mysql存储过程group_concat为游标中的选择返回null

Question

I have a stored procedure where I'm looping through results in a cursor. The issue I'm having is the license_attributes value is always null when it shouldn't be. If I execute the select statement outside the stored procedure, or as a debug execute the select statement outside the cursor in the stored procedure, I get the results I'm expecting (not null)

This is the part of the select that is always returning null in the cursor:

        (SELECT 
            CONCAT('{""',sf.Asset_Attribute__c.Type__c,'"": {',GROUP_CONCAT(
            '""',sf.Asset_Attribute__c.Key__c,'"":""',LOWER(sf.Asset_Attribute__c.Value__c),'""'
            ),'}}')
            FROM 
                sf.Asset_Attribute__c 
            WHERE 
                sf.Asset_Attribute__c.Asset__c = license_id
            GROUP BY sf.Asset_Attribute__c.Asset__c) AS `license_attributes`

Here is the section of the stored proc:

    GETCLOUDACCOUNTS:BEGIN

    DECLARE no_more_cloud_accounts_records boolean DEFAULT FALSE;

    DECLARE company VARCHAR(255) DEFAULT null;
    DECLARE license_status VARCHAR(50) DEFAULT null;
    DECLARE license_id VARCHAR(18) DEFAULT null;
    DECLARE cloud_owner_email VARCHAR(255) DEFAULT null;
    DECLARE entitlement_plan VARCHAR(255) DEFAULT null;
    DECLARE role VARCHAR(500) DEFAULT null;
    DECLARE is_trial BOOLEAN DEFAULT false;
    DECLARE license_attributes VARCHAR(2000) DEFAULT null;
    DECLARE zuora_account_id VARCHAR(100) DEFAULT '';
    DECLARE zuora_account_number VARCHAR(50) DEFAULT null;
    DECLARE zuora_account_status VARCHAR(50) DEFAULT null;
    DECLARE zuora_account_last_invoice_date DATETIME DEFAULT null;
    DECLARE has_active_subscriptions BOOLEAN DEFAULT false;

    DECLARE cloud_accounts_cursor CURSOR FOR 
        SELECT
            (SELECT `sf`.`Contact`.`CompanyName__c` FROM `sf`.`Contact` WHERE `sf`.`Asset`.`ContactId`=`sf`.`Contact`.`Id`) AS `company`,
            `sf`.`License_Key_Association__c`.`License_Key_Status__c` AS `license_status`,
            `sf`.`License_Key_Association__c`.`License_Key__c` AS `license_id`,
            `sf`.`Asset`.`ContactEmail__c` AS `cloud_owner_email`,
            (SELECT `sf`.`Contact`.`CloudEntitlementPlan__c` FROM `sf`.`Contact` WHERE `sf`.`Asset`.`ContactId`=`sf`.`Contact`.`Id`) AS `entitlement_plan`,
            `sf`.`License_Key_Association__c`.`Role__c` AS `role`,
            IF( (SELECT `sf`.`Product2`.`IsCommercial__c` FROM `sf`.`Product2` WHERE `sf`.`Product2`.`Id`=`sf`.`Asset`.`Product2Id`) = 0,true,false ) AS `is_trial`,
            (SELECT 
                CONCAT('{""',sf.Asset_Attribute__c.Type__c,'"": {',GROUP_CONCAT(
                '""',sf.Asset_Attribute__c.Key__c,'"":""',LOWER(sf.Asset_Attribute__c.Value__c),'""'
                ),'}}')
                FROM 
                    sf.Asset_Attribute__c 
                WHERE 
                    sf.Asset_Attribute__c.Asset__c = license_id
                GROUP BY sf.Asset_Attribute__c.Asset__c) AS `license_attributes`
        FROM
            `sf`.`License_Key_Association__c`
        LEFT JOIN `sf`.`Asset`
            ON `sf`.`License_Key_Association__c`.`License_Key__c` = `sf`.`Asset`.`Id` 
        JOIN `sf`.`Contact`
            ON `sf`.`Contact`.`Id` = `sf`.`License_Key_Association__c`.`Contact__c`
        WHERE
            `sf`.`Contact`.`ExternalID__c`='someexternalidhere';

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET no_more_cloud_accounts_records = true;
        SELECT
            (SELECT `sf`.`Contact`.`CompanyName__c` FROM `sf`.`Contact` WHERE `sf`.`Asset`.`ContactId`=`sf`.`Contact`.`Id`) AS `company`,
            `sf`.`License_Key_Association__c`.`License_Key_Status__c` AS `license_status`,
            `sf`.`License_Key_Association__c`.`License_Key__c` AS `license_id`,
            `sf`.`Asset`.`ContactEmail__c` AS `cloud_owner_email`,
            (SELECT `sf`.`Contact`.`CloudEntitlementPlan__c` FROM `sf`.`Contact` WHERE `sf`.`Asset`.`ContactId`=`sf`.`Contact`.`Id`) AS `entitlement_plan`,
            `sf`.`License_Key_Association__c`.`Role__c` AS `role`,
            IF( (SELECT `sf`.`Product2`.`IsCommercial__c` FROM `sf`.`Product2` WHERE `sf`.`Product2`.`Id`=`sf`.`Asset`.`Product2Id`) = 0,true,false ) AS `is_trial`,
            (SELECT 
                CONCAT('{""',sf.Asset_Attribute__c.Type__c,'"": {',GROUP_CONCAT(
                '""',sf.Asset_Attribute__c.Key__c,'"":""',LOWER(sf.Asset_Attribute__c.Value__c),'""'
                ),'}}')
                FROM 
                    sf.Asset_Attribute__c 
                WHERE 
                    sf.Asset_Attribute__c.Asset__c = license_id
                GROUP BY sf.Asset_Attribute__c.Asset__c) AS `license_attributes`
        FROM
            `sf`.`License_Key_Association__c`
        LEFT JOIN `sf`.`Asset`
            ON `sf`.`License_Key_Association__c`.`License_Key__c` = `sf`.`Asset`.`Id` 
        JOIN `sf`.`Contact`
            ON `sf`.`Contact`.`Id` = `sf`.`License_Key_Association__c`.`Contact__c`
        WHERE
            `sf`.`Contact`.`ExternalID__c`=@p_externalId;

    OPEN cloud_accounts_cursor;
    CLOUDACCOUNTSLOOP: loop

        fetch cloud_accounts_cursor into company, license_status, license_id, cloud_owner_email, entitlement_plan, role, is_trial, license_attributes;

        IF is_trial = true THEN
            SET has_active_subscriptions = true;
        END IF;

        SET zuora_account_id = `z`.`getZAccountId`(cloud_owner_email);

        IF zuora_account_id IS NOT NULL THEN
            SELECT `accountNumber`,`status`,`lastInvoiceDate` INTO zuora_account_number,zuora_account_status,zuora_account_last_invoice_date FROM zuora.Account WHERE id=zuora_account_id;

            IF has_active_subscriptions = false THEN
                SET has_active_subscriptions = (SELECT IF((SELECT COUNT(*) FROM `z`.`RatePlan`
                    RIGHT JOIN `z`.`ProductRatePlan` ON `z`.`RatePlan`.`productRatePlanId` = `z`.`ProductRatePlan`.`id`
                    LEFT JOIN `z`.`Subscription` ON `z`.`RatePlan`.`subscriptionId` = `z`.`Subscription`.`id`
                    WHERE
                    `z`.`ProductRatePlan`.`wowzaRatePlanCode__c` IN ( (SELECT `code` FROM `z`.`zCloudRatePlanCodes`) )
                    AND `z`.`Subscription`.`status` = 'Active'
                    AND `z`.`Subscription`.`accountId` = zuora_account_id ) > 0, true, false));
            END IF;
        END IF;

        REPLACE INTO `sf`.`zCloudAccounts` (`user_email`,`company`,`license_status`,`license_id`,`cloud_owner_email`,`entitlement_plan`,`role`,`is_trial`,`attributes`,`zuora_account_id`,`zuora_account_number`,`zuora_account_status`,`zuora_account_last_invoice_date`,`has_active_subscriptions`) VALUES(@p_userEmail,company,license_status,license_id,cloud_owner_email,entitlement_plan,role,is_trial,license_attributes,zuora_account_id,zuora_account_number,zuora_account_status,zuora_account_last_invoice_date,has_active_subscriptions);

        IF no_more_cloud_accounts_records THEN
            CLOSE cloud_accounts_cursor;
            LEAVE CLOUDACCOUNTSLOOP;
        end if;

    END LOOP CLOUDACCOUNTSLOOP;

END GETCLOUDACCOUNTS;

If I execute the full select stateout outside of GETCLOUDACCOUNTS block, I get the results I expect:

company, license_status, license_id, cloud_owner_email, entitlement_plan, role, is_trial, license_attributes
Test Company, Active, 02iq0000000jKgMAAU, myemail@email.com, Standard, Owner, 0, {""cloud"": {""cloud_num_247_t_streams"":""0"",""cloud_num_247_p_streams"":""0""}}
Test Company, Active, 02iq0000000xlBBAAY, otheremail@email.com, Standard, Admin;wcl_admin;wcl_support, 0, {""cloud"": {""cloud_num_247_t_streams"":""1"",""cloud_num_247_p_streams"":""1"",""test_attribute"":""true"",""api_access"":""true""}}

But the results inside the block show license_attributes as null:

company, license_status, license_id, cloud_owner_email, entitlement_plan, role, is_trial, license_attributes
Test Company, Active, 02iq0000000jKgMAAU, myemail@email.com, Standard, Owner, 0, null
Test Company, Active, 02iq0000000xlBBAAY, otheremail@email.com, Standard, Admin;wcl_admin;wcl_support, 0, null

Any help is greatly appreciated!

Answer 1

I suspect the issue is related to the procedure variable license_id .

The correlated subselect in the SELECT list includes

 WHERE sf.Asset_Attribute__c.Asset__c = license_id
                                        ^^^^^^^^^^

Local variables take precedence over column references. Since license_id is declared as a variable within the code block,

 DECLARE license_id VARCHAR(18) DEFAULT null;

the reference to license_id in the SELECT statement is a reference to that procedure variable.

Outside the code block, there likely is not a local variable named license_id . So that same SQL SELECT statement, that reference to license_id is not a reference to a variable, but a reference to a column.

I haven't traced through all of the logic, or the contents of license_id variable. But I suspect that explains the difference in the behavior observed with the statement, executed inside the code block vs outside the block.

Answer 2

You can COALESCE to take care of NULL values in your GROUP_CONCAT

COALESCE(`YourColumnName`,'')

You can also use a significantly different string to show you where the NULL value is coming from, so that you can then fix the query.

COALESCE(`YourColumnName`,'**UNEXPECTED NULL**')