JDBC的使用-----Statement
时间：2021-07-01 10:21:17
帮助过：6人阅读
1.加载数据库驱动类
1)在工程下新建lib文件夹，将 ojdbc6.jar（jar包在：E:\oracle\product\11.2.0\dbhome_1\jdbc\lib）拷贝至该目录下
2)右键ojdbc6.jar文件，build path --> add too build path
3)将驱动类加载到内存中
Class.forName("oracle.jdbc.driver.OracleDriver");
2.获取数据库连接对象
Connection conn = DriverManager.getConnection(url,user,password);
3.写sql
String sql = "xxxxxx";
4.创建PreparedStatement对象
PreparedStatement ps = conn.prepareStatement(sql);
5.执行查询返回ResultSet结果集对象
ResultSet rs = ps.executeQuery();
6.遍历结果集，获取查询结果
while(rs.next){
rs.getXxx()
}
7.释放资源
rs.close()
ps.close()
conn.close()
JDBC连接字符串MySQL：
String Driver="com.mysql.jdbc.Driver"; //驱动程序
String URL="jdbc:mysql://localhost:3306/db_name"; //连接的URL,db_name为数据库名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver);
Connection con=DriverManager.getConnection(URL,Username,Password);
Oracle:
String Driver="oracle.jdbc.driver.OracleDriver"; //连接数据库的方法
String URL="jdbc:oracle:thin:@localhost:1521:orcl"; //orcl为数据库的SID
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver) ; //加载数据库驱动
Connection con=DriverManager.getConnection(URL,Username,Password); //常用数据库链接方式
DB2：
String Driver="com.ibm.dbjdbc.app.DBDriver"; //连接具有DB2客户端的Provider实例
//String Driver="com.ibm.dbjdbc.net.DBDriver"; //连接不具有DB2客户端的Provider实例
String URL="jdbc:db2://localhost:5000/db_name"; //db_name为数据库名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver) ;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class TestStatement {
public static void main(String[] args) {
try {
//1.加载数据库驱动文件
Class.forName(
"oracle.jdbc.driver.OracleDriver");
//2。获取数据库连接对象
String url =
"jdbc:oracle:thin:@127.0.0.1:1521:orcl";
String user =
"SCOTT";
String password =
"tiger";
Connection conn =
DriverManager.getConnection(url, user, password);
//3.通过connection对象获取一个Statement对象，用于sql语句发送到数据库
testExecuteQuery(conn.createStatement());
System.out.println(
"--------------------");
testExecuteUpdate(conn.createStatement());
System.out.println(
"---------------------");
testExcute(conn.createStatement());
//5.遍历结果集
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(
"请检查连接驱动类是否正确");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void testExecuteUpdate(Statement stmt) throws SQLException {
String sql =
"insert into emp(empno,ename,sal) values(434,‘mm‘,5000)";
int result =
stmt.executeUpdate(sql);
System.out.println(result);
}
public static void testExecuteQuery(Statement stmt) throws SQLException {
//4.获取结果集对象
//executeQuery 只能用在select关键字的查询中
String sql =
"select e.ename ee,e.empno from emp e";
ResultSet rs =
stmt.executeQuery(sql);
while(rs.next()) {
System.out.println(rs.getString(
"ee")+
"\t"+rs.getInt(
"empno"));
}
}
public static void testExcute(Statement stmt) throws SQLException {
//execute方法可以执行任意的sql语句
String sql =
"select * from emp";
boolean flag =
stmt.execute(sql);
ResultSet rs =
stmt.getResultSet();
System.out.println(flag);
while(rs.next()) {
System.out.println(rs.getString(
"empno"));
}
}
}
import java.sql.Connection;import java.sql.DatabaseMetaData;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;
public class TestJDBCgetTable {public static void main(String[] args) {Connection conn = null;ResultSet columns = null;try {//加载数据库驱动文件Class.forName("oracle.jdbc.driver.OracleDriver");conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:orcl", "SCOTT", "tiger");//获取数据库的元信息DatabaseMetaData metaData = conn.getMetaData();//查看数据库中有哪些表/*ResultSet rs = metaData.getTables(conn.getCatalog(), "SCOTT", null, new String[]{"TABLE"});while(rs.next()) {System.out.println(rs.getString(3));}*/columns = metaData.getColumns(conn.getCatalog(), "SCOTT", "EMP", null);while(columns.next()) {System.out.println(columns.getString(4));}} catch (ClassNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally {try {if(columns!=null) {columns.close();}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}try {if(conn!=null) {conn.close();}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}
JDBC的使用-----Statement
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