Adv Java - [JDBC: Resultset Types]

♠ Posted by Unknown in at 01:44

JDBC Resultsets

Before JDBC 2.1, a ResultSet object created by executing a statement was, by default, forward-only scrollable. That is, we could traversse through the resultset using the next() method only. next() returns false when the last record is reached, and no more details can then be retrieved.


The JDBC 2.1 API (included in the J2SE 1.2 onwards) provides more flexible means of accessing results from ResultSet objects. These enhancement are categorized into the following:

  1. Scrollable resultsets :

The JDBC 2.1 ResultSet objects are scrollable resultsets have the ability to move the cursor backwards, and also support absolute positioning of the cursor at a particular row in the4 resultset.

The java.sql.ResultSet interface specifies three types of resultsets:
1. TYPE_FORWARD_ONLY – A resultset of this type supports forward-scrolling only.
2. TYPE_SCROLL_INSENSITIVE – A resultset of this type supports scrolling in both directions.
3. TYPE_SCROLL_SENSITIVE – A resultset of this type is sensitive to updates made to the data after the resultset has been populated. For instance, if your query returns 10 rows, and if another application removes two of the rows, your resultset will only have 8 rows. The same happens for inserts/updates too.

  1. Scroll sensitivity :

The JDBC 2.1 APT also specifies scroll-sensitive and scroll-insensitive resultsets. A scroll insensitive resultset represents a static snapshot of the results when the query was made. On the other hand, a scroll-sensitive resultset is sensitive to changes made to the data after the query has been executed, thus providing a dynamic view of the data as it changes.

  1. Updatable resultsets :

By default, resultsets are read-only. That is, contents of the resultset are read-only and connot be changed. The JDBC 2.1 API also introduces updateable resultsets. When a resultset is updated, the update operation also updates the original data corresponding to the resultset.

The java.sql.ResultSet interface specifies two constants to indicate whether the resultset is read-only of updateable:

  1. CONCUR_READ_ONLY – using this type of resultset, we cannot use any of the methods discussed below to insert, update or delete rows.
  2. CONCUR_UPDATABLE – with this constant, we can insert, update, or delete rows in the resultset.

0 comments:

Post a Comment