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Initial JDBC programming

2022-07-02 12:09:00 【The dishes are not right】

Catalog

🥬 Specific operation

1、 open IDEA, Create a new project first

2、 Introduce dependencies ,JDBC Programming requires mysql Driver package .( The driver package is to mysq| Self api To convert into jdbc Style ). Download the driver package , Choose with yourself mysql The version corresponds to the version of the driver package .

3、 Import the driver package into the project

1） First create a directory in the new project just created

2） Download the jar Copy the file to the directory just created

3） Right click the directory just now , choice Add as library…

4、 Write code

🥬JDBC The basic programming process

1、 establish DataSource object , This object describes where the database server is .

Describe where the server is

2、 Let the code connect to the database server

  Connection connection=dataSource.getConnection();

3、 Operate on the database

Take inserting data ：

 // The key is to construct a  SQL  sentence 
  String sql="insert into student values(1,“ Zhang San ”)";
 //  Here is just a  String  Type of  sql  Not yet ,  You need to put this  String  Pack it as a  " Statement object "
  PreparedStatement statement=connection.prepareStatement(sql);

4、 perform SQL

// SQL  If it's  insert, update, delete,  All use  executeUpdate  Method .
// SQL  If it's  select,  Then use  executeQuery  Method .
// The return value indicates the operation ,  Affected several lines .
  int ret= statement.executeUpdate();
  System.out.println(ret);

5、SQL After execution , Release resources

// Create before release 
 statement.close();
 connection.close();

The specific code is as follows ：

public class TestJDBC {
    public static void main(String[] args) throws SQLException {
        Scanner scanner=new Scanner(System.in);

        //1、 create data source 
        DataSource dataSource=new MysqlDataSource();
        // Set the location of the database 
        ((MysqlDataSource) dataSource).setURL("jdbc:mysql://127.0.0.1:3306/testdemo?characterEncoding=utf8&useSSL=false");
        // Set the user name to log in to the database 
        ((MysqlDataSource) dataSource).setUser("root");
        // Set the password to log in to the database 
        ((MysqlDataSource) dataSource).setPassword("123456");

        //2、 Let the code establish a connection with the database server 
        Connection connection=dataSource.getConnection();
        //2.1  Input data from the console 
        System.out.println(" Please enter the student number ：");
        int id=scanner.nextInt();
        System.out.println(" Please enter a name ");
        String name=scanner.next();

        //3、 Operating the database , Take inserting data 
        // The key is to construct a  SQL  sentence 
        String sql="insert into student values(?,?)";
        //？ It's equivalent to occupying a position , The values of these two fields are still uncertain , The following is used PrepareStatement Medium setxxx Replace with a series of methods 
        //  Here is just a  String  Type of  sql  Not yet ,  You need to put this  String  Pack it as a  " Statement object "
        PreparedStatement statement=connection.prepareStatement(sql);
        // Carry out replacement operations 
        statement.setInt(1,id);
        statement.setString(2,name);
        System.out.println("statement:"+statement);

        // 4、 perform  SQL
        // SQL  If it's  insert, update, delete,  All use  executeUpdate  Method .
        // SQL  If it's  select,  Then use  executeQuery  Method .
        //  The return value indicates the operation ,  It's affecting   A few lines .  It's equivalent to typing... In the console  sql  after ,  The numbers you get 
        int ret= statement.executeUpdate();
        System.out.println(ret);

        //5、 here SQL completion of enforcement , Need to release resources 
        // Create before release 
        statement.close();
        connection.close();
    }
}