MALFORMED_QUERY: Opportunity__r.LeadSource != 'Website'); ^ ERROR at Row:3:Column:89 unexpected token: ;
SELECT Id, OwnerId, WhatId,Reminder_Date_Time__c, WhoId,Record_Type_Name__c, Task_Type__c,
Assigned_Date__c, Task_Status__c, ActivityDate, Subject, Attended_By__c,Is_Assigned__c
FROM Task
WHERE (Task_Status__c != 'Closed') AND ( Opportunity__r.LeadSource != 'Website')
SOQL queries do not end with a semi-colon. Please remove the semi-colon from the end of your query. The parentheses are also optional.
SELECT Id, OwnerId, WhatId,Reminder_Date_Time__c, WhoId,Record_Type_Name__c, Task_Type__c,
Assigned_Date__c, Task_Status__c, ActivityDate, Subject, Attended_By__c,
Is_Assigned__c
FROM Task
WHERE Task_Status__c != 'Closed' AND Opportunity__r.LeadSource != 'Website'
You can try this dynamic soql.
String query = 'SELECT Id, OwnerId, WhatId, Reminder_Date_Time__c, WhoId, Record_Type_Name__c, Task_Type__c, Assigned_Date__c, Task_Status__c, ActivityDate, Subject, Attended_By__c,Is_Assigned__c '+
+'FROM Task '+
+'WHERE Task_Status__c != \'Closed\' AND (NOT Opportunity__r.LeadSource LIKE \'%Website%\')';
System.debug(query);
Refer this link for more details http://raydehler.com/cloud/clod/soql-sosl-using-not-like.html
For more on Quoted String Escape Sequences
SELECT Id, OwnerId, WhatId,Reminder_Date_Time__c, WhoId, Record_Type_Name__c, Task_Type__c,Assigned_Date__c, Task_Status__c, ActivityDate, Subject, Attended_By__c,Is_Assigned__c FROM Task WHERE (NOT Task_Status__c LIKE 'Closed') AND( Opportunity__r.LeadSource != 'Website') .. Still i m getting wrong results