Experts for you to explain the basic Java database operations

Data | database | Detailed Java database BASIC operations
1. Java database Operation Basic process
2, a few commonly used important skills:
Scrollable, updated recordsets
Batch Update
Transaction processing

Java database Operation basic process: Get database connection-Execute SQL statement-Process Execution result-release database connection
1. Get the database connection
1) using DriverManager to Access database connection
Example
String classname,url,uid,pwd;
ClassName = "Oracle.jdbc.driver.OracleDriver";
url = "JDBC:ORACLE:THIN:@127.0.0.1:1521:ORASVR;
UID = "System";
PWD = "Manager";
Class.forName (ClassName);
Connection cn = drivermanager.getconnection (URL,UID,PWD);
2 using Jndi (Java naming and directory services)
Example
String Jndi = "jdbc/db";
Context CTX = (context) new InitialContext (). Lookup ("java:comp/env");
DataSource ds = (DataSource) ctx.lookup (JNDI);
Connection cn = Ds.getconnection ();
More used in JSP

2. Execute SQL statement
1 using statement to execute SQL statements
String SQL;
Statement sm = cn.createstatement ();
Sm.executequery (SQL); Execute a Data query statement (SELECT)
Sm.executeupdate (SQL); Execute Data UPDATE statements (delete, update, insert, DROP, etc.) Statement.close ();
2 using PreparedStatement to execute SQL statements
String SQL;
sql = "INSERT into user (Id,name) VALUES (?,?)";
PreparedStatement PS = cn.preparestatement (SQL);
Ps.setint (1,XXX);
Ps.setstring (2,XXX);
...
ResultSet rs = Ps.executequery (); Inquire
int c = Ps.executeupdate (); Update

3, processing the results of implementation
Query statement that returns a recordset resultset
UPDATE statement, returning a number that represents the number of records affected by the update
The method of ResultSet
1, Next (), move the cursor back one row, or False if successful return true;
2, GETINT ("id") or getsting ("name"), returns the value of a field under the current cursor

4, Release the connection
Cn.close ();
Generally, close the resultset first, then close the statement (or PreparedStatement), and finally close the connection

Scrollable, updated recordset
 1, creating scrollable, updated Statement
  statement sm = cn.createstatement (resultset.type_ SCROLL_ENSITIVE,RESULTSET.CONCUR_READ_ONLY);
   The ResultSet that statement obtains is scrollable
 2, specifying parameters when creating PreparedStatement
   Preparedstatemet PS = cn.preparestatement (sql,resultset.type_scroll_insensitive,resultset.concur_read_only);

  resultset.absolute (9000);   
Batch update
 1, Statement
  statement sm = Cn.createstatement ();
  sm.addbatch (SQL1);
  sm.addbatch (SQL2);
  ..
  sm.executebatch ()
   A statement object that can execute multiple SQL statements after a batch update. The multiple statements can be delete, update, insert, or both
 2, PreparedStatement
  preparedstatement PS = Cn.preparedstatement (SQL);
  {
   ps.setxxx (1,xxx);
   
   ps.addbatch ();
  }
  ps.executebatch ();
   A PreparedStatement, you can put an SQL statement, transform the parameters to perform multiple times, one update.

Handling of transactions
1, turn off the automatic submission of connection
Cn.setautocommit (FALSE);
2. Execute a series of SQL statements
Important: Before executing each new SQL statement, the last statement (or Preparedstatemet) that executed the SQL statement must first close
Statement SM;
SM = cn.createstatement (insert into user ...);
Sm.executeupdate ();
Sm.close ();

SM = cn.createstatement ("INSERT INTO corp ...");
Sm.executeupdate ();
Sm.close ();

3. Submit
Cn.commit ();
4, if an exception occurs, then rollback
Cn.rollback ();