SQL 未命名参数语法

Posted 2023-05-09

【中文标题】SQL 未命名参数语法

【英文标题】：SQL unnamed parameter syntax

【发布时间】：2020-11-23 08:04:24

【问题描述】：

我检查了两次，为什么会这样？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；检查手册 对应于您的 MariaDB 服务器版本以获取正确的语法 to 在'附近使用？ , ? , ? , ? ,?,? )' 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);

【参考方案1】：

您可能编辑了问题，尝试了一些方法。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);
    

【讨论】：

@EmanuelMosby 注意&& sentencia.getLong(1) > 0L 我稍后在不需要的代码中添加。

【参考方案2】：

在retorno = sentencia.executeUpdate(sql);尝试删除参数sql