LocalDateTime and SQL Server JDBC 4.2 driver

I don't know what I'm doing wrong here.

You're not doing anything wrong. You have encountered a deficiency in Microsoft's JDBC driver for SQL Server prior to version 7.1.0, discussed here.

If you are using mssql-jdbc version 7.1.0 or later then you can use getObject(x, LocalDateTime.class) as expected.

For mssql-jdbc versions prior to 7.1.0, as others have suggested, you'll need to retrieve a Timestamp and convert it to a LocalDateTime. However, be aware that the simplistic solution ...

LocalDateTime dateTime = resultSet.getTimestamp("date_from").toLocalDateTime()

... will corrupt certain date/time values if the default time zone for the JVM observes Daylight Saving Time, a.k.a. "Summer Time". For example,

// time zone with Daylight Time
TimeZone.setDefault(TimeZone.getTimeZone("America/Edmonton"));

// test environment
Statement st = conn.createStatement();
st.execute("CREATE TABLE #tmp (id INT PRIMARY KEY, dt2 DATETIME2)");
st.execute("INSERT INTO #tmp (id, dt2) VALUES (1, '2018-03-11 02:00:00')");
ResultSet rs = st.executeQuery("SELECT dt2 FROM #tmp WHERE id=1");
rs.next();

// test code
LocalDateTime x = rs.getTimestamp("dt2").toLocalDateTime();  // bad

System.out.println(x.toString());

will print "2018-03-11T03:00". Note that the time is "03:00", not "02:00".

Instead, you'll need to retrieve the Timestamp as UTC and then convert it into a LocalDateTime for UTC, thus removing the time zone component

// time zone with Daylight Time
TimeZone.setDefault(TimeZone.getTimeZone("America/Edmonton"));

// test environment
Statement st = conn.createStatement();
st.execute("CREATE TABLE #tmp (id INT PRIMARY KEY, dt2 DATETIME2)");
st.execute("INSERT INTO #tmp (id, dt2) VALUES (1, '2018-03-11 02:00:00')");
ResultSet rs = st.executeQuery("SELECT dt2 FROM #tmp WHERE id=1");
rs.next();

// test code
Timestamp ts = getTimestamp("dt2", Calendar.getInstance(TimeZone.getTimeZone("UTC")));
LocalDateTime x = LocalDateTime.ofInstant(ts.toInstant(), ZoneId.of("UTC"));  // good

System.out.println(x.toString());

which prints "2018-03-11T02:00".

This is because the Microsoft SQL Server JDBC driver implementation of resultSet.getObject(...) cannot auto convert from java.sql.Timestamp to LocalDateTime.

As a workaround you can get the value as java.sql.Timestamp and then convert java.sql.Timestamp to LocalDateTime by using: java.sql.Timestamp.toLocalDateTime()

LocalDateTime dateTime = resultSet.getTimestamp("date_from").toLocalDateTime()