我可以从DatabaseMetaData查询更改Resultset中的获取模式吗？
我正在使用DatabaseMetaData实例检查数据库。我获得了DB中表的所有信息，并且我迭代了所有Resultset而没有任何问题。
在迭代结束时，我想返回到ResultSet的开头，所以我调用beforeFirst（）方法，然后调用next（）来获取ResultSet的第一个元素。这是我的代码：
connect(request.getParameter("source"));
DatabaseMetaData patrol = link.getMetaData();
answer = patrol.getTables(null, null, null, null);
while (answer.next()) {
String nomTable = answer.getString("TABLE_NAME");
System.out.println(nomTable)
}
answer.beforeFirst();
answer.next();
String table = answer.getString("TABLE_NAME");
answer.close();
java.sql.SQLException: Result set type is TYPE_FORWARD_ONLY
at sun.jdbc.odbc.JdbcOdbcResultSet.beforeFirst(Unknown Source)
at InspectDB.doPost(InspectDB.java:59)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:747)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:840)
at com.sun.web.core.ServletWrapper.handleRequest(ServletWrapper.java:155
)
at com.sun.web.core.InvokerServlet.service(InvokerServlet.java:168)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:840)
at com.sun.web.core.ServletWrapper.handleRequest(ServletWrapper.java:155
)
at com.sun.web.core.Context.handleRequest(Context.java:414)
at com.sun.web.server.ConnectionHandler.run(ConnectionHandler.java:139)
answer.setFetchDirection(ResultSet.FETCH_REVERSE);
answer.beforeFirst();
answer.next();
java.lang.NullPointerException
at sun.jdbc.odbc.JdbcOdbcResultSet.setFetchDirection(Unknown Source)
at InspectDB.doPost(InspectDB.java:58)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:747)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:840)
at com.sun.web.core.ServletWrapper.handleRequest(ServletWrapper.java:155)
at com.sun.web.core.InvokerServlet.service(InvokerServlet.java:168)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:840)
at com.sun.web.core.ServletWrapper.handleRequest(ServletWrapper.java:155)
at com.sun.web.core.Context.handleRequest(Context.java:414)
at com.sun.web.server.ConnectionHandler.run(ConnectionHandler.java:139)
没有找到相关结果
已邀请:
1 个回复
嗓瑰
void setFetchDirection(int direction) throws SQLException Gives a hint as to the direction in which the rows in this ResultSet object will be processed. The initial value is determined by the Statement object that produced this ResultSet object. The fetch direction may be changed at any time. Parameters: direction - an int specifying the suggested fetch direction; one of ResultSet.FETCH_FORWARD, ResultSet.FETCH_REVERSE, or ResultSet.FETCH_UNKNOWN Throws: SQLException - if a database access error occurs; this method is called on a closed result set or the result set type is TYPE_FORWARD_ONLY and the fetch direction is not FETCH_FORWARD Since: 1.2 See Also: Statement.setFetchDirection(int), getFetchDirection()