[英]Storing rows from a MySQL table into an array in Java
我正在尝试将表中的行存储到数组中。 我可以获得第一个结果并将其存储,但似乎无法存储任何其他数据。
这是我写的代码
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);
}
}
知道我哪里出错了吗?
将while
-condition更改为hasNext()
并在循环内使用next()
将数据库光标向前移动。
尝试使用以下方法:
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";
一次验证列名称。 有时ALIAS
问题,我不确定为什么。
从结果集中获取元数据:
ResultSetMetaData metaData = resultSet.getMetaData();
int size = metaData.getColumnCount();
for (int i = 0; i < size; i ++)
System.out.println(metaData.getColumnName(i);
同样为了提高性能,请列出列名,而不要在SELECT
查询中使用*
。 另外,您可以看看com.sun.rowset.CachedRowSetImpl.
它的用法如下:
CachedRowSetImpl crs = new CachedRowSetImpl();
crs.populate(resultSet);
我认为它也实现了CachedRowSet
,但是我不确定。
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