the following steps:// 1) use Split to break each row (a string) into an array// of strings,// 2) use Skip to skip the "Student ID" column, and store the// rest of the row in scores.// 3) convert each score in the current row from a string to// an int, and ...
生成SQL语句为:SELECT COUNT_BIG(*) FROM [quote] var q = db.Customers.LongCount(); Sum [/quote] 1. 2. 3. 4. 5. 6. 7. 说明:返回集合中数值类型元素之和,集合应为INT类型集合;不延迟。生成SQL语句为:SELECT SUM(…) FROM 1.简单形式: 得到所有订单的总运费: [quote] var q = db.Orders....
the following steps:// 1) use Split to break each row (a string) into an array// of strings,// 2) use Skip to skip the "Student ID" column, and store the// rest of the row in scores.// 3) convert each score in the current row from a string to// an int, and...
varq =fromcindb.Customerswherec.City =="London"selectc.ContactName; 6.shaped类型形式: 说明:其select操作使用了匿名对象,而这个匿名对象中,其属性也是个匿名对象。 varq =fromcindb.Customersselectnew{c.CustomerID,CompanyInfo =new{c.CompanyName, c.City, c.Country}, ContactInfo =new{c.ContactName...
the following steps:// 1) use Split to break each row (a string) into an array// of strings,// 2) use Skip to skip the "Student ID" column, and store the// rest of the row in scores.// 3) convert each score in the current row from a string to// an int, ...
Average DataGridView1.DataSource = averageCustomersByCity 'Another way to grab the count and sum londonCustomerCount = (From cust in db.Customers Where cust.City = "London").Count() venezuelaTotalOrders = (From cust in db.Customers Where cust.Country = "Venezuela" Select cust.Orders).Sum()...
the following steps:// 1) use Split to break each row (a string) into an array// of strings,// 2) use Skip to skip the "Student ID" column, and store the// rest of the row in scores.// 3) convert each score in the current row from a string to// an int, a...
Select/Distinct操作符 适用场景: 查询。 说明:和SQL命令中的select作用相似但位置不同,查询表达式中的select及所接子句是放在表达式最后并把子句中的变量也就是结果返回回来;延迟。 Select/Distinct操作包括9种形式,分别为简单用法、匿名类型形式、条件形式、指定类型形式、筛选形式、整形类型形式、嵌套类型形式、本地方...
(cust.Orders.Count)OrderByAverage DataGridView1.DataSource = averageCustomersByCity'Another way to grab the count and sumlondonCustomerCount = (Fromcustindb.CustomersWherecust.City ="London").Count() venezuelaTotalOrders = (Fromcustindb.CustomersWherecust.Country ="Venezuela"Selectcust.Orders).Sum...
介绍性的语言集成查询 (LINQ) 文档中的大多数查询是使用 LINQ 声明性查询语法编写的。 C# 编译器将查询语法转换为方法调用。 这些方法调用实现标准查询运算符,并具有Where、Select、GroupBy、Join、Max和Average等名称。 可以使用方法语法(而不查询语法)来直接调用它们。