如何在 SQL 中使用 join 删除记录？

Question

我的程序有问题我正在尝试使用 Java 连接从表中删除一条记录，这是我的代码：

try{
            String sql ="DELETE f FROM facture f INNER JOIN client c ON f.idClient=c.id WHERE c.nom= ? ORDER BY idFact DESC LIMIT 1";
            PreparedStatement pr = conn.prepareStatement(sql);
            pr.setString(1,nom);
            pr.executeUpdate();
            System.out.println("supprimer");
        }catch (SQLException e){
            e.printStackTrace();
        }

这是错误：

java.sql.SQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'ORDER BY idFact DESC LIMIT 1' at line 1.

Answer 1

在 MySQL/MariaDB 中，您有一个选择：

• 您可以使用ORDER BY和LIMIT ，而FROM只能引用一张表。
• 您可以拥有一个引用多个表的FROM 。

解决方案？ 改写查询：

DELETE FROM facture f 
    WHERE EXISTS (SELECT 1
                  FROM client c 
                  WHERE f.idClient = c.id AND c.nom = ? 
                 )
    ORDER BY f.idFact DESC
    LIMIT 1;

或者您可以使用子查询来获取要删除的行：

DELETE f
    FROM facture f JOIN
         (SELECT f.idFact
          FROM facture f JOIN
               client c
               ON f.idClient = c.id AND c.nom = ?
          ORDER BY f.idFact DESC
          LIMIT 1
         ) ff
         ON ff.idFact = f.idFact