我的數據庫是MySQL的從XAMPP 運行我有3個colums id,nazwa,kwota
我不斷收到一個錯誤:Java的SQL語句未知列ID
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'main' in 'field list'
我認爲問題是出在
String sql = ("SELECT id, nazwa, kwota");
ResultSet rs = stmt.executeQuery(sql);
,但我正在尋找差不多2個小時,似乎沒有找到答案... Im絕望,謝謝
import java.sql.*;
import javax.sql.*;
public class JdbcDriver{
public static void main(String args[]) {
Connection conn = null;
Statement stmt = null;
String username = "wojtek";
String password = "3445222";
String url = "jdbc:mysql://localhost:3306/javatest";
try{
//STEP 2: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");
//STEP 3: Open a connection
System.out.println("Connecting to a selected database...");
conn = DriverManager.getConnection(url, username, password);
System.out.println("Connected database successfully...");
//STEP 4: Execute a query
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql = ("SELECT id, nazwa, kwota");
ResultSet rs = stmt.executeQuery(sql);
//STEP 5: Extract data from result set
while(rs.next()){
//Retrieve by column name
int id = rs.getInt("id");
String nazwa = rs.getString("nazwa");
int kwota = rs.getInt("kwota");
//Display values
System.out.print("ID: " + id);
System.out.print(", Nazwa: " + nazwa);
System.out.print(", kwota: " + kwota);
}
rs.close();
}catch(SQLException se){
//Handle errors for JDBC
se.printStackTrace();
}catch(Exception e){
//Handle errors for Class.forName
e.printStackTrace();
}finally{
//finally block used to close resources
try{
if(stmt!=null)
conn.close();
}catch(SQLException se){
}// do nothing
try{
if(conn!=null)
conn.close();
}catch(SQLException se){
se.printStackTrace();
}//end finally try
}//end try
System.out.println("Goodbye!");
}//end main
}//end JDBCExample
您的聲明似乎缺少'FROM'和一個TABLE。 –
添加表名,學習如何編寫sql語句 – Nishank