.NET Core C#系列之XiaoFeng.Data.IQueryableX ORM框架

/// <summary> /// 分类模型 /// </summary> [Table("Category","分类", "CategoryId",ModelType.Model,"FayElf.Web",0)] public class Category : Entity<Category> {     #region 构造器     /// <summary>     /// 无参构造器     /// </summary>     public Category()     {      }     #endregion      #region 属性     /// <summary>     /// 分类名称     /// </summary>     [Column(Name="Names")] 	public string Name { get; set; }     /// <summary>     /// 分类说明     /// </summary>     public string Description { get; set; }     /// <summary>     /// 分类ID     /// </summary>     public int CategoryId { get; set; }     /// <summary>     /// 父节点ID     /// </summary>     public int ParentId { get; set; }     /// <summary>     /// 添加日期     /// </summary>     public DateTime AddDate { get; set; }     #endregion      #region 方法      #endregion }

/// <summary> /// 用户模型 /// </summary> public class UserModel {     #region 构造器     /// <summary>     /// 无参构造器     /// </summary>     public UserModel()     {      }     #endregion      #region 属性     /// <summary>     /// Id     /// </summary>     public long Id { get; set; }     /// <summary>     /// 帐号     /// </summary>     public string Account { get; set; }     /// <summary>     /// 密码     /// </summary>     public string Password { get; set; }     /// <summary>     /// 性别     /// </summary>     public int Sex { get; set; }     /// <summary>     /// 出生日期     /// </summary>     public DateTime BirthDay { get; set; }     /// <summary>     /// 添加日期     /// </summary>     public DateTime AddDate { get; set; }     #endregion      #region 方法      #endregion }

//首选实例化一个 Category 实例 var category = Category.Create; //查询 var category1 = category.Find(a => a.CategoryId == 2); var category2 = category.Where(a => a.CategoryId == 2).ToEntity(); //上边两种方式是一样的 都是提取 CategoryId 等于 2 的一条数据 //列表 var category3 = category.Where(a => a.CategoryId == 3).ToList(); var category4 = category.ToList(a => a.CategoryId == 3); //上边两种方式是一样的 都是提取 CategoryId 等于 3 的列表数据 //删除 //当前语句是删除 CateogryId 等于 4 的这条记录 var delete5 = category.Where(a => a.CategoryId == 4).Delete(); //当前语句是删除查从库中查出来的一条数据给删除掉 var delete6 = category1.Delete();  //插入 new Category {     Name="a", ParentId=0 }.Insert(); //更新 //当前语句是更新字段 为 Name ParentId 的字段值 条件是 CategoryId 等于 5 的记录 var update5 = category.Where(a => a.CategoryId == 5).Update(a => a.Name == "aaa" && a.ParentId == 10); //当前语句是更新 字段 Name ParentId的值 数据是上边查询出来的一条记录 category1.Name = "bbbb"; category1.ParentId = 3; var update6 = category.Update();  //联表 下边用法就是 通过 左关联 两张表 on 条件是 第一张表的 ParentId 与第二张表的 CategoryId 相同 然后字段显示为 Name,CategoryId,ParentName 的列表 var join1 = category.QueryableX.Join<Category, object[]>((a, b) => new object[] { JoinType.Left, a.ParentId == b.CategoryId }).Select((a, b) => new {     a.Name,     a.CategoryId,     ParentName = b.Name }).ToList(); //更多表关联 有两种方法 第一种是 两张表关联的结果和第三张表关联，再关联的结果与第四经表关联 依次类推 //第二种方法就是 假设一共有5张表关联那么直接实例化 DataHelperX时直接关联5张表，建议用第一种方法。

//创建一个带数据库的 IQueryableX 对象，下边所有的操作都是基于当前对象来操作。 var data = new DataHelperX<UserModel>(Conn); //查询  下边三种写法 运行后 结果是一样的 var userModel1 = data.Where(a => a.Account == "jacky" && a.Password == "admin123").ToEntity(); var userModel2 = data.Where(a => a.Account == "jacky").Where(a => a.Password == "admin123").ToEntity(); var userModel3 = data.First(a => a.Account == "jacky" && a.Password == "admin123"); //列表 var userList1 = data.Where(a => a.Sex == 1 || a.Account == "jacky").ToList(); //关联查询 var userList2 = data.Where(a => a.Sex == 1).Join<UserModel, object[]>((a, b) => new object[] { a.Account == b.Password }).Select((a, b) => new {     a.Account,     a.Password,     ParentName = b.Account }).ToList(); //插入 var userModel4 = new UserModel { Account = "jacky", Password = "admin" }; var insert1 = data.Insert(userModel4); //如果想返回自增长ID则后边输入接收参数即可如下 var insert2 = data.Insert(userModel4, out var ID);  //批量插入 var insert3 = data.Inserts(new List<UserModel> { userModel4,userModel4 });  //更新 var update1 = data.Where(a => a.Id == 1).Update(a => a.Password == "adminadmin");  //删除 var delete1 = data.Where(a => a.Id == 1).Delete();

/// <summary> /// 扩展SQL语法 /// Version : 2.0.0 /// Author : jacky /// Email : jacky@zhuovi.com /// QQ : 7092734 /// Site : www.zhuovi.com /// Create Time : 2017/12/20 9:40:00 /// Update Time : 2018/01/19 13:40:00 /// </summary> public static partial class PrototypeHelper {     #region 扩展SQL 语法      #region 扩展SQL 字段加值+     /// <summary>     /// 字段加值     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="value">值</param>     /// <returns></returns>     public static T AddSQL<T>(this T obj, T value) { return obj; }     #endregion      #region 扩展SQL 字段减值-     /// <summary>     /// 字段减值     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="value">值</param>     /// <returns></returns>     public static T SubtractSQL<T>(this T obj, T value) { return obj; }     #endregion      #region 扩展SQL 字段乘值*     /// <summary>     /// 字段乘值     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]     public static T MultiplySQL<T>(this T obj, T value) { return obj; }     #endregion      #region 扩展SQL 字段除值/     /// <summary>     /// 字段除值     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static T DivideSQL<T>(this T obj, T value) { return obj; }     #endregion      #region 扩展SQL Between     /// <summary>     /// 扩展SQL Between     /// </summary>     /// <param name="obj">对象</param>     /// <param name="startValue">开始值</param>     /// <param name="endValue">结束值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Boolean BetweenSQL(this object obj, object startValue, object endValue) { return true; }     #endregion      #region 扩展SQL ISNULL     /// <summary>     /// 扩展SQL ISNULL     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="defaultValue">默认值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static T IsNullSQL<T>(this T obj, T defaultValue) { return defaultValue; }     #endregion      #region 扩展SQL in 语法     /// <summary>     /// 扩展SQL in语法     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="array">数组织</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static bool InSQL<T>(this T obj, IEnumerable<T> array) { return true; }     /// <summary>     /// 扩展SQL in语法     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="array">数组织</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static bool InSQL<T>(this T obj, T[] array) { return true; }     /// <summary>     /// 扩展SQL in语法     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <typeparam name="T1">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="queryableX">IQueryableX对象</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Boolean InSQL<T, T1>(this T obj, IQueryableX<T1> queryableX) { return true; }     /// <summary>     /// 扩展SQL in语法     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="array">数组</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static bool InSQL<T>(this T obj, object[] array) { return true; }     /// <summary>     /// 扩展SQL not in语法     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="array">数组</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static bool NotInSQL<T>(this T obj, IEnumerable<T> array) { return true; }     /// <summary>     /// 扩展SQL not in语法     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="array">数组</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static bool NotInSQL<T>(this T obj, T[] array) { return true; }     /// <summary>     /// 扩展SQL not in语法     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <typeparam name="T1">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="queryableX">IQueryableX对象</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Boolean NotInSQL<T, T1>(this T obj, IQueryableX<T1> queryableX) { return true; }     /// <summary>     /// 扩展SQL not in语法     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="array">数组</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static bool NotInSQL<T>(this T obj, object[] array) { return true; }     #endregion      #region 扩展SQL like 语法     /// <summary>     /// 扩展SQL like 语法     /// </summary>     /// <param name="str">字符串</param>     /// <param name="likeStr">子串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static bool LikeSQL(this object str, string likeStr) { return true; }     /// <summary>     /// 扩展SQL not like 语法     /// </summary>     /// <param name="str">字符串</param>     /// <param name="likeStr">子串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static bool NotLikeSQL(this string str, string likeStr) { return true; }     /// <summary>     /// 扩展SQL like 语法     /// </summary>     /// <param name="str">字符串</param>     /// <param name="likeStr">子串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]     public static bool LikeSQLX(this object str, string likeStr) { return true; }     /// <summary>     /// 扩展SQL not like 语法     /// </summary>     /// <param name="str">字符串</param>     /// <param name="likeStr">子串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]     public static bool NotLikeSQLX(this string str, string likeStr) { return true; }     #endregion      #region 扩展SQL DateAdd 语法     /// <summary>     /// 扩展SQL DateAdd 语法     /// </summary>     /// <param name="date">日期</param>     /// <param name="val">值</param>     /// <param name="format">格式 年yy,yyyy 季度qq,q 月mm,m 年中的日dy,y 日dd,d 周wk,ww 星期dw,w 小时hh 分钟mi,n 秒ss,s 毫秒ms 微秒mcs 纳秒ns</param>     /// <returns></returns>     public static DateTime DateAddSQL(this DateTime date, long val, string format)     {         return date;     }     /// <summary>     /// 扩展SQL DateAdd 语法     /// </summary>     /// <param name="date">日期</param>     /// <param name="val">值</param>     /// <param name="format">格式 年yy,yyyy 季度qq,q 月mm,m 年中的日dy,y 日dd,d 周wk,ww 星期dw,w 小时hh 分钟mi,n 秒ss,s 毫秒ms 微秒mcs 纳秒ns</param>     /// <returns></returns>     public static DateTime DateAddSQL(this DateTime? date, long val, string format)     {         return date.GetValueOrDefault();     }     #endregion      #region 扩展SQL DateDiff 语法     /// <summary>     /// 扩展SQL DateDiff 语法     /// </summary>     /// <param name="firstDate">第一个时间</param>     /// <param name="SecondDate">第二个时间</param>     /// <param name="format">格式 年yy,yyyy 季度qq,q 月mm,m 年中的日dy,y 日dd,d 周wk,ww 星期dw,w 小时hh 分钟mi,n 秒ss,s 毫秒ms 微秒mcs 纳秒ns</param>     /// <returns></returns>     public static int DateDiffSQL(this DateTime? firstDate, DateTime? SecondDate, string format) { return 1; }     /// <summary>     /// 扩展SQL DateDiff 语法     /// </summary>     /// <param name="firstDate">第一个时间</param>     /// <param name="SecondDate">第二个时间</param>     /// <param name="format">格式 年yy,yyyy 季度qq,q 月mm,m 年中的日dy,y 日dd,d 周wk,ww 星期dw,w 小时hh 分钟mi,n 秒ss,s 毫秒ms 微秒mcs 纳秒ns</param>     /// <returns></returns>     public static int DateDiffSQL(this DateTime firstDate, DateTime SecondDate, string format) { return 1; }     #endregion      #region 扩展SQL DatePart 语法     /// <summary>     /// 扩展SQL DatePart 语法     /// </summary>     /// <param name="Date">当前时间</param>     /// <param name="format">格式 年yy,yyyy 季度qq,q 月mm,m 年中的日dy,y 日dd,d 周wk,ww 星期dw,w 小时hh 分钟mi,n 秒ss,s 毫秒ms 微秒mcs 纳秒ns</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static int DatePartSQL(this DateTime? Date, string format) { return 0; }     /// <summary>     /// 扩展SQL DatePart 语法     /// </summary>     /// <param name="Date">当前时间</param>     /// <param name="format">格式 年yy,yyyy 季度qq,q 月mm,m 年中的日dy,y 日dd,d 周wk,ww 星期dw,w 小时hh 分钟mi,n 秒ss,s 毫秒ms 微秒mcs 纳秒ns</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static int DatePartSQL(this DateTime Date, string format) { return 0; }     #endregion      #region 扩展SQL DateFormat 语法     /// <summary>     /// 扩展SQL DateFormat 语法     /// </summary>     /// <param name="Date">当前时间</param>     /// <param name="format"></param>     /// <returns></returns>     public static string DateFormatSQL(this DateTime? Date, string format) { return string.Empty; }     /// <summary>     /// 扩展SQL DateFormat 语法     /// </summary>     /// <param name="Date">当前时间</param>     /// <param name="format"></param>     /// <returns></returns>     public static string DateFormatSQL(this DateTime Date, string format) { return string.Empty; }     #endregion      #region 扩展SQL Charindex 语法     /// <summary>     /// 扩展SQL Charindex 语法     /// </summary>     /// <param name="str">字符串</param>     /// <param name="IndexStr">子串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static int CharIndexSQL(this string str, string IndexStr) { return 1; }     #endregion      #region 扩展SQL Patindex语法     /// <summary>     /// 扩展SQL Patindex语法     /// </summary>     /// <param name="str">字符串</param>     /// <param name="IndexStr">子串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static int PatindexSQL(this string str, string IndexStr) { return 1; }     #endregion      #region 扩展SQL Abs 算法     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static int AbsSQL(this int value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static int AbsSQL(this int? value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Int16 AbsSQL(this Int16? value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Int16 AbsSQL(this Int16 value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Int64 AbsSQL(this Int64? value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Int64 AbsSQL(this Int64 value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Double AbsSQL(this Double? value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Double AbsSQL(this Double value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static decimal AbsSQL(this decimal? value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static decimal AbsSQL(this decimal value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static float AbsSQL(this float? value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static float AbsSQL(this float value) { return 1; }     #endregion      #region 扩展SQL Floor 算法     /// <summary>     /// 扩展SQL Floor 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Double FloorSQL(this Double? value) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Double FloorSQL(this Double value) { return 1; }     /// <summary>     /// 扩展SQL Floor 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static decimal FloorSQL(this decimal? value) { return 1; }     /// <summary>     /// 扩展SQL Floor 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static decimal FloorSQL(this decimal value) { return 1; }     /// <summary>     /// 扩展SQL Floor 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static float FloorSQL(this float? value) { return 1; }     /// <summary>     /// 扩展SQL Floor 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static float FloorSQL(this float value) { return 1; }     #endregion      #region 扩展SQL Ceiling 算法     /// <summary>     /// 扩展SQL Ceiling 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Double CeilingSQL(this Double? value) { return 1; }     /// <summary>     /// 扩展SQL Ceiling 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Double CeilingSQL(this Double value) { return 1; }     /// <summary>     /// 扩展SQL Ceiling 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static decimal CeilingSQL(this decimal? value) { return 1; }     /// <summary>     /// 扩展SQL Ceiling 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static decimal CeilingSQL(this decimal value) { return 1; }     /// <summary>     /// 扩展SQL Ceiling 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static float CeilingSQL(this float? value) { return 1; }     /// <summary>     /// 扩展SQL Ceiling 算法     /// </summary>     /// <param name="value">值</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static float CeilingSQL(this float value) { return 1; }     #endregion      #region 扩展SQL Round 算法     /// <summary>     /// 扩展SQL Round 算法     /// </summary>     /// <param name="value">值</param>     /// <param name="len">小数点保留长度</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Double RoundSQL(this Double? value, int len) { return 1; }     /// <summary>     /// 扩展SQL Round 算法     /// </summary>     /// <param name="value">值</param>     /// <param name="len">小数点保留长度</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static Double RoundSQL(this Double value, int len) { return 1; }     /// <summary>     /// 扩展SQL Round 算法     /// </summary>     /// <param name="value">值</param>     /// <param name="len">小数点保留长度</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static decimal RoundSQL(this decimal? value, int len) { return 1; }     /// <summary>     /// 扩展SQL Round 算法     /// </summary>     /// <param name="value">值</param>     /// <param name="len">小数点保留长度</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static decimal RoundSQL(this decimal value, int len) { return 1; }     /// <summary>     /// 扩展SQL Abs 算法     /// </summary>     /// <param name="value">值</param>     /// <param name="len">小数点保留长度</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static float RoundSQL(this float? value, int len) { return 1; }     /// <summary>     /// 扩展SQL Round 算法     /// </summary>     /// <param name="value">值</param>     /// <param name="len">小数点保留长度</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static float RoundSQL(this float value, int len) { return 1; }     #endregion      #region 扩展SQL Left     /// <summary>     /// 扩展SQL Left     /// </summary>     /// <param name="str">字符串</param>     /// <param name="num">第几位</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string LeftSQL(this string str, int num) { return ""; }     #endregion      #region 扩展SQL Right     /// <summary>     /// 扩展SQL Right     /// </summary>     /// <param name="str">字符串</param>     /// <param name="num">第几位</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string RightSQL(this string str, int num) { return ""; }     #endregion      #region 扩展SQL Len     /// <summary>     /// 扩展SQL Len     /// </summary>     /// <param name="str">字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static int LengthSQL(this string str) { return 1; }     #endregion      #region 扩展SQL Replace     /// <summary>     /// 扩展SQL Replace     /// </summary>     /// <param name="str">字符串</param>     /// <param name="oldString">原字符串</param>     /// <param name="replaceString">新字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string ReplaceSQL(this string str, string oldString, string replaceString) { return ""; }     #endregion      #region 扩展SQL Replicate     /// <summary>     /// 扩展SQL Replicate     /// </summary>     /// <param name="str">字符串</param>     /// <param name="num">重复次数</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string ReplicateSQL(this string str, int num) { return ""; }     #endregion      #region 扩展SQL Reverse     /// <summary>     /// 扩展SQL Reverse     /// </summary>     /// <param name="str">字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string ReverseSQL(this string str) { return ""; }     #endregion      #region 扩展SQL Stuff     /// <summary>     /// 扩展SQL Stuff     /// </summary>     /// <param name="str">字符串</param>     /// <param name="strat">开始位置</param>     /// <param name="length">长度</param>     /// <param name="replaceString">替换字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string StuffSQL(this string str, int strat, int length, string replaceString) { return ""; }     #endregion      #region 扩展SQL Substring     /// <summary>     /// 扩展SQL Substring     /// </summary>     /// <param name="str">字符串</param>     /// <param name="start">开始位置</param>     /// <param name="length">长度</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string SubstringSQL(this string str, int start, int length) { return ""; }     #endregion      #region 扩展SQL Trim     /// <summary>     /// 扩展SQL Ltrim     /// </summary>     /// <param name="str">字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string LTrimSQL(this string str) { return ""; }     /// <summary>     /// 扩展SQL Rtrim     /// </summary>     /// <param name="str">字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string RTrimSQL(this string str) { return ""; }     /// <summary>     /// 扩展SQL Trim     /// </summary>     /// <param name="str">字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string TrimSQL(this string str) { return ""; }     #endregion      #region 扩展SQL Lower     /// <summary>     /// 扩展SQL Lower     /// </summary>     /// <param name="str">字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string LowerSQL(this string str) { return ""; }     #endregion      #region 扩展SQL Upper     /// <summary>     /// 扩展SQL Upper     /// </summary>     /// <param name="str">字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static string UpperSQL(this string str) { return ""; }     #endregion      #region 扩展SQL Count     /// <summary>     /// 扩展SQL Count     /// </summary>     /// <param name="str">字符串</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static int CountSQL(this object str) { return 0; }     #endregion      #region 扩展SQL MAX     /// <summary>     /// 扩展SQL MAX     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">字符串</param>     /// <returns></returns>     public static T MaxSQL<T>(this T obj) { return obj; }     #endregion      #region 扩展SQL MIN     /// <summary>     /// 扩展SQL MIN     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">字符串</param>     /// <returns></returns>     public static T MinSQL<T>(this T obj) { return obj; }     #endregion      #region 扩展SQL SUM     /// <summary>     /// 扩展SQL SUM     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">字符串</param>     /// <returns></returns>     public static T SumSQL<T>(this T obj) { return obj; }     #endregion      #region 扩展SQL AVG     /// <summary>     /// 扩展SQL AVG     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">字符串</param>     /// <returns></returns>     public static T AvgSQL<T>(this T obj) { return obj; }     #endregion      #region 设置字段别名     /// <summary>     /// 设置字段别名     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="ColumnName">别名</param>     /// <returns></returns>     [System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0060:删除未使用的参数", Justification = "<挂起>")]      public static T As<T>(this T obj, string ColumnName) { return obj; }     #endregion      #region 转换类型     /// <summary>     /// 转换类型     /// </summary>     /// <typeparam name="T">类型</typeparam>     /// <param name="obj">对象</param>     /// <param name="dataType">目标类型</param>     /// <returns></returns>     public static T CastSQL<T>(this T obj,string dataType) { return obj; }     #endregion      #region SQL参数化调整     /// <summary>     /// SQL参数化调整     /// </summary>     /// <param name="_">SQL语句</param>     /// <param name="dbProvider">数据库驱动</param>     /// <returns></returns>     public static string SQLFormat(this string _, DbProviderType dbProvider)     {         switch (dbProvider)         {             case DbProviderType.Dameng:                 return _.ReplacePattern(@"@((Sub_(d+_)?)?ParamNamed+)", "?");             case DbProviderType.Oracle:                 return _.ReplacePattern(@"@((Sub_(d+_)?)?ParamNamed+)", ":$1");         }         return _;     }     #endregion      #endregion }

//内部方法 //查询出分类名称前边包含 字符串 a 的数据 var category5 = category.Where(a => a.Name.StartsWith("a")).ToList(); //查询出分类名第2位开始4个长度的字符是abcd的数据 var category6 = category.Where(a => a.Name.Substring(2, 4) == "abcd").ToList(); //查询 出分类表中添加时间比现在时间少3个时小的 数据 var category7 = category.Where(a => a.AddDate.DateDiffSQL(DateTime.Now, "hh") == 3).ToList();

if(exists(select top 1 from TestTb where ID = 1)) 	delete from testTb where ID = 1;