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java - SQL 未命名参数语法

问题描述

我检查了两次为什么会继续发生这种情况？我有正确数量的未命名参数，列名是正确的。

*

您的 SQL 语法有错误；查看与您的 MariaDB 服务器版本相对应的手册，以了解在 '? 附近使用的正确语法。, ? , ? , ? ,?,? )'在第 1 行

public void adiciona(Libro libro) {
    try {
    String sql = "insert into libro (isbn, titulo, precio, stock, cod_categoria, cod_editorial) values ( ? , ? , ? , ? ,?,? )";
    String sqlQuery = "select count(*) from libro where isbn = " + libro.getIsbn();
    sentencia = connection.createStatement();
    resultSet = sentencia.executeQuery(sqlQuery);
    resultSet.next();
    if (resultSet.getInt(1) == 0) {
    try (PreparedStatement preparedStatement = connection.prepareStatement(sql)) {
        
      
        preparedStatement.setInt(1, libro.getIsbn());
        preparedStatement.setString(2, libro.getTitulo());
        preparedStatement.setDouble(3, libro.getPrecio());
        preparedStatement.setInt(4, libro.getStock());
        preparedStatement.setInt(5, libro.getCod_categoria());
        preparedStatement.setInt(6, libro.getCod_editorial());
        
        retorno = sentencia.executeUpdate(sql);
        
        preparedStatement.execute();
    } catch (SQLIntegrityConstraintViolationException e) {
        System.out.printf("error duplicado: %s\n",e);
    } 
    catch (SQLException e) {
        throw new RuntimeException(e);
    }
    }else if(retorno> 0) {System.out.println("added");
        
    }else { System.out.println("no added.");}
    

}catch (SQLException e) {
    throw new RuntimeException(e);
}
}

标签： javamysqlsqlmariadb

解决方案

您可能编辑了问题，尝试了一些事情。一个干净的版本是：

public void adiciona(Libro libro) {
    
    // Not needed:
    String sqlQuery = "select count(*) from libro where isbn = ?";
    try (PreparedStatement sentencia = connection.createStatement(sqlQuery)) {
        sentencia.setInt(libro.getIsbn());
        try (ResultSet resultSet = sentencia.executeQuery()) {
            if (resultSet.next() && sentencia.getLong(1) > 0L) {
                return;
            }
        }
    } catch (SQLException e) {
        throw new RuntimeException(e);
    }

   String sql = "insert into libro (isbn, titulo, precio, stock, cod_categoria, cod_editorial) "
        + "values (?, ?, ?, ?, ?, ?)";
    try (PreparedStatement preparedStatement = connection.prepareStatement(sql)) {
        preparedStatement.setInt(1, libro.getIsbn());
        preparedStatement.setString(2, libro.getTitulo());
        preparedStatement.setDouble(3, libro.getPrecio());
        preparedStatement.setInt(4, libro.getStock());
        preparedStatement.setInt(5, libro.getCod_categoria());
        preparedStatement.setInt(6, libro.getCod_editorial());
        
        int retorno = preparedStatement.executeUpdate();
        if (retorno > 0) {
            System.out.println("added")
        } else {
            System.out.println("not added.");
        }
    } catch (SQLIntegrityConstraintViolationException e) {
        System.out.printf("error duplicado: %s\n", e);
        throw new RuntimeException(e);
    } catch (SQLException e2) {
        throw new RuntimeException(e2);
    }
}

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