详解Java的JDBC API的存储过程与SQL转义语法的使用

CREATE OR REPLACE PROCEDURE getEmpName 
  (EMP_ID IN NUMBER, EMP_FIRST OUT VARCHAR) AS
BEGIN
  SELECT first INTO EMP_FIRST
  FROM Employees
  WHERE ID = EMP_ID;
END;

DELIMITER $$

DROP PROCEDURE IF EXISTS `EMP`.`getEmpName` $$
CREATE PROCEDURE `EMP`.`getEmpName` 
  (IN EMP_ID INT, OUT EMP_FIRST VARCHAR(255))
BEGIN
  SELECT first INTO EMP_FIRST
  FROM Employees
  WHERE ID = EMP_ID;
END $$

DELIMITER ;

CallableStatement cstmt = null;
try {
  String SQL = "{call getEmpName (?, ?)}";
  cstmt = conn.prepareCall (SQL);
  . . .
}
catch (SQLException e) {
  . . .
}
finally {
  . . .
}

CallableStatement cstmt = null;
try {
  String SQL = "{call getEmpName (?, ?)}";
  cstmt = conn.prepareCall (SQL);
  . . .
}
catch (SQLException e) {
  . . .
}
finally {
  cstmt.close();
}

DELIMITER $$

DROP PROCEDURE IF EXISTS `EMP`.`getEmpName` $$
CREATE PROCEDURE `EMP`.`getEmpName` 
  (IN EMP_ID INT, OUT EMP_FIRST VARCHAR(255))
BEGIN
  SELECT first INTO EMP_FIRST
  FROM Employees
  WHERE ID = EMP_ID;
END $$

DELIMITER ;

//STEP 1. Import required packages
import java.sql.*;

public class JDBCExample {
  // JDBC driver name and database URL
  static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; 
  static final String DB_URL = "jdbc:mysql://localhost/EMP";

  // Database credentials
  static final String USER = "username";
  static final String PASS = "password";
  
  public static void main(String[] args) {
  Connection conn = null;
  CallableStatement stmt = null;
  try{
   //STEP 2: Register JDBC driver
   Class.forName("com.mysql.jdbc.Driver");

   //STEP 3: Open a connection
   System.out.println("Connecting to database...");
   conn = DriverManager.getConnection(DB_URL,USER,PASS);

   //STEP 4: Execute a query
   System.out.println("Creating statement...");
   String sql = "{call getEmpName (?, ?)}";
   stmt = conn.prepareCall(sql);
   
   //Bind IN parameter first, then bind OUT parameter
   int empID = 102;
   stmt.setInt(1, empID); // This would set ID as 102
   // Because second parameter is OUT so register it
   stmt.registerOutParameter(2, java.sql.Types.VARCHAR);
   
   //Use execute method to run stored procedure.
   System.out.println("Executing stored procedure..." );
   stmt.execute();

   //Retrieve employee name with getXXX method
   String empName = stmt.getString(2);
   System.out.println("Emp Name with ID:" + 
        empID + " is " + empName);
   stmt.close();
   conn.close();
  }catch(SQLException se){
   //Handle errors for JDBC
   se.printStackTrace();
  }catch(Exception e){
   //Handle errors for Class.forName
   e.printStackTrace();
  }finally{
   //finally block used to close resources
   try{
     if(stmt!=null)
      stmt.close();
   }catch(SQLException se2){
   }// nothing we can do
   try{
     if(conn!=null)
      conn.close();
   }catch(SQLException se){
     se.printStackTrace();
   }//end finally try
  }//end try
  System.out.println("Goodbye!");
}//end main
}//end JDBCExample

C:>javac JDBCExample.java

C:>java JDBCExample

Connecting to database...
Creating statement...
Executing stored procedure...
Emp Name with ID:102 is Zaid
Goodbye!

{keyword 'parameters'}

{d 'yyyy-mm-dd'}

//Create a Statement object
stmt = conn.createStatement();
//Insert data ==> ID, First Name, Last Name, DOB
String sql="INSERT INTO STUDENTS VALUES" +
       "(100,'Zara','Ali', {d '2001-12-16'})";

stmt.executeUpdate(sql);

{t 'hh:mm:ss'}

{ts 'yyyy-mm-dd hh:mm:ss'}

String sql = "SELECT symbol FROM MathSymbols
       WHERE symbol LIKE '\%' {escape ''}";
stmt.execute(sql);

{fn length('Hello World')}

{call my_procedure(?)};

{? = call my_procedure(?)};

{oj outer-join}

String sql = "SELECT Employees 
       FROM {oj ThisTable RIGHT
       OUTER JOIN ThatTable on id = '100'}";
stmt.execute(sql);