Question

QUESTION: can YOU use multiple statements and recordset, which operate simultaneously, using the same connection in a non MULTI THREAD?

I only found this question which interests me, but the answer is not consistent.

JDBC Statement/PreparedStatement per connection

The answer explain the relationship between recordset and statement, which is known to me.

Given that, you can not have multiple recordsets for statement

The answer says that you can have multiple recordsets for connection. But they are not mentioned any other sources.

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I’m asking if it’s possible to loop over the first recordset, then using the same connection (used to generate first recordset) to open another recordset use it looping in iteration. And where is the documentation that define this behavior?

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The situation that interests me is like this, the statement perform tasks simultaneously ins

Connection con = Factory.getDBConn (user, pss, endpoint, etc);
Statement stmt = con.createStatement ();
ResultSet rs = stmt.executeQuery ("SELECT TEXT FROM dba");

while (rs.next ()) {
 rs.getInt (....
 rs.getInt (....
 rs.getInt (....
 rs.getInt (....

 Statement stmt2 con.createStatement = ();
 ResultSet rs2 = stmt2.executeQuery ("iSelect ......");
 while (rs2.next ()) {
 ....
 rs2.close ();
 stm2.close ();

 Statement stmt3 con.createStatement = ();
 ResultSet rs3 = stmt3.executeQuery ("Insert Into table xxx ......");
 ....
 rs3.close ();
 stm3.close ();
}

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To clarify a bit more: with the execution of update in stmt3, you could obtain an error like this:

java.sql.SQLException: There is an open result set on the current connection, which must be closed prior to executing a query.

So you can’t mix SQL in the same connection.

Answer 1

If I understand correctly, you need to work with two (or more) resultsets simmultaneously within a single method.

It is possible, and it works well. But you have to remember a few things:

• Everything you do on each recordset is handled by a single Connection, unless you declare new connections for each Statement (and ResultSet)
• If you need to do a multithreaded process, I suggest you to create a Connection for each thread (or use a connection pool); if you use a single connection in a multithreaded process, your program will hang or crash, since every SQL statement goes through a single connection, and every new statement has to wait until the previous one has finnished.

Besides that, your question needs some clarification. What do you really need to do?