java中出现错误“ORA-00942：表或视图不存在”

Question

我正在尝试学习连接到oracle数据库当我以这种方式登录 sqlplus 时：sqlplus sys/Oracle_1@orcl as sysdba;我运行这段代码：connect hr/hr@orclpdbselect count(*) from employees;我得到这个输出： COUNT(*)----------       107但是当我尝试在 java 代码中访问该表时，出现此错误：ORA-00942: table or view does not exist这是我的java代码：class OracleCon{  public static void main(String args[]){  try{  Class.forName("oracle.jdbc.driver.OracleDriver");  Connection con=DriverManager.getConnection(          "jdbc:oracle:thin:hr/hr@localhost:1521/orclpdb","sys as sysdba","Oracle_1"); Statement stmt=con.createStatement();  ResultSet rs=stmt.executeQuery("select count(*) from employees");  while(rs.next())  System.out.println(rs.getInt(1)+"  "+rs.getString(2)+"  "+rs.getString(3));  con.close();  }catch(Exception e){ System.out.println(e);}  }  }  我应该怎么做才能解决这个问题？

Answer 1

您正在尝试使用 java 代码中的用户连接它sys，但表employee存在于hr架构中。

您可以更改：

//Change this line from

Connection con=DriverManager.getConnection(  

        "jdbc:oracle:thin:hr/hr@localhost:1521/orclpdb","sys as sysdba","Oracle_1"); 

// to

Connection con=DriverManager.getConnection(  

        "jdbc:oracle:thin:hr/hr@localhost:1521/orclpdb","hr","hr"); 

或者

您可以更改从表中获取数据的方式employee（使用其架构查询表）

//Change this line from

ResultSet rs=stmt.executeQuery("select count(*) from employees"); 

//to

ResultSet rs=stmt.executeQuery("select count(*) from hr.employees"); 

干杯！！

Answer 2

请尝试一下这段代码。它必须工作

public static void conn() throws ClassNotFoundException, SQLException{  

    Connection con=DriverManager.getConnection(  

            "jdbc:oracle:thin:@localhost:1521:orclpdb", "HR", "HR"); 

    Statement stmt=con.createStatement();  

    ResultSet rs=stmt.executeQuery("select count(*) from dual");  

    while(rs.next())  

        System.out.println(rs.getInt(1));  

    con.close();

}