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JDBC初步

2024-07-28 18:37:34   221人阅读

JDBC

 1 import java.sql.*; 2  3 public class TestJDBC { 4     public static void main(String[] args) { 5         ResultSet rs = null; 6         Statement stmt = null; 7         Connection conn = null; 8         try { 9             // Class是java.lang的包， 给名子把类的实例new出来 可能找不到类 抛异常ClassNotFoundException10             // 自动向drivermanager注册11             Class.forName("com.mysql.jdbc.Driver");12             String url = "jdbc:mysql://127.0.0.1:3307/world";13             conn = DriverManager.getConnection(url, "hill", "hill");14             stmt = conn.createStatement();15             rs = stmt.executeQuery("select * from city");16             while (rs.next()) {17                 System.out.println(rs.getString("Name"));18             }19         } catch (ClassNotFoundException e) {20             e.printStackTrace();21         } catch (SQLException e) {22             e.printStackTrace();23         } finally {24             try {25                 if (rs != null) {26                     rs.close();27                 }28                 if (stmt != null) {29                     stmt.close();30                 }31                 if (conn != null) {32                     conn.close();33                 }34             } catch (SQLException e) {35                 e.printStackTrace();36             }37         }38 39     }40 41 }

DML1

import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class TestDML {	public static void main(String[] args) {		Statement stmt = null;		Connection conn = null;		try {			// Class是java.lang的包， 给名子把类的实例new出来 可能找不到类 抛异常ClassNotFoundException			// 自动向drivermanager注册			Class.forName("com.mysql.jdbc.Driver");			String url = "jdbc:mysql://127.0.0.1:3307/samp_db";			conn = DriverManager.getConnection(url, "hill", "hill");			stmt = conn.createStatement();			String sql = "insert into tab_user values (02,‘hehe‘)";			stmt.executeUpdate(sql);		} catch (ClassNotFoundException e) {			e.printStackTrace();		} catch (SQLException e) {			e.printStackTrace();		} finally {			try {				if (stmt != null) {					stmt.close();				}				if (conn != null) {					conn.close();				}			} catch (SQLException e) {				e.printStackTrace();			}		}	}}

DML2

import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class TestDML2 {	public static void main(String[] args) {		if (args.length != 2) {			System.out.println("Parameter Error!");			System.exit(-1);		}		int num = 0;		try {			num = Integer.parseInt(args[0]);		} catch (NumberFormatException e) {			System.out.println("Parameter Error! NumberFormatException!");			System.exit(-1);		}		String name = args[1];		Statement stmt = null;		Connection conn = null;		try {			// Class是java.lang的包， 给名子把类的实例new出来 可能找不到类 抛异常ClassNotFoundException			// 自动向drivermanager注册			Class.forName("com.mysql.jdbc.Driver");			String url = "jdbc:mysql://127.0.0.1:3307/samp_db";			conn = DriverManager.getConnection(url, "hill", "hill");			stmt = conn.createStatement();			String sql = "insert into tab_user values " + "(" + num + ",‘"					+ name + "‘)";			System.out.println(sql);			stmt.executeUpdate(sql);		} catch (ClassNotFoundException e) {			e.printStackTrace();		} catch (SQLException e) {			e.printStackTrace();		} finally {			try {				if (stmt != null) {					stmt.close();				}				if (conn != null) {					conn.close();				}			} catch (SQLException e) {				e.printStackTrace();			}		}	}}

PreparedStatement

import java.sql.*;public class TestPrepStmt {	public static void main(String[] args) {		if (args.length != 2) {			System.out.println("Parameter Error!");			System.exit(-1);		}		int num = 0;		try {			num = Integer.parseInt(args[0]);		} catch (NumberFormatException e) {			System.out.println("Parameter Error! NumberFormatException!");			System.exit(-1);		}		String name = args[1];		PreparedStatement pstmt = null;		Connection conn = null;		try {			// Class是java.lang的包， 给名子把类的实例new出来 可能找不到类 抛异常ClassNotFoundException			// 自动向drivermanager注册			Class.forName("com.mysql.jdbc.Driver");			String url = "jdbc:mysql://127.0.0.1:3307/samp_db";			conn = DriverManager.getConnection(url, "hill", "hill");			pstmt = conn.prepareStatement("inset into tab_user values(?,?,?)");			pstmt.setInt(1,num);			pstmt.setString(2,name);			pstmt.executeUpdate();		} catch (ClassNotFoundException e) {			e.printStackTrace();		} catch (SQLException e) {			e.printStackTrace();		} finally {			try {				if (pstmt != null) {					pstmt.close();				}				if (conn != null) {					conn.close();				}			} catch (SQLException e) {				e.printStackTrace();			}		}	}}

批处理

Transaction

可滚动的结果集

JDBC初步


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