyanka priya]

hello sir..

I want to no in h2 how we backup database...for each table..

I want the method to backup each table..

if anyone has answer...please reply....

[Thomas Mueller]

Hi,

> I want to no in h2 how we backup database...for each table..
> I want the method to backup each table..
> if anyone has answer...please reply....

I'm sorry, but nobody should reply to your mail, because you have so
called "hijacked" an email thread. The subject of this email thread is
"Schema Name is empty - converting resultset into cachedRowSet", so
this email thread is about the problem that the schema name is empty.
You, on the other hand, have replied to this email, using the same
subject, but asking a different question that has nothing to do (as
far as I'm aware) of the problem with empty schema name in the result
set meta data. Your question is about backup. So I'm afraid it is bad
if somebody would reply to your mail, because that way other people
might be tempted to so called "hijack" other email threads, and this
would lead to other people not able to find answers for questions that
have been asked before.

To get a reply, I suggest you send a different mail with an
appropriate subject. Or you ask your question at the StackOverflow.com
website.

Kind regards,
Thomas