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錯誤的程式碼如下:

 stmt=conn.createStatement();

 rs=stmt.executeQuery("select * from t1");

 rst=stmt.executeQuery("select * from t2"

 rs.last();

    //由於執行了rst=stmt.executeQuery(sql_a);rs就會被關閉掉！所以程式執行到此會提示ResultSet已經關閉.錯誤資訊為:java.sql.SQLException: Operation not allowed after ResultSet closed

rst.last();

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stmt=conn.createStatement();

rs=stmt.executeQuery("select * from t1");

rs.last();//對rs的操作應馬上操作,操作完後再從資料庫得到rst,再對rst操作

rst=stmt.executeQuery("select * from t2");

rst.last();

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多個stmt對應各自的rs.

stmt=conn.createStatement();

stmt2=conn.createStatement();

rs=stmt.executeQuery("select * from t1");

rst=stmt2.executeQuery("select * from t2");

rs.last();

rst.last();