MongoDB\Collection::distinct()
定义
参数
$fieldName: string- 返回唯一值的字段。
$filter: array|object- 指定从哪些文档中检索唯一值的筛选条件。
$options: array指定所需选项的数组。
返回值
不同值的数组。
错误/异常
MongoDB\Exception\UnexpectedValueException 如果命令响应来自服务器的数据格式不正确。
MongoDB\Exception\UnsupportedException 如果使用了所选服务器不支持选项（例如 collation，readConcern，writeConcern）。
MongoDB\Exception\InvalidArgumentException 用于与参数或选项解析相关的错误。
MongoDB\Driver\Exception\RuntimeException 用于扩展级别其他错误（例如连接错误）。
行为
When evaluating query criteria, MongoDB compares types and values according to its own comparison rules for BSON types, which differs from PHP's comparison and type juggling rules. When matching a special BSON type the query criteria should use the respective BSON class in the extension (e.g. use MongoDB\BSON\ObjectId to match an ObjectId).
示例
返回字段的唯一值
以下示例标识了在测试数据库中restaurants集合中borough字段的唯一值。
$collection = (new MongoDB\Client)->test->restaurants; $distinct = $collection->distinct('borough'); var_dump($distinct);
输出将类似于
array(6) { [0]=> string(5) "Bronx" [1]=> string(8) "Brooklyn" [2]=> string(9) "Manhattan" [3]=> string(7) "Missing" [4]=> string(6) "Queens" [5]=> string(13) "Staten Island" }
使用过滤器返回唯一值
以下示例标识了在测试数据库中restaurants集合中cuisine字段的唯一值，条件是文档中的borough为Queens
$collection = (new MongoDB\Client)->test->restaurants; $distinct = $collection->distinct('cuisine', ['borough' => 'Queens']); var_dump($distinct);
输出将类似于
array(75) { [0]=> string(6) "Afghan" [1]=> string(7) "African" [2]=> string(9) "American " [3]=> string(8) "Armenian" [4]=> string(5) "Asian" [5]=> string(10) "Australian" [6]=> string(15) "Bagels/Pretzels" [7]=> string(6) "Bakery" [8]=> string(11) "Bangladeshi" [9]=> string(8) "Barbecue" [10]=> string(55) "Bottled beverages, including water, sodas, juices, etc." [11]=> string(9) "Brazilian" [12]=> string(4) "Cafe" [13]=> string(16) "Café/Coffee/Tea" [14]=> string(5) "Cajun" [15]=> string(9) "Caribbean" [16]=> string(7) "Chicken" [17]=> string(7) "Chinese" [18]=> string(13) "Chinese/Cuban" [19]=> string(16) "Chinese/Japanese" [20]=> string(11) "Continental" [21]=> string(6) "Creole" [22]=> string(5) "Czech" [23]=> string(12) "Delicatessen" [24]=> string(6) "Donuts" [25]=> string(16) "Eastern European" [26]=> string(8) "Egyptian" [27]=> string(7) "English" [28]=> string(8) "Filipino" [29]=> string(6) "French" [30]=> string(17) "Fruits/Vegetables" [31]=> string(6) "German" [32]=> string(5) "Greek" [33]=> string(10) "Hamburgers" [34]=> string(16) "Hotdogs/Pretzels" [35]=> string(31) "Ice Cream, Gelato, Yogurt, Ices" [36]=> string(6) "Indian" [37]=> string(10) "Indonesian" [38]=> string(5) "Irish" [39]=> string(7) "Italian" [40]=> string(8) "Japanese" [41]=> string(13) "Jewish/Kosher" [42]=> string(30) "Juice, Smoothies, Fruit Salads" [43]=> string(6) "Korean" [44]=> string(64) "Latin (Cuban, Dominican, Puerto Rican, South & Central American)" [45]=> string(13) "Mediterranean" [46]=> string(7) "Mexican" [47]=> string(14) "Middle Eastern" [48]=> string(8) "Moroccan" [49]=> string(25) "Not Listed/Not Applicable" [50]=> string(18) "Nuts/Confectionary" [51]=> string(5) "Other" [52]=> string(9) "Pakistani" [53]=> string(16) "Pancakes/Waffles" [54]=> string(8) "Peruvian" [55]=> string(5) "Pizza" [56]=> string(13) "Pizza/Italian" [57]=> string(6) "Polish" [58]=> string(10) "Portuguese" [59]=> string(7) "Russian" [60]=> string(6) "Salads" [61]=> string(10) "Sandwiches" [62]=> string(30) "Sandwiches/Salads/Mixed Buffet" [63]=> string(7) "Seafood" [64]=> string(9) "Soul Food" [65]=> string(18) "Soups & Sandwiches" [66]=> string(12) "Southwestern" [67]=> string(7) "Spanish" [68]=> string(5) "Steak" [69]=> string(5) "Tapas" [70]=> string(7) "Tex-Mex" [71]=> string(4) "Thai" [72]=> string(7) "Turkish" [73]=> string(10) "Vegetarian" [74]=> string(29) "Vietnamese/Cambodian/Malaysia" }
另请参阅
distinct 命令参考，请参阅MongoDB手册