sql и xml

Question

Я пытаюсь выяснить, экспортировать ли данные из таблицы в XML-файл. Вот ситуация

Table1
contractID     subcontractid     ContractName     ContractType
123                              John             Electrical
123            1                 John             Comercial
123            2                 John             Resident
134                              Jim              Plumping
134            1                 Jim              Comercial
134            2                 Jim              Resindent

Я бы хотел, чтобы вывод XML-файла был следующим:

<contracts>
  <contract contractid = 123 contractname = john, contracttype = Electrical>
    <subcontract subcontractid = 1, contractname = John, contractType = Comercial />
    <subcontract subcontractid = 2, contractname = John, contractType = Resident />
  </contract>
  <contract contractid = 134 contractname = Jim, contracttype = Plumping>
    <subcontract subcontractid = 1, contractname = Jim, contractType = Comercial />
    <subcontract subcontractid = 2, contractname = Jim, contractType = Resident />
  </contract>
</contracts>

Спасибо за помощь.

Answer 1

Шиш, побежденный на 50 секунд! Я закажу тебе ламбак за скорость: -)

SELECT co.contractid AS '@contractid',
    co.contractname AS '@contractname',
        co.contracttype AS '@contractType'
        (SELECT sc.subcontractid AS '@subcontractid', 
        sc.contractname AS '@contractname', 
        sc.contractType AS '@contractType'
         FROM contract sc
     WHERE subcontractid IS NOT NULL AND sc.contractid = co.contractid
     FOR XML PATH('subcontract'),Type ) 
FROM Contract co
WHERE subcontractid IS NULL
FOR XML PATH('Contract'), ROOT('Contracts')

Answer 2

Для SQL Server 2005/2008 вы должны сделать что-то вроде:

SELECT 
    contractID as [@contractid], 
    ContractName as [@contractname], 
    ContractType As [@contracttype], 
    ( SELECT 
        subcontractid as [@subcontractid], 
        ContractName as [@contractname], 
        ContractType As [@contracttype] 
      FROM Table1 AS inner 
      WHERE outer.contractID=inner.contractID AND 
          subcontractid IS NOT NULL FOR XML PATH('subcontract'), TYPE ) as [node()] 
    WHERE subcontractid IS NULL
 FOR XML PATH('contract'), ROOT('contracts')

Для Oracle: что-то вроде:

SELECT XMLELEMENT('contracts', 
    (SELECT XMLELMENT('contract', 
        XMLAgg(
            XMLAttributes(
                contractID as 'contractid', 
                ContractName as 'contractname', 
                ContractType as 'contracttype'), 
           (SELECT XMLElement('subcontract', 
               XMLAgg(
                   XMLAttributes(
                       subcontractid as 'subcontractid', 
                       ContractName as 'contractname', 
                       ContractType as 'contracttype'
                   )
               ) 
            FROM Table1 AS inner 
            WHERE inner.contractID=outer.contractID AND subcontractid IS NOT NULL 
           )
         )   
      )
     FROM Table1 AS outer WHERE subcontractid IS NULL
    )
 )

Answer 3

Конкретный вариант базы данных будет иметь огромное значение в доступных вам опциях.

SQL Server, например, позволяет добавлять предложение «FOR XML» в конец запроса, но для oracle, mysql и других БД потребуются другие подходы.