Question

jsp页面中String sql = "select * from users"; ResultSet rs = connection.executeQuery(sql);报错

package p7;
import java.sql.*;

public class JDBConnection {
private final String dbDriver="com.microsoft.jdbc.sqlserver.SQLServerDriver";
private final String url="jdbc:microsoft:sqlserver://localhost:1433;DataBaseName=sy_users";
private final String userName="sa";
private final String password="";
private Connection con=null;
public JDBConnection(){
try {
Class.forName(dbDriver).newInstance();
}catch(Exception ex){
System.out.println("数据库加载失败");
}
}
public boolean creatConnection(){
try{
con=DriverManager.getConnection(url,userName,password);
con.setAutoCommit(true);
}catch(SQLException e){
}
return true;
}
public boolean executeUpdate(String sql){
if(con==null){
creatConnection();
}
try{
Statement stmt=con.createStatement();
int iCount=stmt.executeUpdate(sql);
System.out.println("操作成功，所影响的记录数为"+String.valueOf(iCount));
return true;
}catch(SQLException e){
return false;
}
}
public ResultSet executeQuery(String sql){
ResultSet rs;
try{
if(con==null){
creatConnection();
}
Statement stmt=con.createStatement();
rs=stmt.executeQuery(sql);
return rs;
}catch(Exception e){
return null;
}
}
public void closeConnection(){
if(con==null){
try{
con.close();
}catch(SQLException e){
}
}
}

}

JDBConnection connection = new JDBConnection();
String sql = "select * from users";
ResultSet rs = connection.executeQuery(sql);
说ResultSet cannot be resolved to a type

Answer 1

ResultSet cannot be resolved to a type 一般的意思是不能解析的类型 你检查下 你是否引入了ResultSet的包 确切一点的说 你是否引入的是sql.ResultSet 我曾经引包的时候引成别的目录下面的包了 也报了上面的错误

追问

导入了，也不行。这个办法试过了

Answer 2

dbDriver= "com.microsoft.sqlserver.jdbc.SQLServerDriver";
url="jdbc:sqlserver://localhost:1433;DataBaseName=sy_users";
rs应该为空。

追问

也试过了

Answer 3

你把ResultSet定义放到private Connection con=null;下面
也定义为null