Azure流分析-SQL

Question

.json是Azure流分析的输入。列（body）之一为BASE64格式。我可以使用以下查询在SQL Server Management Studio中对此进行隐藏。

declare @v varchar(1000) = 'cm9sZToxIHByb2R1Y2VyOjEyIHRpbWVzdGFtcDoxNDY4NjQwMjIyNTcxMDAwIGxhdGxuZ3tsYXRpdHVkZV9lNzo0MTY5ODkzOTQgbG9uZ2l0dWRlX2U3Oi03Mzg5NjYyMTB9IHJhZGl1czoxOTc2NA=='
    SELECT 
    CAST(
        CAST('' AS XML).value('xs:base64Binary(sql:column("BASE64_COLUMN"))', 'VARBINARY(MAX)')
        AS VARCHAR(MAX)
    )   AS Result
    FROM
    (
        SELECT @v AS BASE64_COLUMN
    ) A

但是在流分析中尝试执行查询时会出现警告，错误提示：

Function 'value' is either not supported or not usable in this context. User defined function calls must start with "udf."

查询：

SELECT 
    CAST(
        CAST('' AS XML).value('xs:base64Binary(sql:column("BASE64_COLUMN"))', 'VARBINARY(MAX)')
        AS VARCHAR(MAX)
    )   AS Result
    INTO
    [IOTPowerBIStreaming]
    FROM
    (
        SELECT body AS BASE64_COLUMN  FROM  [IOTInput]
    ) A

Answer 1

此功能'值'在此不被支持或不可用上下文。用户定义的函数调用必须以“ udf”开头。

此错误消息表示ASA运行时错误地假定您要在ASA SQL中执行user defined function。语法为udf.XXX()。

实际上，ASA SQL与普通SQL仍有许多不同的行为。您的问题中的base64 convert方法在ASA SQL中不受支持。

您可以将用户定义的功能定义为ASA，以便可以实现相同的要求。例如，请参考此document的以下部分。

var Base64={_keyStr:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
encode:function(e){var t="";var n,r,i,s,o,u,a;var f=0;e=Base64._utf8_encode(e);while(f<e.length){n=e.charCodeAt(f++);r=e.charCodeAt(f++);i=e.charCodeAt(f++);s=n>>2;o=(n&3)<<4|r>>4;u=(r&15)<<2|i>>6;a=i&63;if(isNaN(r)){u=a=64}else if(isNaN(i)){a=64}t=t+this._keyStr.charAt(s)+this._keyStr.charAt(o)+this._keyStr.charAt(u)+this._keyStr.charAt(a)}return t},
decode:function(e){var t="";var n,r,i;var s,o,u,a;var f=0;e=e.replace(/++[++^A-Za-z0-9+/=]/g,"");while(f<e.length){s=this._keyStr.indexOf(e.charAt(f++));o=this._keyStr.indexOf(e.charAt(f++));u=this._keyStr.indexOf(e.charAt(f++));a=this._keyStr.indexOf(e.charAt(f++));n=s<<2|o>>4;r=(o&15)<<4|u>>2;i=(u&3)<<6|a;t=t+String.fromCharCode(n);if(u!=64){t=t+String.fromCharCode(r)}if(a!=64){t=t+String.fromCharCode(i)}}t=Base64._utf8_decode(t);return t},
_utf8_encode:function(e){e=e.replace(/\r\n/g,"n");var t="";for(var n=0;n<e.length;n++){var r=e.charCodeAt(n);if(r<128){t+=String.fromCharCode(r)}else if(r>127&&r<2048){t+=String.fromCharCode(r>>6|192);t+=String.fromCharCode(r&63|128)}else{t+=String.fromCharCode(r>>12|224);t+=String.fromCharCode(r>>6&63|128);t+=String.fromCharCode(r&63|128)}}return t},
_utf8_decode:function(e){var t="";var n=0;var r=c1=c2=0;while(n<e.length){r=e.charCodeAt(n);if(r<128){t+=String.fromCharCode(r);n++}else if(r>191&&r<224){c2=e.charCodeAt(n+1);t+=String.fromCharCode((r&31)<<6|c2&63);n+=2}else{c2=e.charCodeAt(n+1);c3=e.charCodeAt(n+2);t+=String.fromCharCode((r&15)<<12|(c2&63)<<6|c3&63);n+=3}}return t}};
var encodedString = Base64.encode(input);
return encodedString;