DbFunctions.Left 方法
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用於 LINQ to Entities 查詢時，此方法會叫用標準 EDM 函式 Left 以傳回某字串最左邊指定之數目的字元。
命名空間： System.Data.Entity
組件： EntityFramework (在 EntityFramework.dll 中)
語法
'宣告
<SuppressMessageAttribute("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId := "length")> _
<SuppressMessageAttribute("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId := "stringArgument")> _
<SuppressMessageAttribute("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId := "string")> _
<DbFunctionAttribute("Edm", "Left")> _
Public Shared Function Left ( _
stringArgument As String, _
length As Nullable(Of Long) _
) As String
'用途
Dim stringArgument As String
Dim length As Nullable(Of Long)
Dim returnValue As String
returnValue = DbFunctions.Left(stringArgument, _
length)
[SuppressMessageAttribute("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId = "length")]
[SuppressMessageAttribute("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId = "stringArgument")]
[SuppressMessageAttribute("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "string")]
[DbFunctionAttribute("Edm", "Left")]
public static string Left(
string stringArgument,
Nullable<long> length
)
[SuppressMessageAttribute(L"Microsoft.Usage", L"CA1801:ReviewUnusedParameters", MessageId = L"length")]
[SuppressMessageAttribute(L"Microsoft.Usage", L"CA1801:ReviewUnusedParameters", MessageId = L"stringArgument")]
[SuppressMessageAttribute(L"Microsoft.Naming", L"CA1720:IdentifiersShouldNotContainTypeNames", MessageId = L"string")]
[DbFunctionAttribute(L"Edm", L"Left")]
public:
static String^ Left(
String^ stringArgument,
Nullable<long long> length
)
[<SuppressMessageAttribute("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId = "length")>]
[<SuppressMessageAttribute("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId = "stringArgument")>]
[<SuppressMessageAttribute("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "string")>]
[<DbFunctionAttribute("Edm", "Left")>]
static member Left :
stringArgument:string *
length:Nullable<int64> -> string
public static function Left(
stringArgument : String,
length : Nullable<long>
) : String
參數
- stringArgument
類型：System.String
輸入字串。
- length
類型：System.Nullable<Int64>
要傳回的字元數。
傳回值
類型：System.String
包含從輸入字串左邊算起，長度達指定之字元數的字串。
備註
您不可以直接呼叫此函式。 此函式只能出現在 LINQ to Entities 查詢內。 此函式會轉譯為資料庫中的對應函式。