what will be the mm query in TYPO3 version 9 - typo3

Question

As $GLOBALS['TYPO3_DB'] become obsolete, I am stuck at the following mm query.
$dbObj = $GLOBALS['TYPO3_DB']->exec_SELECT_mm_query('distinct tx_news_domain_model_news.uid',
'sys_category',
'sys_category_record_mm',
'tx_news_domain_model_news',
' AND sys_category_record_mm.uid_local IN ( '.$catUid.' ) AND tx_news_domain_model_news.pid='.$pid.' AND sys_category_record_mm.tablenames="tx_news_domain_model_news"',
'',
'',
''
);
It shows
Call to a member function exec_SELECT_mm_query() on null
Has anyone found any solution?
Thanks

Answer 1

Use the new QueryBuilder and join your relation.
Example (not a tested working example):
$table = 'tx_news_domain_model_news';
$joinTable = 'sys_category_record_mm';
$queryBuilder = GeneralUtility::makeInstance(ConnectionPool::class)->getQueryBuilderForTable($table);
$statement = $queryBuilder
->select('*')
->from($table)
->leftJoin(
$table,
$joinTable,
'categoryMM',
$queryBuilder->expr()->eq(
'categoryMM.uid_foreign',
$queryBuilder->quoteIdentifier('tx_news_domain_model_news.uid')
)
)
->where(
$queryBuilder->expr()->eq('categoryMM.tablenames', $table),
$queryBuilder->expr()->eq('categoryMM.fieldname', 'categories'),
$queryBuilder->expr()->eq(
'categoryMM.uid',
$queryBuilder->createNamedParameter($catUid, \PDO::PARAM_INT)
)
)
->execute();

Answer 2

I'm using this where an older version of news has related contents stored in an MM table.
$selectTable = 'tt_content';
$joinTable = 'tx_news_domain_model_news';
$mmTable = 'tx_news_domain_model_news_ttcontent_mm';
/** #var \TYPO3\CMS\Core\Database\Query\QueryBuilder $queryBuilder */
$queryBuilder = GeneralUtility::makeInstance(\TYPO3\CMS\Core\Database\ConnectionPool::class)->getQueryBuilderForTable('tt_content');
$res = $queryBuilder->select('t.*')->from($selectTable, 't')
->leftJoin('t', $mmTable, 'mm',
$queryBuilder->expr()->andX(
$queryBuilder->expr()->eq('mm.uid_local', $queryBuilder->createNamedParameter($newsRecord['uid'])),
$queryBuilder->expr()->eq('mm.uid_foreign', $queryBuilder->quoteIdentifier('t.uid'))
)
)
->leftJoin('mm', $joinTable, 'n',
$queryBuilder->expr()->eq('mm.uid_local', $queryBuilder->quoteIdentifier('n.uid'))
)
->where(
$queryBuilder->expr()->gt('n.uid', $queryBuilder->createNamedParameter(0))
)->execute()->fetchAll();