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Exemples d'instructions JDBC - Insérer, supprimer, mettre à jour, sélectionner un enregistrement

Cet article vous montrera comment utiliser java.sql.Statement pour exécuter des commandes d'insertion, de mise à jour, de suppression et de sélection SQL DML avec des exemples.

1. Utilisez java.sql.Statement.execute(String sql) pour exécuter la commande d'insertion, de mise à jour et de suppression.

/* This method can be used to execute insert, update, delete dml command. */
public void executeSql(String ip, int port, String dbName, String userName, String password, String sql)
{
	/* Declare the connection and statement object. */
	Connection conn = null;
	Statement stmt = null;
	try
	{
		/* Get connection object. */
		conn = this.getMySqlConnection(ip, port, dbName, userName, password);
		
		/* Get statement object. */
		stmt = conn.createStatement();
		
		/* The method can execute insert, update and delete dml command. */
		stmt.execute(sql);
		
		System.out.println("Execute sql successfuly, " + sql);
	}catch(Exception ex)
	{
		ex.printStackTrace();
	}finally
	{
		this.closeDBResource(stmt, conn);
	}
}
     

/* Close statement and connection after use, this can avoid resource waste. */
public void closeDBResource(Statement stmt, Connection conn)
{
	try
	{
		if(stmt!=null)
		{
			stmt.close();
			stmt = null;
		}
		
		if(conn!=null)
		{
			conn.close();
			conn = null;
		}
	}catch(Exception ex)
	{
		ex.printStackTrace();
	}
}

2. Insérer et renvoyer les clés générées automatiquement.

Pour la commande d'insertion, utilisez java.sql.Statement.execute(String sql, int autoGeneratedKeys) pour insérer et renvoyer la valeur de la clé d'auto-incrémentation, il s'agit de la valeur de l'identifiant dans cet exemple.

/* Execute insert command and return the auto generated record id. */
public int executeInsertSql(String ip, int port, String dbName, String userName, String password, String sql)
{
	int ret = -1;
	/* Declare the connection and statement object. */
	Connection conn = null;
	Statement stmt = null;
	try
	{
		/* Get connection object. */
		conn = this.getMySqlConnection(ip, port, dbName, userName, password);
		
		/* Get statement object. */
		stmt = conn.createStatement();
		
		/* The method can execute insert dml command and return auto generated key values. */
		stmt.execute(sql, Statement.RETURN_GENERATED_KEYS);
		
		ResultSet rs = stmt.getGeneratedKeys();
			
		if(rs.next())
		{
			/* Please note the index start from 1 not 0. */
			ret = rs.getInt(1);
		}			
		
		System.out.println("Execute sql successfuly, " + sql);
	}catch(Exception ex)
	{
		ex.printStackTrace();
	}finally
	{
		this.closeDBResource(stmt, conn);
		return ret;
	}
	
}

3. Exécutez la commande select SQL.

/* This method can be used to execute select dml command. */
public List executeSelectSql(String ip, int port, String dbName, String userName, String password, String selectSql)
{
	List ret = new ArrayList();
	/* Declare the connection and statement object. */
	Connection conn = null;
	Statement stmt = null;
	try
	{
		/* Get connection object. */
		conn = this.getMySqlConnection(ip, port, dbName, userName, password);
		
		/* Get statement object. */
		stmt = conn.createStatement();
		
		/* The method can execute select dml command. */
		ResultSet rs = stmt.executeQuery(selectSql);
		
		if(rs!=null)
		{
			while(rs.next())
			{
				int teacherId = rs.getInt("id");
				
				String teacherName = rs.getString("name");
				
				String teahcerEmail = rs.getString("email");
			
				TeacherDTO teacherDto = new TeacherDTO();
				
				teacherDto.setId(teacherId);
				
				teacherDto.setName(teacherName);
				
				teacherDto.setEmail(teahcerEmail);
				
				ret.add(teacherDto);
				
				System.out.println("id = " + teacherDto.getId());
				System.out.println("name = " + teacherDto.getName());
				System.out.println("email = " + teacherDto.getEmail());
				System.out.println("**************************************");
			}
		}
		
		System.out.println("Execute sql successfuly, " + selectSql);
	}catch(Exception ex)
	{
		ex.printStackTrace();
	}finally
	{
		this.closeDBResource(stmt, conn);
		return ret;
	}

}

4. EnseignantDTO.java.

Cette classe est utilisée pour enregistrer un enregistrement de données dans la table des enseignants.

package com.dev2qa.java.jdbc;

/* This class represent one record in database teacher table. */
public class TeacherDTO {
	
	private int id;
	
	private String name;
	
	private String email;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}
}

5. Exemple de code complet.

  1. Cet exemple utilisera un test de base de données MySQL et table professeur , le professeur la table a trois colonnes, elles sont id , nom, et e-mail . Vous pouvez consulter JDBC Create Table Example Use Statement pour en savoir plus.
  2. Vous pouvez créer le tableau enseignant dans phpMyAdmin. Vous devez ajouter un nom de colonne est id , le type est int, et vérifie le A_I case à cocher pour l'incrémenter automatiquement.

5.1 Exemple d'étapes de code :

  1. Insérez un enregistrement (bonjour, [email protected]).
  2. Insérez un autre enregistrement (hello1, [email protected]) et renvoyez l'ID d'enregistrement généré automatiquement.
  3. La mise à jour du nom en jerry utilise le deuxième identifiant d'enregistrement.
  4. Interroger tous les enregistrements dans le enseignant tableau.
  5. Supprimer l'enregistrement dont l'adresse e-mail est [email protected]
  6. Répertorier tous les enregistrements dans le enseignant table à nouveau.
public static void main(String[] args) {
		
	/* Below are db connection required data. */
	String ip = "localhost";
	int port = 3306;
	String dbName = "test";
	String userName = "root";
	String password = "";
	
	/* Create an instance. */
	JDBCStatementExample jdbcStatementExample = new JDBCStatementExample();
	
	/* Insert one record. */
	String insertSql = "insert into teacher(name, email) values('hello','[email protected]')";
	/* Execute the insert command. */
	jdbcStatementExample.executeSql(ip, port, dbName, userName, password, insertSql);
	
	/* Insert another record. */
	insertSql = "insert into teacher(name, email) values('hello1','[email protected]')";
	/* Execute the insert command. */
	int autoGenId = jdbcStatementExample.executeInsertSql(ip, port, dbName, userName, password, insertSql);
	
	/* update record. */
	String updateSql = "update teacher set name = 'jerry' where id = " + autoGenId;
	/* Execute the update command. */
	jdbcStatementExample.executeSql(ip, port, dbName, userName, password, updateSql);
	
	/* select records. */
	String selectSql = "select * from teacher";
	jdbcStatementExample.executeSelectSql(ip, port, dbName, userName, password, selectSql);
	
	String deleteSql = "delete from teacher where email = '[email protected]'";
	jdbcStatementExample.executeSql(ip, port, dbName, userName, password, deleteSql);
	
	/* select records after delete. */
	selectSql = "select * from teacher";
	jdbcStatementExample.executeSelectSql(ip, port, dbName, userName, password, selectSql);
}


/* This method return java.sql.Connection object from MySQL server. */
public Connection getMySqlConnection(String ip, int port, String dbName, String userName, String password)
{
	/* Declare and initialize a sql Connection variable. */
	Connection ret = null;
	
	try
	{
	
		/* Register for mysql jdbc driver class. */
		Class.forName("com.mysql.jdbc.Driver");
		
		/* Create mysql connection url. */
		String mysqlConnUrl = "jdbc:mysql://" + ip + ":" + port + "/" + dbName;
		
		/* Get the mysql Connection object. */
		ret = DriverManager.getConnection(mysqlConnUrl, userName , password);
	}catch(Exception ex)
	{
		ex.printStackTrace();
	}finally
	{
		return ret;
	}
}

Sortie

<terminated> JDBCStatementExamp|e [Java Application] C:\Java\jrel.B.O_131\bin\javaw.exe [Aug 28, 2017, 7:59:53 PM]
Execute sql successfuly, insert into teacher(name, email) values('hello','[email protected]')
Execute sql successfuly, insert into teacher(name, email) values('hello1','[email protected]')
Execute sql successfuly, update teacher set name = 'jerry' where id = 22
id = 21
name = hello
email = [email protected]
**************************************
id = 22
name = jerry
email = [email protected]
**************************************
Execute sql successfuly, select * from teacher
Execute sql successfuly, delete from teacher where email = '[email protected]'
id = 21
name = hello
email = [email protected]
**************************************
Execute sql successfuly, select * from teacher