这不是一个很简单的手术吗?但是,我看到既没有size()也没有length()方法。


当前回答

String sql = "select count(*) from message";
ps =  cn.prepareStatement(sql);

rs = ps.executeQuery();
int rowCount = 0;
while(rs.next()) {
    rowCount = Integer.parseInt(rs.getString("count(*)"));
    System.out.println(Integer.parseInt(rs.getString("count(*)")));
}
System.out.println("Count : " + rowCount);

其他回答

获取ResultSet大小的方法,不需要使用数组列表等

int size =0;  
if (rs != null)   
{  
rs.beforeFirst();  
 rs.last();  
size = rs.getRow();
}

现在你会得到大小,如果你想打印ResultSet,在打印之前使用以下一行代码,

rs.beforeFirst();  
theStatement=theConnection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);

ResultSet theResult=theStatement.executeQuery(query); 

//Get the size of the data returned
theResult.last();     
int size = theResult.getRow() * theResult.getMetaData().getColumnCount();       
theResult.beforeFirst();

当使用rs.last()时,我得到了一个异常

if(rs.last()){
    rowCount = rs.getRow(); 
    rs.beforeFirst();
}

:

java.sql.SQLException: Invalid operation for forward only resultset

因为默认情况下它是ResultSet。TYPE_FORWARD_ONLY,这意味着只能使用rs.next()

解决方案是:

stmt=conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
    ResultSet.CONCUR_READ_ONLY); 
String sql = "select count(*) from message";
ps =  cn.prepareStatement(sql);

rs = ps.executeQuery();
int rowCount = 0;
while(rs.next()) {
    rowCount = Integer.parseInt(rs.getString("count(*)"));
    System.out.println(Integer.parseInt(rs.getString("count(*)")));
}
System.out.println("Count : " + rowCount);

今天,我用了这个逻辑,为什么我不知道得到RS的计数。

int chkSize = 0;
if (rs.next()) {
    do {  ..... blah blah
        enter code here for each rs.
        chkSize++;
    } while (rs.next());
} else {
    enter code here for rs size = 0 
}
// good luck to u.