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Record the first JDBC
2022-07-06 10:19:00 【Artificial intelligence cockroach】
Record the first JDBC
JDBC What are the
bring Java Connect to database ; Can pass java Drive different databases uniformly .
To configure JDBC
Guide pack
1. 1. 1. MySQL I use it 5.7.19, then maven Failed to import package , There is no corresponding one on the official website jar package , Finally, I saw a post saying ,5.7 Version of MySQL Direct use mysql-connector-java-5.1.34.jar The above jar Just a bag ;
2. 2. 2. Then import jar After package , Connect MySQL You need to set the time zone , Set to GMT Just ok 了 ;
3. 3. 3. After entering the user's password Click on test connection
4. 4. 4. Click on Schemas
I was then Schemas It's always empty , I found a lot of information and didn't solve it , The last restart idea Just fine ;
5. 5. 5. After successful connection , The database information can be displayed .
Insert a row
package com.tl.study01;
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
/** * @author tl * Insert a row id value ( key ) Can't repeat */
public class TestJdbc02 {
public static void main(String[] args) throws Exception {
// Configuration information
//useUnicode=true&characterEncoding=utf-8 Solve the Chinese garbled code
String url="jdbc:mysql://localhost:3306/jdbc_study?" +
"useUnicode=true&characterEncoding=utf-8";
String username = "root";
String password = "123";
//1. The load driver
Class.forName("com.mysql.jdbc.Driver");
//2. Connect to database ,connection On behalf of the database
Connection connection = DriverManager.getConnection(url, username, password);
//3. To write SQL
String sql = "insert into users(id, name, password, email, birthday) values (?,?,?,?,?);";
//4. precompile ( Security )
PreparedStatement preparedStatement = connection.prepareStatement(sql);
// Give the first placeholder ? The value of is assigned to 4;
preparedStatement.setInt(1,4);
// Give the second placeholder ? The value of is assigned to root;
preparedStatement.setString(2,"root");
// Give the third placeholder ? The value of is assigned to 123;
preparedStatement.setString(3,"123");
// Give the fourth placeholder ? The value of is assigned to [email protected];
preparedStatement.setString(4,"[email protected]");
// Give the fifth placeholder ? The value of is assigned to new Date(new java.util.Date().getTime());
preparedStatement.setDate(5,new Date(new java.util.Date().getTime()));
//5. perform SQL
int i = preparedStatement.executeUpdate();
if (i>0){
System.out.println(" Insert the success @");
}
//6. Close the connection , Release resources ( Be sure to do ) Turn it on and off
preparedStatement.close();
connection.close();
}
}
Delete a line
package com.tl.study01;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
/** * @author tl * Delete a line */
public class TestJdbc03 {
public static void main(String[] args) throws Exception {
// Configuration information
//useUnicode=true&characterEncoding=utf-8 Solve the Chinese garbled code
String url="jdbc:mysql://localhost:3306/jdbc_study?" +
"useUnicode=true&characterEncoding=utf-8";
String username = "root";
String password = "123";
//1. The load driver
Class.forName("com.mysql.jdbc.Driver");
//2. Connect to database ,connection On behalf of the database
Connection connection = DriverManager.getConnection(url, username, password);
//3. To write SQL
String sql = "delete from users where id =2";
//4. precompile ( Security )
PreparedStatement preparedStatement = connection.prepareStatement(sql);
int i = preparedStatement.executeUpdate(sql);
if (i>0){
System.out.println(" Delete successful @");
}
//6. Close the connection , Release resources ( Be sure to do ) Turn it on and off
preparedStatement.close();
connection.close();
}
}
Query table information
package com.tl.study01;
import java.sql.*;
/** * @author tl * Look up the table */
public class TestJdbc01 {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
//"useUnicode=true&characterEncoding=utf-8" Solve the Chinese garbled code
String url="jdbc:mysql://localhost:3306/jdbc_study?" +
"useUnicode=true&characterEncoding=utf-8";
String username = "root";
String password ="123";
// Drive by reflection loading
Class.forName("com.mysql.jdbc.Driver");
// Connect to database ,connection On behalf of the database
Connection connection = DriverManager.getConnection(url, username, password);
// Send to the database SQL The object of Statement:CRUD
Statement statement = connection.createStatement();// unsafe
// To write SQL Execute the query SQL, Return to one ResultSet: Result set
String sql ="select * from users";
ResultSet res = statement.executeQuery(sql);
while (res.next()){
System.out.println("id="+res.getObject("id"));
System.out.println("name="+res.getObject("name"));
System.out.println("password="+res.getObject("password"));
System.out.println("email="+res.getObject("email"));
System.out.println("birthday="+res.getObject("birthday"));
}
//6. Close the connection , Release resources ( Be sure to do ) Turn it on and off
res.close();
statement.close();
connection.close();
}
}
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