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using System;
using System.Collections;
using System.Collections.Specialized;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace DAL
{
    public class DataControl
    {
        public static string connectionString = "server=" + SystemSet.getServerSet_ServerIP() + ";uid=" + SystemSet.getServerSet_ServerUser() + ";pwd=" + SystemSet.getServerSet_ServerPass() + ";database=" + SystemSet.getServerSet_ServerDataBase() + "";
        /// <summary>
        /// ³õʼ»¯        /// </summary>
        public DataControl()
        {
        }
        /// <summary>
        /// ÎÞ²ÎÊý£¬²âÊÔÊý¾Ý¿âÁ¬½ÓÊÇ·ñÉèÖúÏÀí¡£        /// </summary>
        /// <returns>ÊÇ·ñÁ¬½Ó³É¹¦</returns>
        public static bool checkconn()
        {
            try
            {
                SqlConnection conn = new SqlConnection(connectionString);
                conn.Open();
                return true;
            }
 &


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Subquery: (single-row subqueries and multi-rows subqueries).
select select_list
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single-row subqueries operator: =, >, >=, <, <=, <>
e.g.:
1. select department_id, min(salary) from employees group by department_id ......

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1. My test: (create and grant the sysdba to a new user by SQL*Plus)
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REVOKE SYSDBA from FJTEST;
CONNECT FJTEST1/JEANJEANFANG AS SYSDBA;
2. Using ORAPWD in windows:
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