rs=stat.executeQuery("SELECT * FROM users where users.username="+uname);
出现列名无效。整个程序为:
import java.sql.*;
public class DB
{
public static void main(String []args){
String url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=blog";
Connection con=null;
Statement stat=null;
ResultSet rs=null;
String uname="uname";
try{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
System.out.println("驱动程序已装载");
System.out.println("即将连接数据库");
}catch(Exception e){
System.out.println("无法加载驱动程序:"+e.getMessage());
return;
}
try{
con=DriverManager.getConnection(url,"sa","sa");
stat=con.createStatement();
rs=stat.executeQuery("SELECT * FROM users where users.username="+uname);
System.out.println("查询结果为:");
while(rs.next()){
System.out.println(rs.getString(1)+rs.getString(2)
+rs.getString(3)+rs.getString(4)+rs.getString(5)+rs.getString(6));
}
rs.close();
stat.close();
con.close();
}catch(SQLException ex){
while(ex!=null){
ex.printStackTrace();
ex=ex.getNextException();
}
}
}
}
在Eclipse中出现如下结果:驱动程序已装载
即将连接数据库
java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]列名 'uname' 无效。
at com.microsoft.jdbc.base.BaseExceptions.createException(Unknown Source)
at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processErrorToken(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReplyToken(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSExecuteRequest.processReplyToken(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReply(Unknown Source)
at com.microsoft.jdbc.sqlserver.SQLServerImplStatement.getNextResultType(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.commonTransitionToState(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.postImplExecute(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.commonExecute(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.executeQueryInternal(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.executeQuery(Unknown Source)
at DB.main(DB.java:21)
出现列名无效。整个程序为:
import java.sql.*;
public class DB
{
public static void main(String []args){
String url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=blog";
Connection con=null;
Statement stat=null;
ResultSet rs=null;
String uname="uname";
try{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
System.out.println("驱动程序已装载");
System.out.println("即将连接数据库");
}catch(Exception e){
System.out.println("无法加载驱动程序:"+e.getMessage());
return;
}
try{
con=DriverManager.getConnection(url,"sa","sa");
stat=con.createStatement();
rs=stat.executeQuery("SELECT * FROM users where users.username="+uname);
System.out.println("查询结果为:");
while(rs.next()){
System.out.println(rs.getString(1)+rs.getString(2)
+rs.getString(3)+rs.getString(4)+rs.getString(5)+rs.getString(6));
}
rs.close();
stat.close();
con.close();
}catch(SQLException ex){
while(ex!=null){
ex.printStackTrace();
ex=ex.getNextException();
}
}
}
}
在Eclipse中出现如下结果:驱动程序已装载
即将连接数据库
java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]列名 'uname' 无效。
at com.microsoft.jdbc.base.BaseExceptions.createException(Unknown Source)
at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processErrorToken(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReplyToken(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSExecuteRequest.processReplyToken(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReply(Unknown Source)
at com.microsoft.jdbc.sqlserver.SQLServerImplStatement.getNextResultType(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.commonTransitionToState(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.postImplExecute(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.commonExecute(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.executeQueryInternal(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.executeQuery(Unknown Source)
at DB.main(DB.java:21)
不加引号的话dbms会把uname的值当作一个列名的
改为:
rs=stat.executeQuery("SELECT * FROM users u where u.username='"+uname+"'");就好了