CollectionFind::fields

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CollectionFind::fields — Set document field filter

说明

public mysql_xdevapi\CollectionFind mysql_xdevapi\CollectionFind::fields ( string $projection )

This is the equivalent of the SQL projection, which allows to select which columns the query shall return.

参数

projection: Can either be a single string or an array of string, those strings are identifying the columns that have to be returned for each document that match the search condition.

返回值

A CollectionFind object that can be used for further processing

范例

Example #1 mysql_xdevapi\CollectionFind::fields() example


<?php

//Assuming $coll is a valid collection object

/*
   The following find call will search for all the documents
   with a 'job' like 'tassinaro' and will return only the column
   'age' from each document
*/
$res = $coll->find('job like \'tassinaro\'')->fields('age')->execute();

//Example which make use of the COUNT function
    $res = $coll->find()->fields(['COUNT(name) as cn', 'MAX(age) as ma', 'job as j'])->execute();
    

?>