Java sql ResultSet 没有数据

Question

我想从java中的sql数据库中提取一个数据。我尝试使用 resultSet，但是当我想将第一行减入 int 变量时，它说结果集没有内容。

这是我的代码

try {
            statement = connexion.createStatement();
            statementArtist = connexion.createStatement();
            String artist = "Mac Miller";
            ResultSet resultat = statement.executeQuery("USE albums SELECT Album.numero_artist FROM Album INNER JOIN Artist ON Album.num_artist = Artiste.num_artist where name like '"+artist+"'");    
            int result = resultat.getInt(1); // Here is the problem
            String query = "USE albums INSERT INTO dbo.Album(Album.num_artist, title, price, genre, date, home, image) VALUES("
                    + result
                    + ", '"
                    + title
                    + "', "
                    + price
                    + ", '"
                    + genre
                    + "', '"
                    + date
                    + "', '"
                    + home
                    + "', '"
                    + image
                    + "')";
            statement.executeUpdate(query);

Answer 1

您应该在结果集上调用next()方法以"移动"迭代器：

...
ResultSet resultat = statement.executeQuery("USE albums SELECT Album.numero_artist FROM Album INNER JOIN Artist ON Album.num_artist = Artiste.num_artist where name like '"+artist+"'");    
resultat.next();           
int result = resultat.getInt(1); // Here is the problem
...

如果安全性和更好的性能对您的应用程序很重要，则还应考虑使用预准备语句。

Answer 2

需要使用 next（），也应该测试结果，即

ResultSet resultat = statement.executeQuery("USE albums SELECT Album.numero_artist FROM Album INNER JOIN Artist ON Album.num_artist = Artiste.num_artist where name like '"+artist+"'");    
if (resultat.next()) {
    int result = resultat.getInt(1); // Here is the problem

此外，诸如"+艺术家+"之类的容易出错，例如，如果艺术家包含引号"大多数数据库都会出现 Sql 错误。使用 Sql 参数提供