Create a jdbc connection

This paper introduces how to establish a jdbc connection for database query.

Create a java project and import the jar package.

Using mysql database, the author needs mysql database driver jar package and jdbc connection jar package to establish jdbc connection.

  

The process of establishing a jdbc connection is as follows:

1. Load database driver

2. Create and obtain database connection

3. Create JDBC statement object

4. Set sql statement

5. Set parameters in sql statement

6. Execute sql through statement and get the result

7. Parse the sql execution results

8. Release resources

 1 package com.xyfer;
 2 
 3 import java.sql.Connection;
 4 import java.sql.DriverManager;
 5 import java.sql.PreparedStatement;
 6 import java.sql.ResultSet;
 7 import java.sql.SQLException;
 8 
 9 public class JdbcTest {
10 
11     public static void main(String[] args) {
12         
13         Connection connection = null;
14         PreparedStatement preparedStatement = null;
15         ResultSet resultSet = null;
16         
17         try {
18             //Load database driver
19             Class.forName("com.mysql.jdbc.Driver");
20             
21             //Get database link through driver management class
22             connection =  DriverManager.getConnection("jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8", "root", "root");
23             //Definition sql Sentence ?Represents a placeholder
24             String sql = "select * from user where username = ?";
25             //Get preprocessing statement
26             preparedStatement = connection.prepareStatement(sql);
27             //Set the parameter, the first parameter is sql The sequence number of the parameter in the statement (starting from 1), and the second parameter is the set parameter value
28             preparedStatement.setString(1, "Small black");
29             //Issue to database sql Execute query to find result set
30             resultSet =  preparedStatement.executeQuery();
31             //Traverse query result set
32             while(resultSet.next()){
33                 System.out.println(resultSet.getString("id")+"  "+resultSet.getString("username"));
34             }
35         } catch (Exception e) {
36             e.printStackTrace();
37         }finally{
38             //Release resources
39             if(resultSet!=null){
40                 try {
41                     resultSet.close();
42                 } catch (SQLException e) {
43                     // TODO Auto-generated catch block
44                     e.printStackTrace();
45                 }
46             }
47             if(preparedStatement!=null){
48                 try {
49                     preparedStatement.close();
50                 } catch (SQLException e) {
51                     // TODO Auto-generated catch block
52                     e.printStackTrace();
53                 }
54             }
55             if(connection!=null){
56                 try {
57                     connection.close();
58                 } catch (SQLException e) {
59                     // TODO Auto-generated catch block
60                     e.printStackTrace();
61                 }
62             }
63         }
64     }
65 
66 }

Tags: Java SQL Database JDBC

Posted on Sat, 07 Dec 2019 02:08:08 -0500 by Barb54