CREATE TABLE `test_mad` (
  `homeSiteId` int(10),
  `homeSiteLogo` varchar(255) DEFAULT NULL,
  `userid` int(11) NOT NULL DEFAULT '0',
  `status` int(1) DEFAULT NULL COMMENT '0-Reject,1-Approve,2-Pending,3-disable,4-Discharge,6-Rx Universe,7-virtual user,8-Deleted',
  `firstname` varchar(100) DEFAULT NULL,
  `lastname` varchar(100) DEFAULT NULL,
  `avatar` varchar(200) DEFAULT NULL,
  `displayname` varchar(100) NOT NULL,
  `username` varchar(100) DEFAULT NULL COMMENT 'this is used to save the email address for communication purposes',
  `mobile` varchar(20) DEFAULT NULL,
  `countryCode` varchar(50) DEFAULT NULL,
  `grp` varchar(25) NOT NULL,
  `tenantid` int(10) NOT NULL DEFAULT '0',
  `enable_sms_notifications` int(1) DEFAULT NULL,
  `tenant_name` varchar(100),
  `tenantConfigData` mediumtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin,
  `password` varchar(100) DEFAULT NULL,
  `organization_master_id` int(11) DEFAULT NULL,
  `enable_email_notifications` int(1) DEFAULT NULL,
  `tenantNotificationLanguage` mediumtext,
  `site_user_id` bigint(11) DEFAULT NULL,
  `homeSiteConfigData` mediumtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin,
  `homeSiteNotificationLanguage` mediumtext,
  `siteId` int(10) DEFAULT NULL,
  `siteName` varchar(100),
  `siteCount` bigint(21) NOT NULL DEFAULT '0',
  `siteLogo` varchar(255) DEFAULT NULL,
  `siteConfigData` mediumtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin,
  `siteNotificationLanguage` mediumtext,
  `languageConfig` longtext,
  `source_category_id` varchar(9) NOT NULL DEFAULT '',
  `content` json DEFAULT NULL,
  `emailSubject` json DEFAULT NULL,
  `salutation` varchar(500) DEFAULT NULL,
  `emailClosing` varchar(500) DEFAULT NULL,
  `notificationType` bigint(11) DEFAULT NULL,
  `id` bigint(11) DEFAULT NULL,
  `languageId` bigint(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

----******************** Insert the test data 
INSERT INTO `` (`homeSiteId`,`homeSiteLogo`,`userid`,`status`,`firstname`,`lastname`,`avatar`,`displayname`,`username`,`mobile`,`countryCode`,`grp`,`tenantid`,`enable_sms_notifications`,`tenant_name`,`tenantConfigData`,`password`,`organization_master_id`,`enable_email_notifications`,`tenantNotificationLanguage`,`site_user_id`,`homeSiteConfigData`,`homeSiteNotificationLanguage`,`siteId`,`siteName`,`siteCount`,`siteLogo`,`siteConfigData`,`siteNotificationLanguage`,`languageConfig`,`source_category_id`,`content`,`emailSubject`,`salutation`,`emailClosing`,`notificationType`,`id`,`languageId`) VALUES (NULL,NULL,1007,1,'James','Antony','1665475667.jpg','James Antony','user2@citrusdev.com','0','+91','1',1,0,'Citus QA Regression Branch 1','[{\"config_key\": \"app_name\", \"config_value\": \"Test Citus\"},{\"config_key\": \"app_short_link\", \"config_value\": \"https://chb1z-alternate.app.link/9zjnu\"},{\"config_key\": \"branded_appless_url\", \"config_value\": \"https://mobile.citushealth.com\"},{\"config_key\": \"enable_multisite\", \"config_value\": \"0\"},{\"config_key\": \"enable_support_widget_branding\", \"config_value\": \"1\"},{\"config_key\": \"SMTP_domain\", \"config_value\": \"tx.npspharmacy.com\"},{\"config_key\": \"support_widget_from_email\", \"config_value\": \"no-reply@tx.npspharmacy.com\"}]','d27d320c27c3033b7883347d8beca317',20,1,NULL,1007,NULL,NULL,1,'Citus QA Regression Branch 1',1,NULL,'[{\"config_key\": \"app_short_link\", \"config_value\": \"\"},{\"config_key\": \"enable_support_widget_branding\", \"config_value\": \"\"},{\"config_key\": \"support_widget_from_email\", \"config_value\": \"\"},{\"config_key\": \"app_name\", \"config_value\": \"\"},{\"config_key\": \"SMTP_domain\", \"config_value\": \"\"},{\"config_key\": \"notification_language\", \"config_value\": \"es\"}]','es','es','10002_002','{\"INAPP\": \"[Recordatorio] Usted tiene un nuevo formulario para ser completado\", \"Appless\": \"\"}','{}','','',1,93,2);
INSERT INTO `` (`homeSiteId`,`homeSiteLogo`,`userid`,`status`,`firstname`,`lastname`,`avatar`,`displayname`,`username`,`mobile`,`countryCode`,`grp`,`tenantid`,`enable_sms_notifications`,`tenant_name`,`tenantConfigData`,`password`,`organization_master_id`,`enable_email_notifications`,`tenantNotificationLanguage`,`site_user_id`,`homeSiteConfigData`,`homeSiteNotificationLanguage`,`siteId`,`siteName`,`siteCount`,`siteLogo`,`siteConfigData`,`siteNotificationLanguage`,`languageConfig`,`source_category_id`,`content`,`emailSubject`,`salutation`,`emailClosing`,`notificationType`,`id`,`languageId`) VALUES (NULL,NULL,1007,1,'James','Antony','1665475667.jpg','James Antony','user2@citrusdev.com','0','+91','1',1,0,'Citus QA Regression Branch 1','[{\"config_key\": \"app_name\", \"config_value\": \"Test Citus\"},{\"config_key\": \"app_short_link\", \"config_value\": \"https://chb1z-alternate.app.link/9zjnu\"},{\"config_key\": \"branded_appless_url\", \"config_value\": \"https://mobile.citushealth.com\"},{\"config_key\": \"enable_multisite\", \"config_value\": \"0\"},{\"config_key\": \"enable_support_widget_branding\", \"config_value\": \"1\"},{\"config_key\": \"SMTP_domain\", \"config_value\": \"tx.npspharmacy.com\"},{\"config_key\": \"support_widget_from_email\", \"config_value\": \"no-reply@tx.npspharmacy.com\"}]','d27d320c27c3033b7883347d8beca317',20,1,NULL,1007,NULL,NULL,1,'Citus QA Regression Branch 1',1,NULL,'[{\"config_key\": \"app_short_link\", \"config_value\": \"\"},{\"config_key\": \"enable_support_widget_branding\", \"config_value\": \"\"},{\"config_key\": \"support_widget_from_email\", \"config_value\": \"\"},{\"config_key\": \"app_name\", \"config_value\": \"\"},{\"config_key\": \"SMTP_domain\", \"config_value\": \"\"},{\"config_key\": \"notification_language\", \"config_value\": \"es\"}]','es','es','10002_002','{\"INAPP\": \"le han enviado un nuevo formulario de {{site/tenant}}. Presione para leerlo: {{INAPP_Short_Link}}. Responda HELP para obtener información adicional o STOP para cancelar el recibo de mensajes adicionales.\", \"Appless\": \"le han enviado un formulario de {{site/tenant}}. Presione para completar: {{Appless_Short_Link}} Responda HELP para obtener información adicional o STOP para cancelar el recibo de mensajes adicionales.\"}','{}','Hola {{displayName}}','',2,94,2);
INSERT INTO `` (`homeSiteId`,`homeSiteLogo`,`userid`,`status`,`firstname`,`lastname`,`avatar`,`displayname`,`username`,`mobile`,`countryCode`,`grp`,`tenantid`,`enable_sms_notifications`,`tenant_name`,`tenantConfigData`,`password`,`organization_master_id`,`enable_email_notifications`,`tenantNotificationLanguage`,`site_user_id`,`homeSiteConfigData`,`homeSiteNotificationLanguage`,`siteId`,`siteName`,`siteCount`,`siteLogo`,`siteConfigData`,`siteNotificationLanguage`,`languageConfig`,`source_category_id`,`content`,`emailSubject`,`salutation`,`emailClosing`,`notificationType`,`id`,`languageId`) VALUES (NULL,NULL,1007,1,'James','Antony','1665475667.jpg','James Antony','user2@citrusdev.com','0','+91','1',1,0,'Citus QA Regression Branch 1','[{\"config_key\": \"app_name\", \"config_value\": \"Test Citus\"},{\"config_key\": \"app_short_link\", \"config_value\": \"https://chb1z-alternate.app.link/9zjnu\"},{\"config_key\": \"branded_appless_url\", \"config_value\": \"https://mobile.citushealth.com\"},{\"config_key\": \"enable_multisite\", \"config_value\": \"0\"},{\"config_key\": \"enable_support_widget_branding\", \"config_value\": \"1\"},{\"config_key\": \"SMTP_domain\", \"config_value\": \"tx.npspharmacy.com\"},{\"config_key\": \"support_widget_from_email\", \"config_value\": \"no-reply@tx.npspharmacy.com\"}]','d27d320c27c3033b7883347d8beca317',20,1,NULL,1007,NULL,NULL,1,'Citus QA Regression Branch 1',1,NULL,'[{\"config_key\": \"app_short_link\", \"config_value\": \"\"},{\"config_key\": \"enable_support_widget_branding\", \"config_value\": \"\"},{\"config_key\": \"support_widget_from_email\", \"config_value\": \"\"},{\"config_key\": \"app_name\", \"config_value\": \"\"},{\"config_key\": \"SMTP_domain\", \"config_value\": \"\"},{\"config_key\": \"notification_language\", \"config_value\": \"es\"}]','es','es','10002_002','{\"INAPP\": \"[Recordatorio] Tiene un nuevo formulario para ser completado. Presione para verlo: {{INAPP_Short_Link}}\", \"Appless\": \"le han enviado un formulario de {{site/tenant}}. Presione para completar: {{Appless_Short_Link}} \"}','{\"INAPP\": \"[{{site/tenant}}] Tiene formulario(s) sin leer en {{appName}}\", \"Appless\": \"[Recordatorio] Tiene un nuevo formulario para ser completado\"}','Hola {{displayName}}','Atentamente',3,95,2);

Case-1:  run the below query 
select 
usersListSiteConfigs.*,
    JSON_OBJECT(
        'sms',
        MAX(
            CASE WHEN usersListSiteConfigs.notificationType = 2 THEN usersListSiteConfigs.content
         END
    ),
    'email',
    MAX(
        CASE WHEN usersListSiteConfigs.notificationType = 3 THEN usersListSiteConfigs.content
     END
),
'push',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 1 THEN usersListSiteConfigs.content
 END
)
) AS notificationContent,
JSON_OBJECT(
    'sms',
    MAX(
        CASE WHEN usersListSiteConfigs.notificationType = 2 THEN usersListSiteConfigs.emailSubject
     END
),
'email',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 3 THEN usersListSiteConfigs.emailSubject
 END
),
'push',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 1 THEN usersListSiteConfigs.emailSubject
 END
)
) AS notificationSubject,
JSON_OBJECT(
    'sms',
    MAX(
        CASE WHEN usersListSiteConfigs.notificationType = 2 THEN usersListSiteConfigs.salutation
     END
),
'email',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 3 THEN usersListSiteConfigs.salutation
 END
),
'push',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 1 THEN usersListSiteConfigs.salutation
 END
)
) AS notificationSalutation,
JSON_OBJECT(
    'sms',
    MAX(
        CASE WHEN usersListSiteConfigs.notificationType = 2 THEN usersListSiteConfigs.emailClosing
     END
),
'email',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 3 THEN usersListSiteConfigs.emailClosing
 END
),
'push',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 1 THEN usersListSiteConfigs.emailClosing
 END
)
) AS notificationClosingContent
from test_mad  usersListSiteConfigs;


------****************Check the output - >column Name - "notificationContent":
{"sms": null, "push": "{\"INAPP\": \"[Recordatorio] Usted tiene un nuevo formulario para ser completado\", \"Appless\": \"\"}", "email": null}

----**************************************
Step-2 : update the above select statement and include else '' as shown below:


    SELECT
    usersListSiteConfigs.*,
    JSON_OBJECT(
        'sms',
        MAX(
            CASE WHEN usersListSiteConfigs.notificationType = 2 THEN usersListSiteConfigs.content
         ELSE '' END
    ),
    'email',
    MAX(
        CASE WHEN usersListSiteConfigs.notificationType = 3 THEN usersListSiteConfigs.content
     ELSE '' END
),
'push',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 1 THEN usersListSiteConfigs.content
 ELSE '' END
)
) AS notificationContent,
JSON_OBJECT(
    'sms',
    MAX(
        CASE WHEN usersListSiteConfigs.notificationType = 2 THEN usersListSiteConfigs.emailSubject
     ELSE '' END
),
'email',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 3 THEN usersListSiteConfigs.emailSubject
 ELSE '' END
),
'push',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 1 THEN usersListSiteConfigs.emailSubject
 ELSE '' END
)
) AS notificationSubject,
JSON_OBJECT(
    'sms',
    MAX(
        CASE WHEN usersListSiteConfigs.notificationType = 2 THEN usersListSiteConfigs.salutation
     ELSE '' END
),
'email',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 3 THEN usersListSiteConfigs.salutation
 ELSE '' END
),
'push',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 1 THEN usersListSiteConfigs.salutation
 ELSE '' END
)
) AS notificationSalutation,
JSON_OBJECT(
    'sms',
    MAX(
        CASE WHEN usersListSiteConfigs.notificationType = 2 THEN usersListSiteConfigs.emailClosing
     ELSE '' END
),
'email',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 3 THEN usersListSiteConfigs.emailClosing
 ELSE '' END
),
'push',
MAX(
    CASE WHEN usersListSiteConfigs.notificationType = 1 THEN usersListSiteConfigs.emailClosing
ELSE '' END
)
) AS notificationClosingContent from test_mad usersListSiteConfigs
;

---Check the "notificationContent" column value from the above output. As you can see if we include "ELSE NULL" it is coming as expected.

{"sms": "{\"INAPP\": \"le han enviado un nuevo formulario de {{site/tenant}}. Presione para leerlo: {{INAPP_Short_Link}}. Responda HELP para obtener información adicional o STOP para cancelar el recibo de mensajes adicionales.\", \"Appless\": \"le han enviado un formulario de {{site/tenant}}. Presione para completar: {{Appless_Short_Link}} Responda HELP para obtener información adicional o STOP para cancelar el recibo de mensajes adicionales.\"}", "push": "{\"INAPP\": \"[Recordatorio] Usted tiene un nuevo formulario para ser completado\", \"Appless\": \"\"}", "email": "{\"INAPP\": \"[Recordatorio] Tiene un nuevo formulario para ser completado. Presione para verlo: {{INAPP_Short_Link}}\", \"Appless\": \"le han enviado un formulario de {{site/tenant}}. Presione para completar: {{Appless_Short_Link}} \"}"}

-----****Conclusion:
-----***  ELSE is working differently than case without else in Production instance. Where as the same query is running fine in QA with or without ELSE producing the same result.