().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(c => c.Country == "USA").Select(c => c.Id);
var usaCustomerOrders = db.Select(db.From()
.Where(q => Sql.In(q.CustomerId, usaCustomerIds)));
db.Select(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 results = db.ColumnDistinct(db.From().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().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
多条记录
List
单条记录
Track track = db.Single
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
这种方式被用烂了大街 属性对应参数名
var track3 = db.Select
通过id 返回强类型
var track = db.SingleById
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)
浙公网安备 33010602011771号