Zend DB左连接

Question

I realize that Zend DB, Left Join SQL query return NULL for the join column. Is this true?

For example:

$selectmatchedtime = $this->dbo->select()
            ->from(array('v'=>'table1'))
            ->joinLeft(array('vc'=>'table2'),'vc.vid = v.vid');

Return null for all vid...

Answer 1

The problem is that vid column in your query belongs to two tables, but obviously can store only a single value in the result set. To resolve the problem, make an alias for it, stating explicitly which table should be used:

$selectmatchedtime = $this->dbo->select()
            ->from(array('v'=>'table1'))
            ->joinLeft(array('vc'=>'table2'),'vc.vid = v.vid')
            ->columns(array('vid'=>'v.vid'));