Java Reference
In-Depth Information
Note that the
commit()
method is called only if all transaction statements were
processed successfully. If any of them fail, the
successFlag
is equal to
false
,
which would cause the
rollback()
method to be called instead. In the solution to
this recipe, the second call to
insertRecord()
attempts to insert a
NULL
value into
the
RECIPE.ID
column, which is not allowed. Therefore, that insert fails and
everything, including the previous insert, gets rolled back.
13-8. Creating a Scrollable ResultSet
Problem
You have queried the database and obtained some results. You want to store those res-
ults in an object that will allow you to traverse forward and backward through the res-
ults, updating values as needed.
Solution
Create a scrollable
ResultSet
object and then you will have the ability to read the
next, first record, last, and previous record. Using a scrollable
ResultSet al
lows
the results of a query to be fetched in any direction so that the data can be retrieved as
needed. The following example method demonstrates the creation of a scrollable
Res-
ultSet
object:
private static void queryDbRecipes(){
String sql = "SELECT ID, RECIPE_NUMBER, RECIPE_NAME,
DESCRIPTION " +
"FROM RECIPES";
try(PreparedStatement pstmt
=conn.prepareStatement(sql,
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY);
ResultSet rs = pstmt.executeQuery()) {
rs.first();
System.out.println(rs.getString(2) + ": "
