ServiceStack.OrmLite 6 学习笔记查

查

根据id

var result = db.SingleById<Poco>(1);

根据字段

var customer = db.Single<Customer>(new { customer.Email });

动态结果

db.Select<List<object>>(db.From<Poco>().Select("COUNT(*), MIN(Id), MAX(Id)"))[0];

//  List<object>:[ 10, 1,  10]

同上

db.Select<Dictionary<string,object>>(db.From<Poco>().Select("COUNT(*) Total, MIN(Id) MinId, MAX(Id) MaxId"))[0]

单行

db.Single<List<object>>(db.From<Poco>().Select("COUNT(*) Total, MIN(Id) MinId, MAX(Id) MaxId"))

硬来  首行首列

object result = db.Scalar<object>(db.From<Poco>().Select(x => x.Id));

in操作 Order表的CustomerId等于Customer表记录（Country等于USA）的id

sql：select * from Order where CustomerId in ( select id from Customer where Country = "USA" )

var usaCustomerIds = db.From<Customer>(c => c.Country == "USA").Select(c => c.Id);

var usaCustomerOrders = db.Select(db.From<Order>()

.Where(q => Sql.In(q.CustomerId, usaCustomerIds)));

db.Select<Author>(q => q.Birthday >= new DateTime(agesAgo, 1, 1)

                && q.Birthday <= new DateTime(agesAgo, 12, 31));

In

db.Select(q => Sql.In(q.City, "London", "Madrid", "Berlin"));

sql: WHERE "JobCity" In ('London', 'Madrid', 'Berlin')

like a开头

db.Select(q => q.Name.StartsWith("A"));

WHERE upper("Name") like 'A%'

like GARZON结尾

db.Select(q => q.Name.EndsWith("garzon"));

WHERE upper("Name") like '%GARZON'

like 包含

db.Select(q => q.Name.Contains("Benedict"));

WHERE upper("Name") like '%BENEDICT%'

and

db.Select(q => q.Rate == 10 && q.City == "Mexico");

WHERE (("Rate" = 10) AND ("JobCity" = 'Mexico'))

最大

int maxAgeUnder50 = db.Scalar<Person, int>(x => Sql.Max(x.Age), x => x.Age < 50);

SELECT Max("Age") FROM "Person" WHERE ("Age" < 50)

count 汇总

int peopleOver40 = db.Scalar( db.From().Select(Sql.Count("*")).Where(q => q.Age > 40));

int peopleUnder50 = db.Count(x => x.Age < 50);

不通过id Single会加top 1

Person personByAge = db.Single(x => x.Age == 42);

是否存在

bool has42YearOlds = db.Exists(new { Age = 42 });

返回固定字段

List results = db.Column(db.From().Select(x => x.LastName).Where(q => q.Age == 27));

SELECT "LastName" FROM "Person" WHERE ("Age" = 27)

---

对结果去重

HashSet<int> results = db.ColumnDistinct<int>(db.From<Person>().Select(x => x.Age) .Where(q => q.Age < 50));

SELECT "Age" FROM "Person" WHERE ("Age" < 50)

 字典结果

 Dictionary<int,string> results = db.Dictionary<int, string>( db.From<Person>().Select(x => new { x.Id, x.LastName }).Where(x => x.Age < 50));

SELECT "Id","LastName" FROM "Person" WHERE ("Age" < 50)

复杂的字典

Dictionary<int, List> results = db.Lookup<int, string>(db.From().Select(x => new { x.Age, x.LastName }).Where(q => q.Age < 50));

  SELECT "Age","LastName" FROM "Person" WHERE ("Age" < 50)

   SelectFmt 参数格式化

   var tracks = db.SelectFmt<Track>("Artist = {0} AND Album = {1}", "Nirvana", "Heart Shaped Box");

   等同于

   var tracks = db.SelectFmt<Track>("SELECT * FROM track WHERE Artist={0} AND Album={1}","Nirvana",  "Heart Shaped Box");

    多条记录

    List<Track> tracks = db.Select<Track>()

单条记录

Track track = db.Single(q => q.RefId == refId)

字典前2列

Dictionary<int, string> trackIdNamesMap = db.Dictionary<int, string>( "select Id, Name from Track")

Lookup 字典前2列返回的是Dictionary < K, List < V > >

Dictionary<int, List> albumTrackNames = db.Lookup<int, string>( "select AlbumId, Name from Track")

返回首列

List trackNames = db.Column("select Name from Track")

HashSet首列值去重

HashSet uniqueTrackNames = db.ColumnDistinct("select Name from Track")

Scalar返回单行单列

var trackCount = db.Scalar("select count(*) from Track")

默认为and条件

var track3 = db.Where(new { AlbumName = "Throwing Copper", TrackNo = 3 })

这种方式被用烂了大街属性对应参数名

var track3 = db.Select(

"select * from Track Where AlbumName = @album and TrackNo = @trackNo", new { album = "Throwing Copper", trackNo = 3 })

通过id 返回强类型

var track = db.SingleById(1); id等于1的一条

var tracks = db.SelectByIds(new[]{ 1,2,3 }); id等于 1 2 3的三条

延迟加载 SelectLazy这种以Lazy结尾

var lazyQuery = db.SelectLazy("Age > @age", new { age = 40 });

// Iterate over a lazy sequence

foreach (var person in lazyQuery) {

//...

}

其他类同如下

var topVIPs = db.WhereLazy(new { Age = 27 }).Where(p => IsVip(p)).Take(5)

var topVIPs = db.SelectLazyFmt("Age > {0}", 40).Where(p => IsVip(p)).Take(5)