拉姆达语句

1、Queryable 用于拉姆达表达式操作

1、Queryable 用于拉姆达表达式操作
//---------Queryable<T>,扩展函数查询---------//
//---------Queryable<T>,扩展函数查询---------//

//针对单表或者视图查询

//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10-20条
var page1 = db.Queryable<Student>().Where(c => c.id > 10).OrderBy(it => it.id).Skip(10).Take(20).ToList();

//上一句的简化写法，同样取10-20条
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();

// 可以在拉姆达使用 ToString和 Convert,比EF出色的地方
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 => DateTime.Now > Convert.ToDateTime("2015-1-1")).ToList();
var convert4 = db.Queryable<Student>().Where(c => DateTime.Now > DateTime.Now).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>100").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<Student, 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<Student, 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 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();

//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<SexTotal> list9 = db.Queryable<Student>().Where(c => c.id < 20).GroupBy(it => it.sex).Select<Student, SexTotal>("Sex,Count=count(*)").ToList();
List<SexTotal> list10 = db.Queryable<Student>().Where(c => c.id < 20).GroupBy("sex").Select<Student, SexTotal>("Sex,Count=count(*)").ToList();
//SELECT Sex,Count=count(*) FROM Student WHERE 1=1 AND (id < 20) GROUP BY Sex --生成结果

2、SqlQuery 用于执行原生SQL和存储过程

//转成list
List<Student> list1 = db.SqlQuery<Student>("select * from Student");
//转成list带参
List<Student> list2 = db.SqlQuery<Student>("select * from Student where id=@id", new { id = 1 });
//转成dynamic
dynamic list3 = db.SqlQueryDynamic("select * from student");
//转成json
string list4 = db.SqlQueryJson("select * from student");
//返回int
var list5 = db.SqlQuery<int>("select top 1 id from Student").SingleOrDefault();
//反回键值
Dictionary<string, string> list6 = db.SqlQuery<KeyValuePair<string, string>>("select id,name from Student").ToDictionary(it => it.Key, it => it.Value);
//反回List<string[]>
var list7 = db.SqlQuery<string[]>("select top 1 id,name from Student").SingleOrDefault();
//存储过程
var spResult = db.SqlQuery<School>("exec sp_school @p1,@p2", new { p1 = 1, p2 = 2 });

//获取第一行第一列的值
string v1 = db.GetString("select '张三' as name");
int v2 = db.GetInt("select 1 as name");
double v3 = db.GetDouble("select 1 as name");
decimal v4 = db.GetDecimal("select 1 as name");

3、Sqlable 更贴近SQL的一种编程方式，适用于复杂查询 / Complex query

//---------Sqlable,创建多表查询---------//

//多表查询
List<School> dataList = db.Sqlable()
.From("school", "s")
.Join("student", "st", "st.id", "s.id", JoinType.INNER)
.Join("student", "st2", "st2.id", "st.id", JoinType.LEFT)
.Where("s.id>100 and s.id<@id")
.Where("1=1")//可以多个WHERE
.SelectToList<School/*新的Model我这里没有所以写的School*/>("st.*", new { id = 1 });

//多表分页
List<School> dataPageList = db.Sqlable()
.From("school", "s")
.Join("student", "st", "st.id", "s.id", JoinType.INNER)
.Join("student", "st2", "st2.id", "st.id", JoinType.LEFT)
.Where("s.id>100 and s.id<100")
.SelectToPageList<School>("st.*", "s.id", 1, 10);

//多表分页WHERE加子查询
List<School> dataPageList2 = db.Sqlable()
.From("school", "s")
.Join("student", "st", "st.id", "s.id", JoinType.INNER)
.Join("student", "st2", "st2.id", "st.id", JoinType.LEFT)
.Where("s.id>100 and s.id<100 and s.id in (select 1 )" /*这里面写子查询都可以*/)
.SelectToPageList<School>("st.*", "s.id", 1, 10);

 

//--------转成List Dynmaic 或者 Json-----//

//不分页
var list1 = db.Sqlable().From("student", "s").Join("school", "l", "s.sch_id", "l.id and l.id=@id", JoinType.INNER).SelectToDynamic("*", new { id = 1 });
var list2 = db.Sqlable().From("student", "s").Join("school", "l", "s.sch_id", "l.id and l.id=@id", JoinType.INNER).SelectToJson("*", new { id = 1 });
var list3 = db.Sqlable().From("student", "s").Join("school", "l", "s.sch_id", "l.id and l.id=@id", JoinType.INNER).SelectToDataTable("*", new { id = 1 });

//分页
var list4 = db.Sqlable().From("student", "s").Join("school", "l", "s.sch_id", "l.id and l.id=@id", JoinType.INNER).SelectToPageDynamic("s.*", "l.id", 1, 10, new { id = 1 });
var list5 = db.Sqlable().From("student", "s").Join("school", "l", "s.sch_id", "l.id and l.id=@id", JoinType.INNER).SelectToPageTable("s.*", "l.id", 1, 10, new { id = 1 });
var list6 = db.Sqlable().From("student", "s").Join("school", "l", "s.sch_id", "l.id and l.id=@id", JoinType.INNER).SelectToPageDynamic("s.*", "l.id", 1, 10, new { id = 1 });


//--------拼接-----//
Sqlable sable = db.Sqlable().From<Student>("s").Join<School>("l", "s.sch_id", "l.id", JoinType.INNER);
string name = "a";
int id = 1;
if (!string.IsNullOrEmpty(name))
{
sable = sable.Where("s.name=@name");
}
if (!string.IsNullOrEmpty(name))
{
sable = sable.Where("s.id=@id or s.id=100");
}
if (id > 0)
{
sable = sable.Where("l.id in (select top 10 id from school)");//where加子查询
}
var pars = new { id = id, name = name };
int pageCount = sable.Count(pars);
var list7 = sable.SelectToPageList<Student>("s.*","l.id desc",1,20, pars);

4、新容器转换 / To new container

using (SqlSugarClient db = SugarDao.GetInstance())
{
var list2 = db.Queryable<Student>().Where(c => c.id < 10).Select(c => new classNew { newid = c.id, newname = c.name, xx_name = c.name }).ToList();//不支持匿名类转换,也不建议使用

var list3 = db.Queryable<Student>().Where(c => c.id < 10).Select(c => new { newid = c.id, newname = c.name, xx_name = c.name }).ToDynamic();//匿名类转换

var list4 = db.Queryable<Student>().Where(c => c.id < 10).Select("id as newid, name as newname ,name as xx_name").ToDynamic();//匿名类转换
}

添加/Add

using (SqlSugarClient db = SugarDao.GetInstance())//开启数据库连接
{
Student s = new Student()
{
name = "张" + new Random().Next(1, int.MaxValue)
};

db.Insert(s); //插入一条记录 (有主键也好，没主键也好，有自增列也好都可以插进去)


List<Student> list = new List<Student>()
{
new Student()
{
name="张"+new Random().Next(1,int.MaxValue)
},
new Student()
{
name="张"+new Random().Next(1,int.MaxValue)
}
};

db.InsertRange(list); //批量插入
}
}

更新/Update

using (var db = SugarDao.GetInstance())
{
//指定列更新
db.Update<School>(new { name = "蓝翔2" }, it => it.id == id);
db.Update<School, int>(new { name = "蓝翔2" }, 1, 3, 12);
db.Update<School, string>(new { name = "蓝翔2" }, new string[] { "1", "2" });

//整个实体更新
db.Update(new School { id = id, name = "蓝翔2" });
db.Update<School>(new School { id = id, name = "蓝翔2" }, it => it.id == id);


//设置不更新列
db.DisableUpdateColumns = new string[] { "CreateTime" };//设置CreateTime不更新

TestUpdateColumns updObj = new TestUpdateColumns()
{
VGUID = Guid.Parse("542b5a27-6984-47c7-a8ee-359e483c8470"),
Name = "xx",
Name2 = "xx2",
IdentityField = 0,
CreateTime = null
};

//CreateTime将不会被更新
db.Update(updObj);
//以前实现这种更新需要用指定列的方式实现，现在就简单多了。

}

删除和假删除/Delete And False Delete

using (var db = SugarDao.GetInstance())
{
//真删除
db.Delete<School, int>(10);//注意主键必需为实体类的第一个属性
db.Delete<School>(it => it.id > 100);
db.Delete<School, string>(new string[] { "100", "101", "102" });

//假删除
//db.FalseDelete<school>("is_del", 100);
//等同于 update school set is_del=0 where id in(100)
//db.FalseDelete<school>("is_del", it=>it.id==100);
}