SQL连接类
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>
/// 初始化 /// </summary>
public DataControl()
{
}
/// <summary>
/// 无参数，测试数据库连接是否设置合理。 /// </summary>
/// <returns>是否连接成功</returns>
public static bool checkconn()
{
try
{
SqlConnection conn = new SqlConnection(connectionString);
conn.Open();
return true;
}
&
相关文档：
Subquery: (single-row subqueries and multi-rows subqueries).
select select_list
from table
where expr operator (select select_list from table);
single-row subqueries operator: =, >, >=, <, <=, <>
e.g.:
1. select department_id, min(salary) from employees group by department_id ......
GRANT
Name
GRANT -- 定义访问权限
Synopsis GRANT { { SELECT | INSERT | UPDATE | DELETE | RULE | REFERENCES | TRIGGER }
[,...] | ALL [ PRIVILEGES ] }
ON [ TABLE ] tablename [, ...]
TO { username | GROUP groupname | PUBLIC } [, ...] [ WI ......
Confirming granted privileges
Data Dictionary View Description
ROLE_SYS_PRIVS System privileges granted to roles
ROLE_TAB_PRIVS & ......
PairWise subquery:
e.g.:
select * from wf_docsort where (ndocsortid,nmoduleinfoid) in (select ndocsortid, nmoduleinfoid from wf_docsort where instr(cname,'文')>0)
the above sql is the same function as:
select * from wf_docsort where ndocsortid = (select ndocsortid from wf_docsort where ......
