Implement some JDBC methods to support DataGrip

[liutaohua]

The getMaxRow and getMoreResults methods are used to connect IoTDB using DataGrip.

IoTDB-JDBC is not currently supported.

I implemented two methods in which getMoreResults are always returning false instead of throwing an exception.

It looks OK in my local tests so far.

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[jixuan1989]

sounds incorrect...
getMoreResults should return false either:

1. the number of fetched rows >= maxRows
2. no more results from resultSet.

[liutaohua]

When a statement executes multiple SELECTs, the result returned becomes a result with multiple results.
getMoreResults are used to obtain the next result set in this case.

ResultSet resultSet = preparedStatement.executeQuery("select * from root.group_9.d_9 slimit 10;select * from root.group_8.d_8 slimit 10;");

I tested whether the server supports multiple SELECT execution at the same time, and I got this error:

org.apache.iotdb.jdbc.IoTDBSQLException: 401: Error occurred while parsing SQL to physical plan: line 1:41 mismatched input 'select' expecting <EOF>

Obviously the server doesn't support it, so here I think it's correct to always return false.

[HTHou]

Copied from JDBC javaDoc. I agree with @liutaohua .

boolean getMoreResults()
                throws SQLException
Moves to this Statement object's next result, returns true if it is a ResultSet object, and implicitly closes any current ResultSet object(s) obtained with the method getResultSet.
There are no more results when the following is true:


     // stmt is a Statement object
     ((stmt.getMoreResults() == false) && (stmt.getUpdateCount() == -1))
 
Returns:
true if the next result is a ResultSet object; false if it is an update count or there are no more results
Throws:
SQLException - if a database access error occurs or this method is called on a closed Statement