Question

这是我的数据库表，名为Cruise_Serial： enter image description here

我想获取每个cruiseID的总平均评价数，例如：

cruiseID 4013必须为：（5 + 5 + 4 + 4 + 3 + 4 + 4 + 5 + 4 + 4 + 4 + 4）/ 12 这是我为PreparedStatement编写的内容：

PreparedStatement ps = connect1.prepareStatement("SELECT CRUISE_SERIAL＿NUMBER, AVG(CRUISE_SERIAL.EVALUATION_FOOD, CRUISE_SERIAL.EVALUATION_SEHEDULE, CRUISE_SERIAL.EVALUATIONA_COMFORTABLE,CRUISE_SERIAL.EVALUATION_TIDY),AVG(CRUISE_SERIAL_NUMBER) "
          + "FROM CRUISE_SERIAL GROUP by CRUISE_SERIAL_NUMBER");

但是此行代码中显示了错误，请帮助我解决问题。谢谢！

Exception in thread "main" java.sql.SQLSyntaxErrorException: Lexical error at line 1, column 21.  Encountered: "\uff3f" (65343), after : "".
    at org.apache.derby.client.am.SQLExceptionFactory.getSQLException(Unknown Source)
    at org.apache.derby.client.am.SqlException.getSQLException(Unknown Source)
    at org.apache.derby.client.am.ClientConnection.prepareStatement(Unknown Source)
    at lab.User_Cruise.cruiseEvaluation

Answer 1

您的某些下划线不是常规的，请在此处查看第二个：

CRUISE_SERIAL＿NUMBER

错误告诉您，此 large 下划线是Unicode字符U + FF3F，即

FULLWIDTH LOW LINE

只需将其替换为常规下划线即可。

JDBC计算平均值

1 个答案: