/// <summary> /// 拉姆达表达示 /// </summary> private void QueryableDemo() { using (var db = SugarDao.GetInstance()) { //查询所有 var student = db.Queryable <Student>().ToList(); var studentDynamic = db.Queryable <Student>().ToDynamic(); var studentJson = db.Queryable <Student>().ToJson(); //查询单条 var single = db.Queryable <Student>().Single(c => c.id == 1); //查询单条根据主键 var singleByPk = db.Queryable <Student>().InSingle(1); //查询单条没有记录返回空对象 var singleOrDefault = db.Queryable <Student>().SingleOrDefault(c => c.id == 11111111); //查询单条没有记录返回空对象 var single2 = db.Queryable <Student>().Where(c => c.id == 1).SingleOrDefault(); //查询第一条 var first = db.Queryable <Student>().Where(c => c.id == 1).First(); var first2 = db.Queryable <Student>().Where(c => c.id == 1).FirstOrDefault(); //取11-20条 var page1 = db.Queryable <Student>().Where(c => c.id > 10).OrderBy(it => it.id).Skip(10).Take(10).ToList(); //取11-20条 等于 Skip(pageIndex-1)*pageSize).Take(pageSize) 等于 between (pageIndex-1)*pageSize and pageIndex*pageSize var page2 = db.Queryable <Student>().Where(c => c.id > 10).OrderBy(it => it.id).ToPageList(2, 10); //查询条数 var count = db.Queryable <Student>().Where(c => c.id > 10).Count(); //从第2条开始以后取所有 var skip = db.Queryable <Student>().Where(c => c.id > 10).OrderBy(it => it.id).Skip(2).ToList(); //取前2条 var take = db.Queryable <Student>().Where(c => c.id > 10).OrderBy(it => it.id).Take(2).ToList(); //Not like string conval = "a"; var notLike = db.Queryable <Student>().Where(c => !c.name.Contains(conval.ToString())).ToList(); //Like conval = "三"; var like = db.Queryable <Student>().Where(c => c.name.Contains(conval)).ToList(); //支持字符串Where 让你解决,更复杂的查询 var student12 = db.Queryable <Student>().Where(c => "a" == "a").Where("id>@id", new { id = 1 }).ToList(); var student13 = db.Queryable <Student>().Where(c => "a" == "a").Where("id>100 and id in( select 1)").ToList(); //存在记录反回true,则否返回false bool isAny100 = db.Queryable <Student>().Any(c => c.id == 100); bool isAny1 = db.Queryable <Student>().Any(c => c.id == 1); //获取最大Id object maxId = db.Queryable <Student>().Max(it => it.id); int maxId1 = db.Queryable <Student>().Max(it => it.id).ObjToInt(); //拉姆达 int maxId2 = db.Queryable <Student>().Max <int>("id"); //字符串写法 //获取最小 int minId1 = db.Queryable <Student>().Where(c => c.id > 0).Min(it => it.id).ObjToInt(); //拉姆达 int minId2 = db.Queryable <Student>().Where(c => c.id > 0).Min <int>("id"); //字符串写法 //order By var orderList = db.Queryable <Student>().OrderBy("id desc,name asc").ToList(); //字符串支持多个排序 //可以多个order by表达示 var order2List = db.Queryable <Student>().OrderBy(it => it.name).OrderBy(it => it.id, OrderByType.desc).ToList(); // order by name as ,order by id desc //In var intArray = new[] { "5", "2", "3" }; var intList = intArray.ToList(); var listnew = db.Queryable <Student>().Where(it => intArray.Contains(it.name)).ToList(); var list0 = db.Queryable <Student>().In(it => it.id, 1, 2, 3).ToList(); var list1 = db.Queryable <Student>().In(it => it.id, intArray).ToList(); var list2 = db.Queryable <Student>().In("id", intArray).ToList(); var list3 = db.Queryable <Student>().In(it => it.id, intList).ToList(); var list4 = db.Queryable <Student>().In("id", intList).ToList(); var list6 = db.Queryable <Student>().In(intList).ToList();//不设置字段默认主键 //分组查询 var list7 = db.Queryable <Student>().Where(c => c.id < 20).GroupBy(it => it.sex).Select("sex,count(*) Count").ToDynamic(); var list8 = db.Queryable <Student>().Where(c => c.id < 20).GroupBy(it => it.sex).GroupBy(it => it.id).Select("id,sex,count(*) Count").ToDynamic(); List <StudentGroup> list9 = db.Queryable <Student>().Where(c => c.id < 20).GroupBy(it => it.sex).Select <StudentGroup>("Sex,count(*) Count").ToList(); List <StudentGroup> list10 = db.Queryable <Student>().Where(c => c.id < 20).GroupBy("sex").Select <StudentGroup>("Sex,count(*) Count").ToList(); //SELECT Sex,Count=count(*) FROM Student WHERE 1=1 AND (id < 20) GROUP BY Sex --生成结果 //2表关联查询 var jList = db.Queryable <Student>() .JoinTable <School>((s1, s2) => s1.sch_id == s2.id) //默认left join .Where <School>((s1, s2) => s1.id == 1) .Select("s1.*,s2.name as schName") .ToDynamic(); /*等于同于 * SELECT s1.*,s2.name as schName * FROM [Student] s1 * LEFT JOIN [School] s2 ON s1.sch_id = s2.id * WHERE s1.id = 1 */ //2表关联查询并分页 var jList2 = db.Queryable <Student>() .JoinTable <School>((s1, s2) => s1.sch_id == s2.id) //默认left join //如果要用inner join这么写 //.JoinTable<School>((s1, s2) => s1.sch_id == s2.id ,JoinType.INNER) .Where <School>((s1, s2) => s1.id > 1) .OrderBy(s1 => s1.name) .Skip(10) .Take(20) .Select("s1.*,s2.name as schName") .ToDynamic(); //3表查询并分页 var jList3 = db.Queryable <Student>() .JoinTable <School>((s1, s2) => s1.sch_id == s2.id) // left join School s2 on s1.id=s2.id .JoinTable <School>((s1, s3) => s1.sch_id == s3.id) // left join School s3 on s1.id=s3.id .Where <School>((s1, s2) => s1.id > 1) // where s1.id>1 .Where(s1 => s1.id > 0) .OrderBy <School>((s1, s2) => s1.id) //order by s1.id 多个order可以 .oderBy().orderby 叠加 .Skip(10) .Take(20) .Select("s1.*,s2.name as schName,s3.name as schName2")//select目前只支持这种写法 .ToDynamic(); //上面的方式都是与第一张表join,第三张表想与第二张表join写法如下 List <V_Student> jList4 = db.Queryable <Student>() .JoinTable <School>((s1, s2) => s1.sch_id == s2.id) // left join School s2 on s1.id=s2.id .JoinTable <School, Area>((s1, s2, a1) => a1.id == s2.AreaId) // left join Area a1 on a1.id=s2.AreaId 第三张表与第二张表关联 .JoinTable <Area, School>((s1, a1, s3) => a1.id == s3.AreaId) // left join School s3 on a1.id=s3.AreaId 第四第表第三张表关联 .JoinTable <School>((s1, s4) => s1.sch_id == s4.id) // left join School s2 on s1.id=s4.id .Select <School, Area, V_Student>((s1, s2, a1) => new V_Student { id = s1.id, name = s1.name, SchoolName = s2.name, AreaName = a1.name }).ToList(); //等同于 //SELECT id = s1.id, name = s1.name, SchoolName = s2.name, AreaName = a1.name //FROM [Student] s1 //LEFT JOIN School s2 ON ( s1.sch_id = s2.id ) //LEFT JOIN Area a1 ON ( a1.id = s2.AreaId ) //第三张表与第二张表关联 //LEFT JOIN School s3 ON ( a1.id = s3.AreaId ) //第四张表与第三张表关联 //LEFT JOIN School s4 ON ( s1.sch_id = s4.id ) //WHERE 1=1 //Join子查询语句加分页的写法 var childQuery = db.Queryable <Area>().Where("id=@id").Select(it => new { id = it.id }).ToSql(); //创建子查询SQL string childTableName = SqlSugarTool.PackagingSQL(childQuery.Key); //将SQL语句用()包成表 var queryable = db.Queryable <Student>() .JoinTable <School>((s1, s2) => s1.sch_id == s2.id) //LEFT JOIN School s2 ON ( s1.sch_id = s2.id ) .JoinTable(childTableName, "a1", "a1.id=s2.areaid", new { id = 1 }, JoinType.INNER) //INNER JOIN (SELECT * FROM [Area] WHERE 1=1 AND id=@id ) a1 ON a1.id=s2.areaid .OrderBy(s1 => s1.id); var list = queryable.Select <School, Area, V_Student>((s1, s2, a1) => new V_Student { id = s1.id, name = s1.name, SchoolName = s2.name, AreaName = a1.name }) .ToPageList(0, 200); var count2 = queryable.Count(); //拼接例子 var queryable2 = db.Queryable <Student>().Where(it => true); if (maxId.ObjToInt() == 1) { queryable2.Where(it => it.id == 1); } else { queryable2.Where(it => it.id == 2); } var listJoin = queryable2.ToList(); //queryable和SqlSugarClient解耦 var par = new Queryable <Student>().Where(it => it.id == 1);//声名没有connection对象的Queryable par.DB = db; var listPar = par.ToList(); //查看生成的sql和参数 var id = 1; var sqlAndPars = db.Queryable <Student>().Where(it => it.id == id).OrderBy(it => it.id).ToSql(); //拉姆达支持的函数操作 var par1 = "2015-1-1"; var par2 = " 我 有空格A, "; var r1 = db.Queryable <Student>().Where(it => it.name == par1.ObjToString()).ToList(); //ObjToString会将null转转成"" var r2 = db.Queryable <InsertTest>().Where(it => it.d1 == par1.ObjToDate()).ToList(); var r3 = db.Queryable <InsertTest>().Where(it => it.id == 1.ObjToInt()).ToList(); //ObjToInt会将null转转成0 var r4 = db.Queryable <InsertTest>().Where(it => it.id == 2.ObjToDecimal()).ToList(); var r5 = db.Queryable <InsertTest>().Where(it => it.id == 3.ObjToMoney()).ToList(); var r6 = db.Queryable <InsertTest>().Where(it => it.v1 == par2.Trim()).ToList(); var convert1 = db.Queryable <Student>().Where(c => c.name == "a".ToString()).ToList(); var convert2 = db.Queryable <Student>().Where(c => c.id == Convert.ToInt32("1")).ToList(); var convert3 = db.Queryable <Student>().Where(c => c.name == par2.ToLower()).ToList(); var convert4 = db.Queryable <Student>().Where(c => c.name == par2.ToUpper()).ToList(); var convert5 = db.Queryable <Student>().Where(c => DateTime.Now > Convert.ToDateTime("2015-1-1")).ToList(); var c1 = db.Queryable <Student>().Where(c => c.name.Contains("a")).ToList(); var c2 = db.Queryable <Student>().Where(c => c.name.StartsWith("a")).ToList(); var c3 = db.Queryable <Student>().Where(c => c.name.EndsWith("a")).ToList(); var c4 = db.Queryable <Student>().Where(c => !string.IsNullOrEmpty(c.name)).ToList(); var c5 = db.Queryable <Student>().Where(c => c.name.Equals("小杰")).ToList(); var c6 = db.Queryable <Student>().Where(c => c.name.Length > 4).ToList(); var time = db.Queryable <InsertTest>().Where(c => c.d1 > DateTime.Now.AddDays(1)).ToList(); var time2 = db.Queryable <InsertTest>().Where(c => c.d1 > DateTime.Now.AddYears(1)).ToList(); var time3 = db.Queryable <InsertTest>().Where(c => c.d1 > DateTime.Now.AddMonths(1)).ToList(); } }