Java 程式設計 -- 資料庫 - 陳鍾誠的網站

範例：個人資料查詢 (簡易版)

import java.util.*;
import java.sql.*;
 
class Sql2 {
  public static void main(String[] args) throws Exception {
    Sql2 sql = new Sql2();
    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
    Connection con = DriverManager.getConnection("jdbc:odbc:Driver="+
      "{Microsoft Access Driver (*.mdb)};DBQ=person;DriverID=22;READONLY=false}");
    Statement stmt = con.createStatement();
    ResultSet rs = stmt.executeQuery("SELECT * FROM person");
    while (rs.next()) {
      String name = rs.getString("name");
      String tel  = rs.getString("tel");
      String email = rs.getString("email");
      String address = rs.getString("address");
      System.out.println(name);
      System.out.println("  電話 : "+tel);
      System.out.println("  E-mail : "+email);
      System.out.println("  地址 : "+address);
    }
    con.close();
  }
}

範例：個人資料查詢 (完整版)

import java.util.*;
import java.sql.*;
 
class Sql1 {
  Connection con = null;
  Statement  stmt = null;
  String     driver = "sun.jdbc.odbc.JdbcOdbcDriver";
  String     dbHead = "jdbc:odbc:";
 
  public static void main(String[] args) throws Exception {
    Sql1 sql = new Sql1();
    sql.openDB("person");
    ResultSet rs = sql.stmt.executeQuery("SELECT * FROM person");
    while (rs.next()) {
      String name = rs.getString("name");
      String tel  = rs.getString("tel");
      String email = rs.getString("email");
      String address = rs.getString("address");
      System.out.println(name);
      System.out.println("  電話 : "+tel);
      System.out.println("  E-mail : "+email);
      System.out.println("  地址 : "+address);
    }
    sql.closeDB();
  }
 
  void openDB(String dbName) throws Exception {
    Class.forName(driver);
    con = DriverManager.getConnection(dbHead+dbName);
    stmt = con.createStatement();
  }
 
  void closeDB() throws Exception {
    con.close();
  }
}

範例：取得資料庫的 Metadata

import java.util.*;
import java.sql.*;
 
class SqlMeta {
  public static void main(String[] args) throws Exception {
    SqlMeta sql = new SqlMeta();
    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
    Connection con = DriverManager.getConnection("jdbc:odbc:Driver="+
      "{Microsoft Access Driver (*.mdb)};DBQ=person;DriverID=22;READONLY=false}");
    Statement stmt = con.createStatement();
    DatabaseMetaData meta = con.getMetaData();
    ResultSet mrs = meta.getCatalogs();
    System.out.println("===========meta==========\n"+meta);
    System.out.println("===========metaRs==========\n"+mrs);
    while (mrs.next()) {
        String field = mrs.getString("TABLE_CAT");
        System.out.println(field);
    }
    showDatabaseMetaData(meta);
  }
 
  public static void showDatabaseMetaData(DatabaseMetaData dbmd) throws SQLException {
/*    displayResult(dbmd.getProcedures(null,null,null));    */
    displayResult(dbmd.getTables(null,null,null,null));
/*    displayResult(dbmd.getColumns(null,null,null,null));
    displayResult(dbmd.getColumnPrivileges(null,null,null,null));
    displayResult(dbmd.getPrimaryKeys(null,null,null));
    displayResult(dbmd.getTypeInfo());    */
  }
 
  public static void displayResult(ResultSet rs) throws SQLException
  {
    ResultSetMetaData rsmd = rs.getMetaData();
    int count=0;
 
    // Print the result column names
    int cols = rsmd.getColumnCount();
    for(int i=1;i<=cols;i++)
      System.out.print(rsmd.getColumnLabel(i)+(i<cols?"\t":"\n"));
 
    // now the results
    while(rs.next()) {
      count++;
      for(int i=1;i<=cols;i++) {
    Object o = rs.getObject(i);
    if(rs.wasNull())
      System.out.print("{null}"+(i<cols?"\t":"\n"));
    else
      System.out.print(o.toString()+(i<cols?"\t":"\n"));
      }
    }
 
    System.out.println("Result returned "+count+" rows.");
 
    // finally close the result set
    rs.close();
  }
}