Oracle JDBC

1、CONNECT

Class.forName("org.postgresql.Driver");
Connection connection = null;
connection = DriverManager.getConnection(
"jdbc:oracle:thin:@localhost:1521:mkyong","username","password");
connection.close();

JDBC & Statement

2、STATAMENT

The “Statement” interface is used to execute a simple SQL statement with no parameters. For create, insert, update or delete statement, uses “

Statement.executeUpdate(sql)

“; select query, uses “

Statement.executeQuery(sql)

“.

3、 To issue a create statement, calls the S

tatement.execute()

method like this :

Statement statement = dbConnection.createStatement();
// execute create SQL stetement
statement.execute(createTableSQL);

4、To issue a insert statement, calls the

Statement.executeUpdate()

method like this :

Statement statement = dbConnection.createStatement();
// execute the insert SQL stetement
statement.executeUpdate(insertTableSQL);

5、To issue a update statement, calls the

Statement.executeUpdate()

method like this :

Statement statement = dbConnection.createStatement();
// execute the update SQL stetement
statement.executeUpdate(updateTableSQL);

6、 To issue a delete statement, calls the

Statement.executeUpdate()

method like this :

Statement statement = dbConnection.createStatement();
// execute the delete SQL stetement
statement.executeUpdate(deleteTableSQL);

7、 To issue a select query, calls the

Statement.executeQuery

method like this :

String selectTableSQL = "SELECT USER_ID, USERNAME from DBUSER";
Statement statement = dbConnection.createStatement();
ResultSet rs = statement.executeQuery(selectTableSQL);
while (rs.next()) {
String userid = rs.getString("USER_ID");
String username = rs.getString("USERNAME");
}

8、批量处理数据；

Here’s an example to show you how to insert few records in batch process, via JDBC

Statement

.
Batch Update is not limit to Insert statement, it’s apply for Update and Delete statement as well.

insertSQL

String insertTableSQL1 = "INSERT INTO DBUSER"
+ "(USER_ID, USERNAME, CREATED_BY, CREATED_DATE) " + "VALUES"
+ "(101,'mkyong','system', " + "to_date('"
+ getCurrentTimeStamp() + "', 'yyyy/mm/dd hh24:mi:ss'))";

JAVA:

dbConnection.setAutoCommit(false);

statement = dbConnection.createStatement();
4 statement.addBatch(insertTableSQL1);
5 statement.addBatch(insertTableSQL2);
6 statement.addBatch(insertTableSQL3);

statement.executeBatch();

dbConnection.commit();

JDBC & PreparedStatement

The “PreparedStatement” interface is extended “Statement”, with extra feature to send a pre-compiled SQL statement with parameters. For create, insert, update or delete statement, uses “

PreparedStatement.executeUpdate(sql)

“; select query, uses “

PreparedStatement.executeQuery(sql)

“.

1、To issue a create statement, calls the

PrepareStatement.executeUpdate()

method like this :

PreparedStatement preparedStatement = dbConnection.prepareStatement(createTableSQL);
// EXECUTE CREATE SQL stetement
preparedStatement.executeUpdate();

2、To issue an insert statement, calls the

PreparedStatement.executeUpdate()

method like this :

String insertTableSQL = "INSERT INTO DBUSER"
+ "(USER_ID, USERNAME, CREATED_BY, CREATED_DATE) VALUES"
+ "(?,?,?,?)";
PreparedStatement preparedStatement = dbConnection.prepareStatement(insertTableSQL);
preparedStatement.setInt(1, 11);
preparedStatement.setString(2, "mkyong");
preparedStatement.setString(3, "system");
preparedStatement.setTimestamp(4, getCurrentTimeStamp());
// execute insert SQL stetement
preparedStatement .executeUpdate();

3、To issue a update statement, calls the

PreparedStatement.executeUpdate()

method like this :

String updateTableSQL = "UPDATE DBUSER SET USERNAME = ? WHERE USER_ID = ?";
PreparedStatement preparedStatement = dbConnection.prepareStatement(updateTableSQL);
preparedStatement.setString(1, "mkyong_new_value");
preparedStatement.setInt(2, 1001);
// execute update SQL stetement
preparedStatement .executeUpdate();

4、To issue a delete statement, calls the

PreparedStatement.executeUpdate()

method like this :

String deleteSQL = "DELETE DBUSER WHERE USER_ID = ?";
PreparedStatement preparedStatement = dbConnection.prepareStatement(deleteSQL);
preparedStatement.setInt(1, 1001);
// execute delete SQL stetement
preparedStatement.executeUpdate();

5、display the records via a ResultSet object. To issue a select query, calls the

PreparedStatement.executeQuery()

method like this

String selectSQL = "SELECT USER_ID, USERNAME FROM DBUSER WHERE USER_ID = ?";
PreparedStatement preparedStatement = dbConnection.prepareStatement(selectSQL);
preparedStatement.setInt(1, 1001);
ResultSet rs = preparedStatement.executeQuery(selectSQL );
while (rs.next()) {
String userid = rs.getString("USER_ID");
String username = rs.getString("USERNAME");
}

6、批量处理数据；Batch Update is not limit to Insert statement, it’s apply for Update and Delete statement as well.（适用于增删改）

dbConnection.setAutoCommit(false);//commit trasaction manually

String insertTableSQL = "INSERT INTO DBUSER"
+ "(USER_ID, USERNAME, CREATED_BY, CREATED_DATE) VALUES"
+ "(?,?,?,?)";
PreparedStatement = dbConnection.prepareStatement(insertTableSQL);

preparedStatement.setInt(1, 101);
preparedStatement.setString(2, "mkyong101");
preparedStatement.setString(3, "system");
preparedStatement.setTimestamp(4, getCurrentTimeStamp());
preparedStatement.addBatch();

preparedStatement.setInt(1, 102);
preparedStatement.setString(2, "mkyong102");
preparedStatement.setString(3, "system");
preparedStatement.setTimestamp(4, getCurrentTimeStamp());
preparedStatement.addBatch();
19 preparedStatement.executeBatch();

dbConnection.commit();

JDBC事务管理：

JDBC Transaction let you control how and when a transaction should commit into database.

//transaction block start

//SQL insert statement
//SQL update statement
//SQL delete statement

//transaction block end

In simple, JDBC transaction make sure SQL statements within a transaction block are all executed successful, if either one of the SQL statement within transaction block is failed, abort and rollback everything within the transaction block.

(JDBC确保了在事务块中的所有语句都执行成功，如果它们之中的一个执行失败，那么在事务中执行的所有操作都会进行回滚)

1. Without JDBC Transaction

By default, data will be committed into database when

executeUpdate()

is called.
(默认情况下，数据将会在执行executeUpdate()方法的时候，提交到数据库中)：

String insertTableSQL = "INSERT INTO DBUSER"
+ "(USER_ID, USERNAME, CREATED_BY, CREATED_DATE) VALUES"
+ "(?,?,?,?)";

String updateTableSQL = "UPDATE DBUSER SET USERNAME =? "
+ "WHERE USER_ID = ?";

preparedStatementInsert = dbConnection.prepareStatement(insertTableSQL);
preparedStatementInsert.setInt(1, 999);
preparedStatementInsert.setString(2, "mkyong101");
preparedStatementInsert.setString(3, "system");
preparedStatementInsert.setTimestamp(4, getCurrentTimeStamp());
preparedStatementInsert.executeUpdate(); //data COMMITTED into database.

preparedStatementUpdate = dbConnection.prepareStatement(updateTableSQL);
preparedStatementUpdate.setString(1, "A very very long string caused DATABASE ERROR");
preparedStatementUpdate.setInt(2, 999);

preparedStatementUpdate.executeUpdate(); //Error, value too big,  ignore this update statement,
//but user_id=999 is inserted(出错)

When this code is executed, the USER_ID = ’999′ is inserted but the username is not update.

(数据提交到数据库中去，但是后面的更新语句失败)

2. With JDBC Transaction

To put this in a transaction, you can use

1、dbConnection.setAutoCommit(false);

to start a transaction block.（开始事务）

2、dbConnection.commit();

to end a transaction block.（结束事务）

dbConnection.setAutoCommit(false); //transaction block start(手动的控制事务)

String insertTableSQL = "INSERT INTO DBUSER"
+ "(USER_ID, USERNAME, CREATED_BY, CREATED_DATE) VALUES"
+ "(?,?,?,?)";

String updateTableSQL = "UPDATE DBUSER SET USERNAME =? "
+ "WHERE USER_ID = ?";

preparedStatementInsert = dbConnection.prepareStatement(insertTableSQL);
preparedStatementInsert.setInt(1, 999);
preparedStatementInsert.setString(2, "mkyong101");
preparedStatementInsert.setString(3, "system");
preparedStatementInsert.setTimestamp(4, getCurrentTimeStamp());
preparedStatementInsert.executeUpdate(); //data IS NOT commit yet(数据当前还没有提交)

preparedStatementUpdate = dbConnection.prepareStatement(updateTableSQL);
preparedStatementUpdate.setString(1, "A very very long string caused DATABASE ERROR");
preparedStatementUpdate.setInt(2, 999);
preparedStatementUpdate.executeUpdate(); //Error, rollback, including the first insert statement.
(出现错误，所有的数据操作都进行回滚)
dbConnection.commit(); //transaction block end(手动的提交事务)

When this code is executed, update statement is hits error, and make both insert and update statements rollback together.(所有的操作都会进行回滚)