SQL Azure-创建外部数据源：位置作为参数？

Question

我正在尝试创建一个SQL存储过程，该过程将创建一个外部数据源。 该位置将是传递到过程中的参数（例如，天青存储帐户容器）。 我无法接受Location变量（如下面的代码片段所示）。

DECLARE @Location varchar(max)
SET @Location = 'https://somestorageaccount.blob.core.windows.net/uploads'

PRINT @Location
--DROP EXTERNAL DATA SOURCE uploads

CREATE EXTERNAL DATA SOURCE uploads
WITH
(
    TYPE = BLOB_STORAGE,
    LOCATION = @Location,
    CREDENTIAL = azurecred
);

错误消息为：

Msg 102, Level 15, State 1, Line 11
Incorrect syntax near '@Location'.

如果带单引号的网址替换了变量，则此方法有效。 即

CREATE EXTERNAL DATA SOURCE uploads
WITH
(
    TYPE = BLOB_STORAGE,
    LOCATION = 'https://somestorageaccount.blob.core.windows.net/uploads'
    CREDENTIAL = azurecred
);

经过试验，我无法使它正常工作。 可能吗？

Answer 1

您不能在DDL语句中使用变量。 尝试使用动态SQL-形成DDL的字符串，并使用sp_executesql存储过程执行它

ALTER PROCEDURE CETFromNewLocation    AS

BEGIN

DECLARE @location varchar(100)

SET @location = 'data/2015/2015831'

DECLARE @CreateExternalTableString varchar(100)

SET @CreateExternalTableString = 
                                    'Create External TABLE stg_tbl (
                                                  [DateId] int NULL
                                    )
                                    WITH (LOCATION = ' + @location + ',                                      
                                             DATA_SOURCE = my_external_source,
                                             FILE_FORMAT = my_external_file_format,
                                             REJECT_TYPE = VALUE,
                                             REJECT_VALUE = 0
                                    )'

EXEC sp_executesql @CreateExternalTableString

END