求一段简单代码

Question

1.定义一个变量，将一个SQL语句赋值给它（判断有无此表格）。
2.执行变量，判断返回值定义为布尔值。
3.若TRUE，输出A。若FALSE，则输出B。菜鸟，谢谢了。

Answer 1

using (System.Data.SqlClient.SqlConnection conn = new System.Data.SqlClient.SqlConnection())
        {
            conn.ConnectionString = "server=.;uid=sa;pwd=**;database=数据库";
            conn.Open();
            using (System.Data.SqlClient.SqlCommand command = conn.CreateCommand())
            {
                command.CommandText = "select isnull(object_id('表格'),-1)";
                object obj= command.ExecuteScalar();
                bool b = Convert.ToInt32(obj.ToString()) >= 0;
                Console.WriteLine(b?"a":"b");
            }
            conn.Close();
        }

Answer 2

bool count;
            string connString="Data Source=.;Initial Catalog=MySchool;Integrated Security=True";
            SqlConnection conn = new SqlConnection(connString);
            string sql = "select * from student";           
            SqlCommand command=new SqlCommand(sql,conn);
            conn.Open();
            count = Convert.ToBoolean(command.ExecuteScalar());
            if (count==true)
            {
               
                MessageBox.Show("A");
            }
            else
            {
                MessageBox.Show("B");
            }

Answer 3

扩展
using (System.Data.SqlClient.SqlConnection conn = new System.Data.SqlClient.SqlConnection()) 
        { 
            conn.ConnectionString = "server=.;uid=sa;pwd=**（可以用Integrated Security=true);database=数据库名"; 
            conn.Open(); 
            using (System.Data.SqlClient.SqlCommand command = conn.CreateCommand()) 
            { 
                command.CommandText = "select isnull(object_id('表格'),-1)"; 
                object obj= command.ExecuteScalar(); 
                bool b = Convert.ToInt32(obj.ToString()) >= 0; 
                Console.WriteLine(b?"a":"b"); 
            } 
            conn.Close(); 
        }