javascript - How to write this sql using the join method in thinkphp?

SELECT a.,count() as num FROM sys_article a join sys_comment b on a.article_id=b.article_id where a.article_id=20

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SELECT a.,count() as num FROM sys_article a join sys_comment b on a.article_id=b.article_id where a.article_id=20

<code>$Article->field('sys.article.article_id, count(*) as count')->join('__ARTICLE__ ON __COMMENT__.article_id = __ARTICLE__.article_id')->where('sys.article.article_id = 20')->select();</code>