ServiceStack.OrmLite 6 學習筆記 查

查

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

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

動态結果
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]
           

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

硬來  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表記錄（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開頭

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

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

like GARZON結尾

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 彙總

int peopleOver40 = db.Scalar( db.From

().Select(Sql.Count("*")).Where(q => q.Age > 40));

int peopleUnder50 = db.Count

(x => x.Age < 50);

不通過id Single會加top 1

Person personByAge = db.Single

(x => x.Age == 42);

是否存在

bool has42YearOlds = db.Exists

(new { Age = 42 });

傳回固定字段

List results = db.Column(db.From

().Select(x => x.LastName).Where(q => q.Age == 27));

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

---
對結果去重
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)
           

字典結果
 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)
           

複雜的字典

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 參數格式化
   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");
           

多條記錄
    List<Track> tracks = db.Select<Track>()
           

單條記錄

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 傳回的是Dictionary < K, List < V > >

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

傳回首列

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

HashSet首列值去重

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

Scalar傳回單行單列

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

預設為and條件

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

這種方式被用爛了大街 屬性對應參數名

var track3 = db.Select(

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

通過id 傳回強類型

var track = db.SingleById(1); id等于1的一條

var tracks = db.SelectByIds(new[]{ 1,2,3 }); id等于 1 2 3的三條

延遲加載 SelectLazy這種以Lazy結尾

var lazyQuery = db.SelectLazy

("Age > @age", new { age = 40 });

// Iterate over a lazy sequence

foreach (var person in lazyQuery) {

//...

}

其他類同 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)

作者：

過錯

出處：http://www.cnblogs.com/wang2650/

關于作者：net開發做的久而已。十餘年時光虛度！

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