DbExpressionBuilder.Case(IEnumerable<DbExpression>, IEnumerable<DbExpression>, DbExpression) 方法

定义

创建一个新的 DbCaseExpressionCreates a new DbCaseExpression.

public:
 static System::Data::Common::CommandTrees::DbCaseExpression ^ Case(System::Collections::Generic::IEnumerable<System::Data::Common::CommandTrees::DbExpression ^> ^ whenExpressions, System::Collections::Generic::IEnumerable<System::Data::Common::CommandTrees::DbExpression ^> ^ thenExpressions, System::Data::Common::CommandTrees::DbExpression ^ elseExpression);
public static System.Data.Common.CommandTrees.DbCaseExpression Case (System.Collections.Generic.IEnumerable<System.Data.Common.CommandTrees.DbExpression> whenExpressions, System.Collections.Generic.IEnumerable<System.Data.Common.CommandTrees.DbExpression> thenExpressions, System.Data.Common.CommandTrees.DbExpression elseExpression);
static member Case : seq<System.Data.Common.CommandTrees.DbExpression> * seq<System.Data.Common.CommandTrees.DbExpression> * System.Data.Common.CommandTrees.DbExpression -> System.Data.Common.CommandTrees.DbCaseExpression
Public Function Case (whenExpressions As IEnumerable(Of DbExpression), thenExpressions As IEnumerable(Of DbExpression), elseExpression As DbExpression) As DbCaseExpression

参数

whenExpressions
IEnumerable<DbExpression>

提供每个 Case 的条件的表达式列表。A list of expressions that provide the conditional for of each case.

thenExpressions
IEnumerable<DbExpression>

提供每个 Case 的结果的表达式列表。A list of expressions that provide the result of each case.

elseExpression
DbExpression

定义没有 Case 匹配时的结果的表达式。An expression that defines the result when no case is matched.

返回

DbCaseExpression

使用指定的案件和默认结果的新 DbCaseExpression。A new DbCaseExpression with the specified cases and default result.

例外

whenExpressionsthenExpressions 为 null 或包含 null,或者 elseExpression 为 null。whenExpressions or thenExpressions is null or contains null, or elseExpression is null.

whenExpressionsthenExpressions 为空,或者 whenExpressions 包含一个带有非布尔结果类型的表达式,或者没有适用于 thenExpressionselseExpression 中的所有表达式的通用结果类型。whenExpressions or thenExpressions is empty or whenExpressions contains an expression with a non-Boolean result type, or no common result type exists for all expressions in thenExpressions and elseExpression.

适用于