新手入门-怎样返回表的总数？？

Question

String sql = "select count(*) from tablename";
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver"); 
String url="jdbc:microsoft:sqlserver://host:port;DatabaseName=dbname"; 
String userName = "userName";
String password = "password";
Connection conn = DriverManager.getConnection(url, userName,
password);
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql);
int count = 0;
if(rs.next())
count = rs.getInt(1);
rs.close();
stmt.close();
conn.close();
return count;

Answer 1

try catch or throws 自己加吧

Answer 2

ResultSet rs = stmt.executeQuery("select count(*) as cou from entity1");
rs.first();
System.out.println(rs.getString("cou"));

Answer 3

import java.sql.*;
public class TestCon{
public static void main(String[] args){
Connection con = null;
String DRIVERNAME = "com.mysql.jdbc.Driver";
String URL = "jdbc:mysql://localhost:3306/photo?useUnicode=true&characterEncoding=utf-8";
String user = "root" ;
String password = "root" ;
String fullURL = URL+"&user="+user+"&password="+password ;
try{
Class.forName(DRIVERNAME);
System.out.println("Driver OK!");
}catch(Exception e){
System.out.println("Driver fail!");
e.printStackTrace();
}
try{
con = DriverManager.getConnection(fullURL);
System.out.println("Connection OK!");
}catch(Exception e){
System.out.println("Connection fail!");
e.printStackTrace();
}
try{
Statement stmt = con.createStatement();
stmt.executeUpdate("insert into entity1 values ('aa',1,2,3,4,5)");
ResultSet rs = stmt.executeQuery("select count(*) as cou from entity1");
rs.first();
System.out.println(rs.getString("cou"));
con.close();
}catch(Exception e){

e.printStackTrace();
}finally{

}

}
};

Answer 4

public int count(){
Statement stmt=null;
ResultSet rs=null;
Connection conn =null;
int count = 0;
                  String sql = "select count(*) from tablename";
try{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver"); 
}catch(ClassNotFoundException e){
System.out.print(e);
}
try{
String url="jdbc:microsoft:sqlserver://host:port;DatabaseName=dbname"; 
String userName = "userName";
String password = "password";
conn = DriverManager.getConnection(url, userName,password);
    stmt = conn.createStatement();
    rs = stmt.executeQuery(sql);
if(rs.next())
count = rs.getInt(1);
rs.close();
stmt.close();
conn.close();
}catch(SQLException e){
System.out.print(e);
}
return count;
}