System.Data.Common.CommandTrees 命名空间

提供用于生成构成命令树的表达式的类。 Provides classes to build expressions that make up a command tree.

DbAggregate

实现 GroupBy 子句中的聚合所需的基本功能。Implements the basic functionality required by aggregates in a GroupBy clause.

DbAndExpression

表示两个 Boolean 参数的逻辑“与”。Represents the logical AND of two Boolean arguments. 此类不能被继承。This class cannot be inherited.

DbApplyExpression

表示一个应用运算,它是对指定输入集中的每个元素的指定函数调用。Represents an apply operation, which is the invocation of the specified function for each element in the specified input set. 此类不能被继承。This class cannot be inherited.

DbArithmeticExpression

表示应用于数值自变量的算术运算。Represents an arithmetic operation applied to numeric arguments. 加法、减法、乘法、除法、取模和求反都属于算术运算。Addition, subtraction, multiplication, division, modulo, and negation are arithmetic operations. 此类不能被继承。This class cannot be inherited.

DbBinaryExpression

为接受两个表达式操作数的表达式实现所需的基本功能。Implements the basic functionality required by expressions that accept two expression operands.

DbCaseExpression

表示 DbCaseExpressionWhenThenElse 子句。Represents the When, Then, and Else clauses of the DbCaseExpression. 此类不能被继承。This class cannot be inherited.

DbCastExpression

表示单个参数向指定类型的类型转换。Represents the type conversion of a single argument to the specified type. 此类不能被继承。This class cannot be inherited.

DbCommandTree

一个不可变的类,用于实现 Query、Insert、Update、Delete 和函数调用命令目录树类型的基本功能。An immutable class that implements the basic functionality for the Query, Insert, Update, Delete, and function invocation command tree types.

DbComparisonExpression

表示应用于两个自变量的比较运算。Represents a comparison operation applied to two arguments. 相等、大于、大于或等于、小于、小于或等于以及不等都属于比较运算。Equality, greater than, greater than or equal, less than, less than or equal, and inequality are comparison operations. 此类不能被继承。This class cannot be inherited.

DbConstantExpression

表示不同类型的常量(文本)。Represents different kinds of constants (literals). 此类不能被继承。This class cannot be inherited.

DbCrossJoinExpression

表示给定集合自变量之间的无条件联接运算。Represents an unconditional join operation between the given collection arguments. 此类不能被继承。This class cannot be inherited.

DbDeleteCommandTree

表示一项以命令目录树形式表示的单行删除操作。Represents a single row delete operation expressed as a command tree. 此类不能被继承。This class cannot be inherited.

DbDerefExpression

表示基于指定的引用检索实体的表达式。Represents the an expression that retrieves an entity based on the specified reference. 此类不能被继承。This class cannot be inherited.

DbDistinctExpression

从指定的集参数中删除重复的元素。Removes duplicate elements from the specified set argument. 此类不能被继承。This class cannot be inherited.

DbElementExpression

表示指定集自变量到单一实例的转换。Represents the conversion of the specified set argument to a singleton. 此类不能被继承。This class cannot be inherited.

DbEntityRefExpression

表示从基础实体实例提取引用的表达式。Represents an expression that extracts a reference from the underlying entity instance. 此类不能被继承。This class cannot be inherited.

DbExceptExpression

表示左右操作数之间的集减法运算。Represents the set subtraction operation between the left and right operands. 此类不能被继承。This class cannot be inherited.

DbExpression

表示所有表达式的基类型。Represents the base type for all expressions.

DbExpressionBinding

表示到关系表达式(例如 DbFilterExpressionDbProjectExpressionDbJoinExpression)的输入集。Represents an input set to relational expressions such as DbFilterExpression, DbProjectExpression, and DbJoinExpression. 此类不能被继承。This class cannot be inherited.

DbExpressionVisitor

定义不返回结果值的访问者应实现的基本功能。Defines the basic functionality that should be implemented by visitors that do not return a result value.

DbExpressionVisitor<TResultType>

定义返回特定类型结果值的访问者应实现的基本功能。Defines the basic functionality that should be implemented by visitors that return a result value of a specific type.

DbFilterExpression

表示用于筛选输入集的谓词。Represents a predicate applied to filter an input set. 它生成满足该谓词的元素集。This produces the set of elements that satisfy the predicate. 此类不能被继承。This class cannot be inherited.

DbFunctionAggregate

支持标准聚合函数,例如 MIN、MAX、AVG、SUM 等等。Supports standard aggregate functions, such as MIN, MAX, AVG, SUM, and so on. 此类不能被继承。This class cannot be inherited.

DbFunctionCommandTree

表示对数据库函数的调用。Represents the invocation of a database function.

DbFunctionExpression

表示对函数的调用。Represents an invocation of a function. 此类不能被继承。This class cannot be inherited.

DbGroupAggregate

表示构成组的元素的集合。Represents a collection of elements that compose a group.

DbGroupByExpression

表示分组运算。Represents a group by operation. 分组运算是根据指定的键表达式将输入集中的元素分组,后接指定聚合函数的应用。A group by operation is a grouping of the elements in the input set based on the specified key expressions followed by the application of the specified aggregates. 此类不能被继承。This class cannot be inherited.

DbGroupExpressionBinding

定义输入集到 DbGroupByExpression 的绑定。Defines the binding for the input set to a DbGroupByExpression. 此类不能被继承。This class cannot be inherited.

DbInsertCommandTree

表示一项以命令目录树形式表示的单行插入操作。Represents a single row insert operation expressed as a command tree. 此类不能被继承。This class cannot be inherited.

DbIntersectExpression

表示左右操作数之间的交集运算。Represents the set intersection operation between the left and right operands. 此类不能被继承。This class cannot be inherited.

DbIsEmptyExpression

表示一个应用于单集自变量的空集确定。Represents an empty set determination applied to a single set argument. 此类不能被继承。This class cannot be inherited.

DbIsNullExpression

表示应用于单个参数的 null 确定。Represents null determination applied to a single argument. 此类不能被继承。This class cannot be inherited.

DbIsOfExpression

表示单个自变量针对指定类型的类型比较。Represents the type comparison of a single argument against the specified type. 此类不能被继承。This class cannot be inherited.

DbJoinExpression

表示在指定的联接条件下,在给定的集合自变量之间进行的内部、左外部或完全外部联接运算。Represents an inner, left outer, or full outer join operation between the given collection arguments on the specified join condition.

DbLambda

表示一个 Lambda 函数,可以调用此函数以生成 DbLambdaExpressionRepresents a Lambda function that can be invoked to produce a DbLambdaExpression.

DbLambdaExpression

允许对由 DbExpression 对象表示的参数应用 lambda 函数。Allows the application of a lambda function to arguments represented by DbExpression objects.

DbLikeExpression

表示针对指定的模式与可选的转义字符串进行的字符串比较。Represents a string comparison against the specified pattern with an optional escape string. 此类不能被继承。This class cannot be inherited.

DbLimitExpression

表示将自变量集合中的元素数限制为指定的限值。Represents the restriction of the number of elements in the argument collection to the specified limit value.

DbModificationClause

在插入或更新修改操作中指定单个子句。Specifies a single clause in an insert or update modification operation.

DbModificationCommandTree

表示一项以命令目录树形式表示的数据操作语言 (DML) 操作。Represents a data manipulation language (DML) operation expressed as a command tree.

DbNewInstanceExpression

表示给定类型(包括集类型和记录类型)的新实例的构造。Represents the construction of a new instance of a given type, including set and record types. 此类不能被继承。This class cannot be inherited.

DbNotExpression

表示单个 Boolean 参数的逻辑“非”。Represents the logical NOT of a single Boolean argument. 此类不能被继承。This class cannot be inherited.

DbNullExpression

表示对类型化 NULL 文本的引用。Represents a reference to a typed null literal. 此类不能被继承。This class cannot be inherited.

DbOfTypeExpression

表示从给定的集参数中检索属于指定类型的元素。Represents the retrieval of elements of the specified type from the given set argument. 此类不能被继承。This class cannot be inherited.

DbOrExpression

表示两个 Boolean 参数的逻辑“或”。Represents the logical OR of two Boolean arguments. 此类不能被继承。This class cannot be inherited.

DbParameterReferenceExpression

表示对在包含此表达式的命令目录树上声明的参数的引用。Represents a reference to a parameter declared on the command tree that contains this expression. 此类不能被继承。This class cannot be inherited.

DbProjectExpression

表示给定输入集在指定表达式上的投影。Represents the projection of a given input set over the specified expression. 此类不能被继承。This class cannot be inherited.

DbPropertyExpression

提供用于检索实例属性的方法和属性。Provides methods and properties for retrieving an instance property. 此类不能被继承。This class cannot be inherited.

DbQuantifierExpression

表示对指定输入集中的元素执行的指定类型的限定符操作。Represents a quantifier operation of the specified kind over the elements of the specified input set. 此类不能被继承。This class cannot be inherited.

DbQueryCommandTree

表示一项以命令目录树形式表示的查询操作。Represents a query operation expressed as a command tree. 此类不能被继承。This class cannot be inherited.

DbRefExpression

表示对实体集中的特定实例的强类型引用。Represents a strongly typed reference to a specific instance within an entity set. 此类不能被继承。This class cannot be inherited.

DbRefKeyExpression

表示从基础引用值中检索键值(以其结构化形式)。Represents the retrieval of the key value (in its structural form) from the underlying reference value. 此类不能被继承。This class cannot be inherited.

DbRelationshipNavigationExpression

表示关系的导航。Represents the navigation of a relationship. 此类不能被继承。This class cannot be inherited.

DbScanExpression

表示一项对 Target 属性指示的实体集或关系集进行扫描的操作。Represents a scan over an entity set or relationship set, as indicated by the Target property. 此类不能被继承。This class cannot be inherited.

DbSetClause

指定用于设置属性值的修改操作中的子句。Specifies the clause in a modification operation that sets the value of a property. 此类不能被继承。This class cannot be inherited.

DbSkipExpression

跳过指定数量的输入集元素。Skips a specified number of elements in the input set. 只有在输入集合已按排序键指定的顺序进行排序之后,才能使用 DbSkipExpressionDbSkipExpression can only be used after the input collection has been sorted as specified by the sort keys.

DbSortClause

指定可在 DbSortExpression 中用作排序顺序的一部分的排序关键字。Specifies a sort key that can be used as part of the sort order in a DbSortExpression. 此类不能被继承。This class cannot be inherited.

DbSortExpression

表示一项基于给定的排序关键字应用于指定输入集中的元素的排序操作。Represents a sort operation applied to the elements of the specified input set based on the given sort keys. 此类不能被继承。This class cannot be inherited.

DbTreatExpression

表示一项应用于多态自变量的类型转换操作。Represents a type conversion operation applied to a polymorphic argument. 此类不能被继承。This class cannot be inherited.

DbUnaryExpression

为接受单个表达式参数的表达式实现所需的基本功能。Implements the basic functionality required by expressions that accept a single expression argument.

DbUnionAllExpression

表示左右操作数之间的 set 联合(不移除重复项)运算。Represents the set union (without duplicate removal) operation between the left and right operands. 此类不能被继承。This class cannot be inherited.

DbUpdateCommandTree

表示一项以命令目录树形式表示的单行更行操作。Represents a single-row update operation expressed as a command tree. 此类不能被继承。This class cannot be inherited.

DbVariableReferenceExpression

表示对当前处于范围内的某个变量的引用。Represents a reference to a variable that is currently in scope. 此类不能被继承。This class cannot be inherited.

DefaultExpressionVisitor

从给定的根表达式访问表达式树的每个元素。Visits each element of an expression tree from a given root expression. 如果任何元素更改,则树重新生成回根目录,且返回新的根表达式;否则,返回原始根表达式。If any element changes, the tree is rebuilt back to the root and the new root expression is returned; otherwise the original root expression is returned.

枚举

DbExpressionKind

包含每个表达式类用来表示它所代表的运算的值。Contains values that each expression class uses to denote the operation it represents. 可以检索 ExpressionKindDbExpression 属性来确定该表达式所代表的运算。The ExpressionKind property of an DbExpression can be retrieved to determine which operation that expression represents.

注解

命令树是查询的对象模型表示形式,可用于表示在 ADO.NET Entity Data Model (EDM) 和存储元数据中查询、更新、插入及删除命令。A command trees is an object model representation of a query that can be used to represent query, update, insert, and delete commands in the ADO.NET Entity Data Model (EDM) and storage metadata.