TYPE_SCROLL_SENSITIVE
in [Java Programming]
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From: Arne Vajhøj on 4 Jul 2010 15:09 On 28-06-2010 23:32, gk wrote: > On 29 June, 03:04, Arne Vajh�j<a...(a)vajhoej.dk> wrote: >> On 28-06-2010 07:52, gk wrote: >>> On Jun 28, 4:26 pm, gk<src...(a)gmail.com> wrote: >>>> On Jun 28, 3:55 pm, RedGrittyBrick<RedGrittyBr...(a)spamweary.invalid> >>>> wrote: >>>>> On 28/06/2010 10:41, gk wrote: >>>>>> please look at the doc for ResultSet >>>>>> http://java.sun.com/j2se/1.4.2/docs/api/java/sql/ResultSet.html#TYPE_... >> >>>>>> TYPE_SCROLL_SENSITIVE >>>>>> public static final int TYPE_SCROLL_SENSITIVEThe constant indicating >>>>>> the type for a ResultSet object that is scrollable and generally >>>>>> sensitive to changes made by others. >> >>>>>> What it means by "generally sensitive to changes made by others" ? I >>>>>> don't get this part. >> >>>>> For general questions of this sort, you'll often get an adequate answer >>>>> by searching using Google or some other search engine: >> >>>>> http://en.wikipedia.org/wiki/Cursor_%28databases%29 >> >>>>> "Scrollable cursors can potentially access the same row in the result >>>>> set multiple times. Thus, data modifications (insert, update, delete >>>>> operations) from other transactions could have an impact on the result >>>>> set. A cursor can be SENSITIVE or INSENSITIVE to such data >>>>> modifications. A sensitive cursor picks up data modifications impacting >>>>> the result set of the cursor, and an insensitive cursor does not." >> >>>>> Note that this is really an SQL question, more than a Java question. >>>>> Sometimes you'll get more relevant answers to DBMS-specific SQL >>>>> questions in an appropriate database newsgroup or forum. >>>> Thanks . your post was very much helpful.- Hide quoted text - >>> However , how does it different from attribute CONCUR_UPDATABLE ? >> >>> If we use CONCUR_UPDATABLE as a ResultSet attribute that too also >>> picks up the updated data ...is not it ? why do we need the >>> SENSITIVE attribute then ? >> >> I am far from a JBDB expert but I read the docs as: >> >> TYPE_SCROLL_INSENSITIVE - I can scroll forward and backward& I will not >> see changes done by others >> TYPE_SCROLL_SENSITIVE - I can scroll forward and backward& I will see >> changes done by others >> CONCUR_READ_ONLY - I can not update the result set >> CONCUR_UPDATABLE - I can update the result set >> >> So the difference is between me and other. > > What do you mean by update the ResultSet ? we take the results out of > the ResultSet. we do rs.getString("columnName") to extract the > result. We don't update ResultSet really. > > I don't understand why you are saying updating ResultSet. > > do we do that ever ? The following two methods more or less do the same thing: private static void update1(Connection con) throws SQLException { Statement stmt = con.createStatement(); stmt.executeUpdate("UPDATE fun SET txt = 'XX' WHERE id = 2"); stmt.close(); } private static void update2(Connection con) throws SQLException { Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE); ResultSet rs = stmt.executeQuery("SELECT id,txt FROM fun WHERE id = 2"); rs.next(); rs.updateString(2, "BB"); rs.updateRow(); rs.close(); stmt.close(); } No - I don't think the construct is much used in Java & JDBC. But it is used a lot on ASP & ADO. Someone must have said "so ein ding mussen wir auch haben". Arne |