Can anyone help me with Itereating through a multiselect picklist?

I need to make a list of all entries using a for loop.

Is there an equivalent of the standard DISTINCT statement for SOQL (SELECT DISTINCT email from Some_Table) like ther eis in standard SQL? There is a DISTINCT COUNT(field).....but I am looking for just DISTINCT so that duplicate values are not returned?

Thanks

I have these number of records in the database for the following queries:

Total Parent__c records = 2800

Total Child__c records  = 77,800

On an average, each parent has around 30 childs.

When I run the following piece of code, I get a governor limit error (query row). Note that I get retrieving only 10 parent records! I still get this error. I  debug log says that only 177 records out of allowed 10,000 were retrieved.  Seems like there is some issue with Childs__r.size() statement. 

for (Parent__c p: [select Name,
(select Name from Childs__r)
from Parent__c limit 20] {
i++;
System.debug('i is ' + i);
System.debug('Name is ' +p.Name);
Double count =p.Childs__r.size();
System.debug('Child Count is ' + count);


}

System Log says:

12:44:31 ERROR - Evaluation error: System.QueryException: Aggregate query has too many rows for direct assignment, use FOR loop

Resource usage for namespace: (default)

Number of SOQL queries: 1 out of 100

Number of query rows: 177 out of 10000

Number of SOSL queries: 0 out of 20

Number of DML statements: 0 out of 100

Number of DML rows: 0 out of 10000

Number of script statements: 51 out of 200000 

When I write a differenr query where I get 1100 Parents, the query ran for 6 minutes and and I loop through every child of it,  I am able to go through 29678 records (i=29678).  The debug log says that that number of query rows is 1267...records...what's going on? 

for (Parent__c p: [select Name,
(select Name from Childs__r)
from Parent__c limit 1100] {

for (Child__c c:p.Childs__r) {

i++;
System.Debug(‘Child Name is ‘ + c.Name);
}

}

System.debug('i is ' + i);

 Debug Log:

Resource usage for namespace: (default)

Number of SOQL queries: 1 out of 100

Number of query rows: 1267 out of 10000

Number of SOSL queries: 0 out of 20

Number of DML statements: 0 out of 100

Number of DML rows: 0 out of 10000

Number of script statements: 59362 out of 200000

Maximum heap size: 938 out of 1000000