ResultSet problem in JDBC
Hi all,
I am writing a Java program using postgres. When I run my program, I got the following error message:
Exception in thread "main" org.postgresql.util.PSQLException: Can't infer the SQL type to use for
an instance of org.postgresql.jdbc4.Jdbc4ResultSet. Use setObject() with an explicit Types value to specify the type to use.
at org.postgresql.jdbc2.AbstractJdbc2Statement.setObject(AbstractJdbc2Statement.java:1772)
at org.postgresql.jdbc3g.AbstractJdbc3gStatement.setObject(AbstractJdbc3gStatement.java:37)
at org.postgresql.jdbc4.AbstractJdbc4Statement.setObject(AbstractJdbc4Statement.java:46)
at Cracking.testMethod(Cracking.java:619)
at GetConnection.main(GetConnection.java:97)
My code that caused this problem is:
Statement st = c.createStatement();
ResultSet r = st.executeQuery("select unnest(col0) from relation2_col1 where keyValue<500");
PreparedStatement sql = c.prepareStatement( "SELECT col1 FROM relation2 WHERE col0 IN ?");
sql.setObject(1, r);
ResultSet result = sql.executeQuery();
I am using Eclipse, and there is no warning for this code.
Can't a result set be used in another query? How do I correct it?
Import Notes
Reply to msg id not found: 1503640621.914211291266514731.JavaMail.root@mail-01.cse.ucsc.edu
On 02/12/10 13:14, Zhipan Wang wrote:
Statement st = c.createStatement();
ResultSet r = st.executeQuery("select unnest(col0) from relation2_col1
where keyValue<500");
PreparedStatement sql = c.prepareStatement( "SELECT col1 FROM relation2
WHERE col0 IN ?");
sql.setObject(1, r);
ResultSet result = sql.executeQuery();
You appear to be trying to implement a subquery client-side. Why not
just use:
PreparedStatement sql = c.prepareStatement(
"SELECT col1 FROM relation2 WHERE col0 IN "+
"(SELECT unnest(col0) from relation2_col1 where keyValue<500"
);
? It's hard to know whether the above is correct because you've failed
to provide your schema, but something along those lines seems to fit
your intent from the code above.
I am using Eclipse, and there is no warning for this code.
No, Eclipse can't know the details of how every JDBC driver works.
Can't a result set be used in another query? How do I correct it?
Either build an array with the contents of the resultset and pass that,
or avoid the weirdness by using a subquery directly.
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