Azure Stream 分析 - SQL

Question

.json is Input to Azure Stream Analytics. One of the column ( body ) is in BASE64 format. I can covert this in SQL Server Management Studio with following query.

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

But when trying to execute in Stream Analytics Query is warning with Error saying:

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

Query:

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

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

This error message indicates that the ASA runtime mistakenly assumes that you want to execute user defined function in ASA SQL.The syntax is udf.XXX() .

ASA SQL still has many different behaviors from normal SQL, actually.The base64 convert method in your question is not supported in ASA SQL.

You could define user defined function is ASA so that you could implement same requirement.For example, please refer to below part from this document .

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;