超薄滚筒缺点:Java 中 select count时 ResultSet.getInt("mycount")异常
来源:百度文库 编辑:高考问答 时间:2024/05/21 22:34:41
public int getMsgCount(){
//得到消息数量
ResultSet rs=null;
sql="select count(*) as mycount from msg";
try{
Statement stmt = Dbconn.connectToSqlServer();
rs=stmt.executeQuery(sql);
return rs.getInt("mycount");
}catch(Exception ex){
ex.printStackTrace();
return -1;
}
}
每次返回都是-1
提示return rs.getInt("mycount");出错。
如何解决?
//得到消息数量
ResultSet rs=null;
sql="select count(*) as mycount from msg";
try{
Statement stmt = Dbconn.connectToSqlServer();
rs=stmt.executeQuery(sql);
return rs.getInt("mycount");
}catch(Exception ex){
ex.printStackTrace();
return -1;
}
}
每次返回都是-1
提示return rs.getInt("mycount");出错。
如何解决?
这是SQL语句错误,用count(*)时必须是根据某个字段的分组查询,比如:
select name,count(*) from msg group by name
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