tatic final string delall_tb_message = "delete from tb_message";
public static final string reply_tb_message = "insert into tb_message (mes_content,mes_sender,mes_sendtime,to_whom) values(?,?,?,?,?)";
public static final string add_tb_link = "insert into tb_link (link_name,link_add) values (?,?)";
public static final string del_tb_link = "delete from tb_link where link_id=?";
public static final string query_tb_link = "select link_id,link_name,link_add from tb_link";
// public static final string part_article = "select article_id,title,content,phtime,number from tb_article order by article_id desc";
public static final string part_article = "select article_id,title,content,phtime,number,typename from tb_article left join tb_articletype on (tb_article.type_id=tb_articletype.type_id) order by article_id desc";
public static final string show_link = "select * from tb_link ";
public static final string show_note = "select * from tb_note order by note_id desc";
public static final string add_tb_video = "insert into tb_video (video_name,video_time) values(?,?)";
public static final string add_tb_test = "insert into tb_test (test_name,test_time,user_name) values(?,?,?)";
public static final string query_tb_video = "select video_name,video_time from tb_video order by video_id desc";
public static final string query_tb_test = "select test_name,test_time,user_name from tb_test order by test_id desc";
public static final string del_tb_video = "delete from tb_video where video_name=?";
}
第7章 开发中遇到的难点和对策
a. 数据库的连接问题
问题:数据库的连接:在开发过程中经常出现查找不到数据库,出现这样的错误一般是数据库的连接出现问题。
数据库加载驱动有问题。一开始用的是
class.forname("com.microsoft.jdbc.sqlserver.sqlserverdriver").newinstance();
stirng url = "jdbc:microsoft:sqlserver://localhost:1433;databasename=mywork";
要求有三个库文件:msbase.jar,mssqlserver.jar,msutil.jar,该文件需要放在服务器的/web-inf/lib文件夹下面.
解决方法:经检查发现1433端口没有打开,于是就换成下面的odbc-jdbc桥驱动:
class.forname("sun.jdbc.odbc.jdbcodbcdriver");
string url="jdbc:odbc:mydb";
connection con=drivermanager.getconnection("jdbc:odbc:mywork");
换成这个驱动就可以连上数据库了。
b. 从数据库中查询信息时会出错
问题:把查询的结果集rs放在arraylist的对象list中,可是在jsp页面中调用的时候却没有值。
解决方法:经检查发现,向maf中set相应属性时,顺序必须跟sql查询语句中的查询的顺序一样才可以。
while(rs.next()){
maf = new messageactionform();
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