SqlSugar ORM 入門篇2 【查詢】 讓我們實現零SQL
SqlSugar在查詢的功能是非常強大的，多表查詢、分頁查詢 、 一對一查詢、二級快取、一對多查、WhenCase等複雜函式、Mapper功能、和拉姆達自定義擴充套件等，用好了是可以做到真正零SQL的一款ORM。
首先將SqlSugar更新到4.8版本，下面我就來一一講解每種查詢的寫法
建立DbContext
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public DbContext()
ConnectionString = "server=.;uid=sa;pwd=sasa;database=SqlSugar4XTest",
true,//開啟自動釋放模式和EF原理一樣我就不多解釋了
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單表的簡單查詢
我們使用的SimpleClient實現了簡單的單表查詢，如何擴充套件SimpleClient可以看我的上一篇文章
//調式程式碼 用來列印SQL
Db.Aop.OnLogExecuting = (sql, pars) =>
{
Console.WriteLine(sql + "\r\n" + Db.Utilities.SerializeObject(pars.ToDictionary(it => it.ParameterName, it => it.Value)));
Console.WriteLine();
};
var data1 = StudentDb.GetById(1);//根據ID查詢
var data2 = StudentDb.GetList();//查詢所有
var data3 = StudentDb.GetList(it => it.Id == 1); //根據條件查詢
var p = new PageModel() { PageIndex=1,PageSize=2};// 分頁查詢
var data4 = StudentDb.GetPageList(it => it.Name == "xx", p);
Console.Write(p.PageCount);//返回總數
// 分頁查詢加排序
var data5 = StudentDb.GetPageList(it => it.Name == "xx", p,it=>it.Name,OrderByType.Asc);
Console.Write(p.PageCount);//返回總數
對於Grid控制元件來說我一般用這個表單封裝好了全部通用
List<IConditionalModel> conModels = new List<IConditionalModel>();
conModels.Add(new ConditionalModel() { FieldName = "id", ConditionalType = ConditionalType.Equal, FieldValue = "1" });//id=1
conModels.Add(new ConditionalModel() { FieldName = "Student.id", ConditionalType = ConditionalType.Equal, FieldValue = "1" });//id=1
conModels.Add(new ConditionalModel() { FieldName = "id", ConditionalType = ConditionalType.Like, FieldValue = "1" });// id like '%1%'
conModels.Add(new ConditionalModel() { FieldName = "id", ConditionalType = ConditionalType.IsNullOrEmpty });
conModels.Add(new ConditionalModel() { FieldName = "id", ConditionalType = ConditionalType.In, FieldValue = "1,2,3" });
conModels.Add(new ConditionalModel() { FieldName = "id", ConditionalType = ConditionalType.NotIn, FieldValue = "1,2,3" });
conModels.Add(new ConditionalModel() { FieldName = "id", ConditionalType = ConditionalType.NoEqual, FieldValue = "1,2,3" });
conModels.Add(new ConditionalModel() { FieldName = "id", ConditionalType = ConditionalType.IsNot, FieldValue = null });// id is not null
var data6 = StudentDb.GetPageList(conModels,p,it=>it.Name,OrderByType.Asc); //組裝條件當查詢條件的 分頁查詢加排序
簡單查詢中拉姆達的使用技巧
基本上和EF差不太多
var data3 = StudentDb.GetList(it => it.Name.Contains("a")); // like %a% 模糊查詢
var p2 = new int[] { 1, 2, 3 };
var data31 = StudentDb.GetList(it => p2.Contains(it.Id)); // id in (1,2,3)
我們還支援了SqlFunc.xxx一串方法來給我們使用，如下用法
var data311 = StudentDb.GetList(it => SqlFunc.Between(it.Id,1,2)); // id between 1 and 2
動態拼表示式查詢
var exp = Expressionable.Create<Student>()
.OrIF(1 == 1, it => it.Id == 11)
.And(it => it.Id == 1)
.AndIF(2 == 2, it => it.Id == 1)
.Or(it => it.Name == "a1").ToExpression();//拼接表示式
var data311 = StudentDb.GetList(exp); // 動態表示式查詢
擴充套件拉姆達方法
例如我們有自定義的SQL函式或者SqlSugar不支援的我們可以自定擴充套件
具體看這個連線 http://www.codeisbug.com/Doc/8/1162
複雜查詢
我們上面看到的簡單查詢底層都是用複雜查詢實現的
var data1 = StudentDb.GetById(1); //等同於 var data2 = Db.Queryable<Student>().Single(it => it.Id == 1);
多表查詢
var list = Db.Queryable<Student, School>((st, sc) => new object[] {
JoinType.Left,st.SchoolId==sc.Id})
.Select((st,sc)=>new{Id=st.Id,Name=st.Name,SchoolName=sc.Name}).ToList();
生成的SQL如下
SELECT [st].[ID] AS [id] ,
[st].[Name] AS [name] ,
[sc].[Name] AS [schoolName] FROM [STudent] st
Left JOIN School sc ON ( [st].[SchoolId] =[sc].[Id])
多表查詢自支援自動填充到ViewModel
var s11 = Db.Queryable<Student, School>((st, sc) => st.SchoolId == sc.Id)
.Select<ViewModelStudent3>().ToList();
public class ViewModelStudent3: Student
{
public string SchoolName { get; set; }
}
生成的Sql如下
SELECT
sc.[Name] AS [SchoolName],--這一列神奇的自動出現了
sc.[Id] AS [scId],
st.[ID] AS [Id],
st.[SchoolId] AS [SchoolId],
st.[Name] AS [Name],
st.[CreateTime] AS [CreateTime]
FROM [STudent] st ,[School] sc WHERE ( [st].[SchoolId] = [sc].[Id])
多表分頁查詢
var list3 = Db.Queryable<Student, School>((st, sc) => new object[] {
JoinType.Left,st.SchoolId==sc.Id
}).Select<ViewModel>()
.ToPageList(pageIndex,pageSize)
子查詢
var getAll = Db.Queryable<Student, School>((st, sc) => new object[] {
JoinType.Left,st.Id==sc.Id})
.Where(st => st.Id == SqlFunc.Subqueryable<School>().Where(s => s.Id == st.Id).Select(s => s.Id))
.ToList();
//生成的MYSQL語句，如果是SqlServer就是TOP 1
SELECT `st`.`ID`,`st`.`SchoolId`,`st`.`Name`,`st`.`CreateTime`
FROM `STudent` st Left JOIN `School` sc ON ( `st`.`ID` = `sc`.`Id` )
WHERE ( `st`.`ID` =(SELECT `Id` FROM `School` WHERE ( `Id` = `st`.`ID` ) limit 0,1))
一對一的查詢
var getAll = Db.Queryable<Student, School>((st, sc) => new object[] {
JoinType.Left,st.Id==sc.Id})
.Select(st =>
new{
name = st.Name,
id = SqlFunc.Subqueryable<School>().Where(s => s.Id == st.Id).Select(s => s.Id)
}).ToList();
本文只講重點，更多多表查詢請看 API
http://www.codeisbug.com/Doc/8/1124
Mapper功能
如果說 .Select() 也可以實現一對一的查詢或者一些SQL函式但是畢竟是用來生成SQL的所以有很多侷限性，Mapper是在查詢出結果後進行處理所以任何C#方法都支援
也更強大
var s12 = db.Queryable<Student, School>((st, sc) => st.SchoolId == sc.Id).Select<ViewModelStudent3>()
.Mapper(it =>
{
it.Name = Md5(it.Name);
//有多少列要處理寫多少列，能用Mapper的就少用Select相容性更好些
}).ToList();
高效能的一對多查詢
我們也可以用Mapper來實現一對多，彌補.Select()不足
var s12 = db.Queryable<Student, School>((st, sc) => st.SchoolId == sc.Id).Select<ViewModelStudent3>()
.Mapper((it, cache) =>
{
var allSchools = cache.GetListByPrimaryKeys<School>(vmodel => vmodel.SchoolId);
//in（ViewModelStudent3[0].SchoolId , ViewModelStudent3[1].SchoolId...）
/*one to many*/
it.Schools = allSchools.Where(i => i.Id == it.SchoolId).ToList();
/*C# syntax conversion*/
it.Name = it.Name == null ? "null" : it.Name;
}).ToList();
一對多查詢的效能可以秒殺其它ORM ，因為生成的SQL只有2條，並且這2條不會多查詢一條沒用的記錄，有幸趣的可以研究一下，其它的都記憶體處理
多Queryable查詢
Union all查詢將結果集合並
var getUnionAllList2 = db.UnionAll(db.Queryable<Student>(), db.Queryable<Student>()).ToList();//union all
兩個Queryable聯表查詢（有人說我只支援12表JOIN，那這樣就可以支援24張表了）
var q1 = db.Queryable<Student, School>((st,sc)=>new object[] {
JoinType.Left,st.SchoolId==sc.Id
}).Select((st, sc) => new ViewModelStudent4() { Id=st.Id, Name=st.Name,SchoolName=sc.Name });
var q2 = db.Queryable<School>();
var innerJoinList = db.Queryable(q1, q2, (j1, j2) => j1.Id == j2.Id).Select((j1, j2) => j1).ToList();//inner join
var leftJoinList = db.Queryable(q1, q2,JoinType.Left, (j1, j2) => j1.Id == j2.Id).Select((j1, j2) => j1).ToList();/
二級快取支援
二級快取功能是對查詢出來的資料進行快取，在快取不失效的情況下，下次同樣的查詢操作都會從快取內讀取
使用快取查詢
var list=db.Queryable<Student, School>((s1, s2) => s1.Id == s2.Id).Select(s1 => s1).WithCache().ToList();//可以設定過期時間WithCache(60)
刪除快取
我們需要刪除快取也相當方便，只需要在對該表操作的時候加 RemoveDataCache 就能把查詢中引用該表的快取全部清除
db.Deleteable<Student>().Where(it => it.Id == 1).RemoveDataCache().ExecuteCommand();
//Updateable和Insertable一樣用法
自動刪除快取
SqlSugarClient db = new SqlSugarClient(new ConnectionConfig() {
ConnectionString = Config.ConnectionString,
MoreSettings =new ConnMoreSettings(){
IsAutoRemoveDataCache=true
}
建立db物件
我們需要建立一個MyCache類，你可以用我寫好的也可以用你自已寫的實現快取
ICacheService myCache = new RedisCache("10.1.249.196");//ICacheService
SqlSugarClient db = new SqlSugarClient(new ConnectionConfig()
{
ConnectionString = Config.ConnectionString,
DbType = DbType.SqlServer,
IsAutoCloseConnection = true,
ConfigureExternalServices = new ConfigureExternalServices()
{
DataInfoCacheService = new RedisCache() //RedisCache是繼承ICacheService自已實現的一個類
}
});
我寫好的Cache類可以作為參考
Redis:
https://github.com/sunkaixuan/SqlSugar/blob/dev/Src/Asp.Net/SqlSugar.Extensions.DataCache/RedisCache.cs
.Net自帶Cache:
https://github.com/sunkaixuan/SqlSugar/blob/dev/Src/Asp.Net/SqlSugar.Extensions.DataCache/HttpRuntimeCache.cs
永久開源，原始碼下：
https://github.com/sunkaixuan/SqlSugar
SqlSugar一直在默默進步，得到了一些大型企業的認可，但這只是開始，希望你喜歡。
來源：https://www.cnblogs.com/sunkaixuan/p/9787566.html