"DRP" "SQL"-pessimistic lock-prevents dirty data when multiple users are simultaneously operating

1     /**2 * Generate a sequence of the table based on the table name3      * @paramTableName4      * @returnreturns the generated sequence5      */6     //Global Method-Locking7     //public static synchronized int generate (String tableName) {8     //local member Method-locking9     //public synchronized int generate (String tableName) {Ten         //synchronized (this) { One      Public Static intGenerate (String tableName) { A         //pessimistic lock for update using database -String sql = "Select value from t_table_id where Table_name=?" For Update "; -Connection conn =NULL; thePreparedStatement pstmt =NULL; -ResultSet rs =NULL; -         intValue = 0; -         Try { +conn =dbutil.getconnection (); -             //Start a transaction + dbutil.begintransaction (conn); APSTMT =conn.preparestatement (SQL); atPstmt.setstring (1, tableName); -rs =pstmt.executequery (); -             if(!Rs.next ()) { -                 Throw Newruntimeexception (); -             } -Value = Rs.getint ("Value"); invalue++;//self-added - Modifyvaluefield (conn, tableName, value); to             //Commit a transaction + dbutil.committransaction (conn); -}Catch(Exception e) { the e.printstacktrace (); *             //rolling back a transaction $ dbutil.rollbacktransaction (conn);Panax Notoginseng             Throw Newruntimeexception (); -}finally { the Dbutil.close (RS); + Dbutil.close (pstmt); ADbutil.resetconnection (conn);//Resetting The state of the connection the Dbutil.close (conn); +         } -         returnvalue; $}

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"DRP" "SQL"-pessimistic lock-prevents dirty data when multiple users are simultaneously operating