Question

这就是我得到的

com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that
corresponds to your MySQl server version for the right syntax to use near 'order by idconsumo' at line 1

java.lang.IllegalArgumentException: Cannot set a null TableModel

码

 sSQL = "select c.idconsumo,c.idreserva,c.idproducto,p.nombre,c.cantidad,c.precio_venta "
                + ",c.estado from  consumo c inner join producto p on c.idproducto=p.idproducto"
                + " where c.idreserva = " + buscar +" order by idconsumo";

但仍将其保存在数据库中。如果我退出应用程序并再次打开它然后记录已添加

Answer 1

首先，如Jon建议的那样，使用参数化的SQL。

您需要对SQL进行一些更改，如下所示：

"select c.idconsumo, c.idreserva, c.idproducto, p.nombre, c.cantidad, c.precio_venta, c.estado from  consumo c inner join producto p on c.idproducto=p.idproducto where c.idreserva = " + buscar +" order by c.idconsumo";

确保buscar是变量而c.idreserva是非int列，然后在c.idreserva = '" + buscar +"'和order by c.idconsumo

之间添加单引号

使用预备陈述：

String sql = "select c.idconsumo, c.idreserva, c.idproducto, p.nombre, c.cantidad, c.precio_venta, c.estado from  consumo c inner join producto p on c.idproducto=p.idproducto where c.idreserva = ? order by c.idconsumo";
PreparedStatement prepStmt = conn.prepareStatement(sql);
//if buscar is string type
prepStmt.setString(1, buscar);
ResultSet rs = prepStmt.executeQuery();

Answer 2

查询语法错误。请检查：

   String sql = " select c.idconsumo,c.idreserva,c.idproducto,p.nombre,"
               +" c.cantidad,c.precio_venta, c.estado "
               +" from  consumo c inner join producto p on "
               +" c.idproducto=p.idproducto "
               +" where c.idreserva ='" + buscar +"' order by c.idconsumo ";

PreparedStatement可以更准确地使用。

PreparedStatement是一种特殊的Statement对象，具有一些有用的功能。请记住，您需要一个Statement才能执行查询或更新。您可以使用PreparedStatement而不是Statement，并从PreparedStatement的功能中受益。

PreparedStatement的主要功能是：

易于将参数插入SQL语句中。易于重复使用带有新参数的PreparedStatement。可能会提高性能执行的陈述。实现更轻松的批量更新。

       String sql = " select c.idconsumo,c.idreserva,c.idproducto,p.nombre,"
                   +" c.cantidad,c.precio_venta, c.estado "
                   +" from  consumo c inner join producto p on "
                   +" c.idproducto=p.idproducto "
                   +" where c.idreserva = ? order by c.idconsumo ";

PreparedStatement preStmt = conn.prepareStatement(sql);
preStmt.setInt(1, buscar);
ResultSet rs = preStmt.executeQuery();

java sql语句版本错误

2 个答案: