(1)实体类是业务对象的基础,它用面向对象的思想消除了关系数据与对象之间的差异
实体类:
public class Department { public int BId { get; set; } public int BName{ get; set; } }
public class Employee { public int YId{ get; set; } public int YName{ get; set; } public int BId{ get; set; } public int ZId{ get; set; } }
public class Task { public string Contents {get;set;} public int RId {get;set;} public int YId {get;set;} public DateTime Time {get;set;} public int Hours {get;set;} public string Type { get; set; } }
数据访问层:
public class InfoAddDAL { public bool Add(string name) { bool falg = false; string sql = "insert into ProgramInfo(pname) values('"+name+"')"; int num=SQLHelper.ExecuteNonQuery(sql); if(num==1) { falg= true; } return falg; } public DataTable SelectInfo() { List<string> list = new List<string>(); try { string sql = "select pname from ProgramInfo"; DataTable table=SQLHelper.ExecuteDataTable(sql); return table; } catch (SqlException ex) { throw ex; } catch(Exception ex) { throw ex; } } public bool DeleteInfo(string name) { bool falg = false; try { string sql = "delete ProgramInfo where pname='" + name + "'"; int num=SQLHelper.ExecuteNonQuery(sql); if (num == 1) { falg= true; } return falg; } catch (SqlException ex) { throw ex; } catch(Exception ex) { throw ex; } } public bool UpdateInfo(string name,string names) { bool falg = false; string sql = "Update ProgramInfo set pname='"+name+"'where pname='"+names+"'"; int num=SQLHelper.ExecuteNonQuery(sql); if(num==1) { falg= true; } return falg; } }
在这里再引用一个App.config
<?xml version="1.0" encoding="utf-8" ?> <configuration> <connectionStrings> <add name="constr" connectionString="data source=.; initial catalog=AddInfo; uid=sa;"> </add> </connectionStrings> <startup> <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" /> </startup> </configuration>
(2)const和readonly的区别
(1)readonly只能修饰类变量 const修饰成员变量和局部变量
(2)readonly在运行时赋值,const在编译时赋值
(3)const只能修饰值类型和特殊的引用类型 readonly可以修饰任何类型