如何在使用数据库功能的Yii中计算查询结果？

Question

I tried the following

// find all keywords that have an uppercase
$upperKeywords = Keyword::find()->where('lower(keyword) != keyword')->orderBy('id');
echo "Found keyword with uppercase: ".$upperKeywords->count().PHP_EOL;
$count = (new Query())->select('count(*)')->from($upperKeywords)->scalar();

The first count attempt gives this error:

Exception 'yii\db\Exception' with message 'SQLSTATE[42803]: Grouping error: 7 ERROR:  column "keyword.id" must appear in the GROUP BY clause or be used in an aggregate function
LINE 1: ...FROM "keyword" WHERE lower(keyword) != keyword ORDER BY "id"
                                                                   ^
The SQL being executed was: SELECT COUNT(*) FROM "keyword" WHERE lower(keyword) != keyword ORDER BY "id"'

The second count attempt gives this error:

PHP Warning 'yii\base\ErrorException' with message 'trim() expects parameter 1 to be string, object given'

in /cygdrive/c/Users/Chloe/workspace/ShopWiz/vendor/yiisoft/yii2/db/Query.php:486

Stack trace:
#0 [internal function]: yii\base\ErrorHandler->handleError(2, 'trim() expects ...', '/cygdrive/c/Use...', 486, Array)
#1 /cygdrive/c/Users/Chloe/workspace/ShopWiz/vendor/yiisoft/yii2/db/Query.php(486): trim(Object(yii\db\ActiveQuery))

Answer 1

Shoot, I should have scrolled down more. This worked. The array treats it as a subquery and the key value is the table alias.

$count = (new Query())->select('count(*)')->from(['t' => $upperKeywords])->scalar();

http://www.yiiframework.com/doc-2.0/guide-db-query-builder.html#from