java - Why does deletion of rows from one table work, but not from another? -

i trying delete rows tables. code in first program succeeds in deleting row. code in second, similar program deletes 0 rows.

however, when issuing same delete command sql command line tool, reports 1 row being deleted.

first program:

package oracle;  import java.sql.drivermanager; import java.sql.connection; import java.sql.preparedstatement; import java.sql.sqlexception; import java.text.dateformat; import java.text.simpledateformat;  public class jdbcpreparedstatementinsertexample {      private static final string db_driver      = "oracle.jdbc.driver.oracledriver";     private static final string db_connection  = "jdbc:oracle:thin:@localhost:1521:xe";     private static final string db_user        = "system";     private static final string db_password    = "datta123";      public static void main(string[] argv) {          try {              insertrecordintotable();          } catch (sqlexception e) {              system.out.println(e.getmessage());          }      }      private static void insertrecordintotable() throws sqlexception {          connection dbconnection = null;         preparedstatement preparedstatement = null;           try {             dbconnection = getdbconnection();             system.out.println("oracle database connected:\n");             string deletesql = "delete dbuser username = ?";             preparedstatement = dbconnection.preparestatement(deletesql);             preparedstatement.setstring(1, "avi");             // execute delete sql stetement             int = preparedstatement.executeupdate();             system.out.println("success:"+i);          } catch (sqlexception e) {              system.out.println(e.getmessage());          } {              if (preparedstatement != null) {                  preparedstatement.close();             }              if (dbconnection != null) {                  dbconnection.close();             }         }     }      private static connection getdbconnection() {          connection dbconnection = null;          try {              class.forname(db_driver);          } catch (classnotfoundexception e) {              system.out.println(e.getmessage());          }          try {              dbconnection = drivermanager.getconnection(                         db_connection, db_user,db_password);             return dbconnection;          } catch (sqlexception e) {              system.out.println(e.getmessage());          }          return dbconnection;      } } 

output:

oracle database connected: success:1

second program:

package oracle;  import java.sql.drivermanager; import java.sql.connection; import java.sql.preparedstatement; import java.sql.sqlexception; import java.text.dateformat; import java.text.simpledateformat;  public class jdbcpreparedstatementinsertexample {      private static final string db_driver     = "oracle.jdbc.driver.oracledriver";     private static final string db_connection = "jdbc:oracle:thin:@localhost:1521:xe";     private static final string db_user       = "system";     private static final string db_password   = "datta123";      public static void main(string[] argv) {          try {              insertrecordintotable();          } catch (sqlexception e) {              system.out.println(e.getmessage());          }      }      private static void insertrecordintotable() throws sqlexception {          connection dbconnection = null;         preparedstatement preparedstatement = null;           try {             dbconnection = getdbconnection();             system.out.println("oracle database connected:\n");             string deletesql = "delete admin name = ?";             preparedstatement = dbconnection.preparestatement(deletesql);             preparedstatement.setstring(1, "datta");             // execute delete sql stetement             int = preparedstatement.executeupdate();             system.out.println("success:"+i);          } catch (sqlexception e) {              system.out.println(e.getmessage());          } {              if (preparedstatement != null) {                 preparedstatement.close();             }              if (dbconnection != null) {                 dbconnection.close();             }         }     }      private static connection getdbconnection() {          connection dbconnection = null;          try {              class.forname(db_driver);          } catch (classnotfoundexception e) {              system.out.println(e.getmessage());          }          try {              dbconnection = drivermanager.getconnection(                         db_connection, db_user,db_password);             return dbconnection;          } catch (sqlexception e) {              system.out.println(e.getmessage());          }          return dbconnection;     } } 

output:

oracle database connected: success:0

but command line tool, same query executed successfully:

sql> delete admin name='datta';  1 row deleted.