学习Unity3D之SQL代码查询和用VS向数据库插入、删除、更新、查询信息。

欢迎来到unity学习、unity培训、unity企业培训教育专区，这里有很多U3D资源、U3D培训视频、U3D教程、U3D常见问题、U3D项目源码，我们致力于打造业内unity3d培训、学习第一品牌。一、SQL查询代码。
1、查询全部的行和列。
       select*from student
2、查询部分行。
       select name,password from student where id<>3  //查询student表中id不是3的name与password信息。
3、命名列名查询。
       select id as 学号,name as 姓名,password as 密码 from student
4、去掉重复字段查询记录。
      select distinct name from student   //去掉student中name重复的行。
5、合并查询。
       select*from student union select*from student2
6、查询非空行。
       select name from student where name is not null
7、使用常量列。   
       select 姓名=name,'密码' password from student
8、限制固定行数。
       select top 2 id,name,password from student where name='王五'
9、返回百分比行数。
       select top 50 percent id,name,password from student where name='王五'
10、排序。
       select id,name,password from student
       where name='王五'
       order by password asc
11、按多列排序。
       select id as 学号,name as 姓名,password as 密码
       from student
       where password>100
       order by id,name
二、在VS中往数据库插入（删除、更新）数据。
       class Program
       {
           public int Insert()
           {
               SqlConnection s = new SqlConnection("server=.;database=Class2;Trusted_Connection=SSpI");
               //string sql = "insert into student(name,password) values('王五','789')";       //插入数据。
               //string sql = "delete from student where password=234";       //删除数据。
               string sql = "update Student set password=234 where name='王五'";       //更新数据
               SqlCommand comm = new SqlCommand(sql, s);
               s.Open();
               int count = comm.ExecuteNonQuery();
               return count;
           }
           static void Main(string[] args)
           {
               Console.WriteLine(new Program().Insert());
               Console.ReadKey();
           }
       }
三、用VS查询表中数据。
       class Program
       {
           public List<Person> GetNum()
           {
               List<Person> p = new List<Person>();
               SqlConnection s = new SqlConnection("server=.;database=Class2;Trusted_Connection=SSpI");
               s.Open();
               SqlCommand cmd = new SqlCommand("select*from student", s);
               SqlDataReader reader = cmd.ExecuteReader();
               while (reader.Read())
               {
                   Person ss = new Person();
                   ss.SetId((int)reader.GetValue(0));
                   ss.SetName((string)reader.GetValue(1));
                   ss.SetPassword((int)reader.GetValue(2));
                   p.Add(ss);
               }
               reader.Close();
               s.Close();
               return p;
           }
           static void Main(string[] args)
           {
               List<Person> p = new Program().GetNum();
               foreach (Person ss in p)
               {
                   Console.WriteLine(ss.GetId() + "   " + ss.GetName() + "   " + ss.GetPassword());
               }
               Console.ReadKey();
           }
       }