將MySQL表中的行存儲到Java中的數組中

Question

我正在嘗試將表中的行存儲到數組中。 我可以獲得第一個結果並將其存儲，但似乎無法存儲任何其他數據。

這是我寫的代碼

try 
    {
        test = "select * from Arsenal order by 'MatchNumber' ASC";                
        rs = st.executeQuery(test); 

        while (rs.next()) 
        {
            //This retrieves each row of Arsenal table and adds it to an array in the Team Results class.

            matchno = rs.getString("MatchNumber");                    
            hometeam = rs.getString("HomeTeam");                      
            awayteam = rs.getString("AwayTeam");                         
            homegoals = rs.getString("HomeGoals");                   
            awaygoals = rs.getString("AwayGoals");                   
            result = rs.getString("Result");                             


            teams = (matchno + "," + hometeam + "," + awayteam + "," + homegoals + "," + awaygoals + "," + result);     // Takes all the variables containging a single customers information and puts it into a string, seperated by commas.
            TeamResults.add(matchno,hometeam,awayteam,homegoals,awaygoals,result);
        }
    }

知道我哪里出錯了嗎？

Answer 1

將while -condition更改為hasNext()並在循環內使用next()將數據庫光標向前移動。

Answer 2

嘗試使用以下方法：

 public void SelectData(String sqlcounter ,String sql){

        try {
         RsCounter=stmt.executeQuery(sqlcounter);
            System.out.println(sqlcounter);
            while(RsCounter.next()){

                countrow=RsCounter.getInt("COUNTR");
                System.out.println(countrow+"\n");
                             }
            System.out.println(sql);
         RsSelecting = stmt.executeQuery(sql);
         data=new String[countrow][RsSelecting.getMetaData().getColumnCount()];

         header= new String[RsSelecting.getMetaData().getColumnCount()];

     i=0;
     while(RsSelecting.next()){
      for(j=0;j<RsSelecting.getMetaData().getColumnCount();j++){

              data[i][j]=(RsSelecting.getString(j+1));
              header[j]=RsSelecting.getMetaData().getColumnName(j+1);
              System.out.print(data[i][j]+"\n");

     }    


      i++;

     }
      i=j=0;
        } catch (SQLException ex) {
                       ex.printStackTrace();

            Logger.getLogger(Connect.class.getName()).log(Level.SEVERE, null, ex);
        }
   }

哪里

sqlcounter ="select COUNT(*) as COUNTR from Arsenal order by 'MatchNumber' ASC";

和

sql ="select * from Arsenal order by 'MatchNumber' ASC";

Answer 3

一次驗證列名稱。 有時ALIAS問題，我不確定為什么。

從結果集中獲取元數據：

ResultSetMetaData metaData = resultSet.getMetaData();
int size = metaData.getColumnCount();

for (int i = 0; i < size; i ++)
    System.out.println(metaData.getColumnName(i);

同樣為了提高性能，請列出列名，而不要在SELECT查詢中使用* 。 另外，您可以看看com.sun.rowset.CachedRowSetImpl. 它的用法如下：

CachedRowSetImpl crs = new CachedRowSetImpl();
crs.populate(resultSet);

我認為它也實現了CachedRowSet ，但是我不確定。