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// Syntax
for (variable | variable_list : [soql_query]) {
  code_block
}

//Example
insert new Account[]{new Account(Name = 'for loop 1'), 
                     new Account(Name = 'for loop 2'), 
                     new Account(Name = 'for loop 3')};

// The sObject list format executes the for loop once per returned batch
// of records
Integer i=0;
Integer j=0;
for (Account[] tmp : [SELECT Id FROM Account WHERE Name LIKE 'for loop _']) {
    j = tmp.size();
    i++;
}
System.assertEquals(3, j); // The list should have contained the three accounts
                       // named 'yyy'
System.assertEquals(1, i); // Since a single batch can hold up to 200 records and,
                       // only three records should have been returned, the 
                       // loop should have executed only once

Account[] acctsWithContacts = [SELECT Name, (SELECT FirstName,LastName FROM Contacts)
                               FROM Account 
                               WHERE Name = 'SFDC Computing'];
// Get child records
Contact[] cts = acctsWithContacts[0].Contacts;
System.debug('Name of first associated contact: ' 
             + cts[0].FirstName + ', ' + cts[0].LastName);

// use bind variable to add variable to the query using colon (:)
String targetDepartment = 'Wingo';
Contact[] techContacts = [SELECT FirstName, LastName
                          FROM Contact WHERE Department=:targetDepartment];

SELECT Name, Phone FROM Account 
  WHERE (Name = 'SFDC Computing' AND NumberOfEmployees > 25)
  ORDER BY Name ASC
  LIMIT 10