MongoDB lookup criteria

1. Relational operators

$eq is equal to

$lt is less than

$lte is less than or equal to

$gt is greater than

$gte is greater than or equal to

$in　　   is in scope

    // Query the names of "Xiao Ming" and "Xiao Gang" 
    $condition = [
         'name' => ['$in' => ['Xiao Ming', 'Xiao Gang' ]]
    ];
    $result = $collection -> find($condition,['_id'=>false]);

2. Logical Operators

$and　　and (the default logical relationship is and)

    // Query name whose age is greater than 10 and less than 30 
    $condition = [
         '$and' => [
            ['age' => ['$gt' => 10]],
            ['age' => ['$lt' => 30]]
        ]
    ];
    $result = $collection -> find($condition,['_id'=>false]);

　　Shorthand for $and　　:

    // Query name whose age is greater than 10 and less than 30 
    $condition = [
         'age' => ['$gt' => 10,'$lt' => 30 ]
    ];
    $result = $collection -> find($condition,['_id'=>false]);

$or　　or

     // Query name with age equal to 10 or equal to 30 
    $condition = [
         '$or' => [
            ['age' => ['$eq' => 10]],
            ['age' => ['$eq' => 30]]
        ]
    ];
    $result = $collection -> find($condition,['_id'=>false]);

$not　　not

    // Query name age is not equal to 10 
    $condition = [
         'age' => ['$not' => ['$eq' => 10 ]]
    ];
    $result = $collection -> find($condition,['_id'=>false]);

3. Array condition

• When the value of the property is an array, the query needs special handling
  • 　　In the query condition, the value of the attribute is a string, which means that the search condition contains the string

    // Query hobby containing swim 
    $condition = [
         'hobby' => 'swim'
    ];
    $result = $collection -> find($condition,['_id'=>false]);

• • 　　In the query condition, the value of the attribute contains multiple contents, which are connected using $all

    // Query 
    $condition in hobby that contains swim and climate = [
         'hobby' => ['$all' => ['swim','climb' ]]
    ];
    $result = $collection -> find($condition,['_id'=>false]);

• • 　　In the query condition, the value of the attribute is an array, indicating that it is strictly equal to the element of the array

    // The query hobby is the 
    $condition of swim and climate = [
         'hobby' => ['swim','climb' ]
    ];
    $result = $collection -> find($condition,['_id'=>false]);

4. Embedded Documentation

The embedded document behaves like the value of the property is again a document

For example: {

　　　　"name":"小明",

　　　　"score":{

　　　　　　"Math":100,

　　　　　　"Chinese”:90

　　　　}

　　　}

• Get the property value of the embedded document through .dot 

    // Query math scores greater than 80 
    $condition = [
         'score.math' => ['$gt' => 80 ]
    ];
    $result = $collection -> find($condition,['_id'=>false]);

5. Regular filtering

filter using regular expressions

    // Query names starting with "small" 
    $condition = [
         'name' => new MongoRegex('/^small/' )
    ];
    $result = $collection -> find($condition,['_id'=>false]);

6. Sort

Note: You need to query first, and then sort the results of the query

Sort by the sort method of the query result ( cursor ) , there are two ways to sort:

• • 1 positive sequence
  • -1　　reverse order

    // Query results 
    $cursor = $collection -> find([],['_id'=> false ]);
     // Sort the query results in reverse order 
    $result = $cursor -> sort (['score.math'=> -1 ]);
     foreach ( $result  as  $key => $value ){
         echo ( $value ['name'].':'. $value ['score']['math']).'<br/ >' ;
    }

7. Limited quantity

Limit the results of the query, this method belongs to the cursor cursor

• • how much skip()　　ignores
  • limit()　　how much to keep

     // Query results 
    $cursor = $collection -> find([],['_id'=> false ]);
     // Sort the query results in reverse order, ignore the first three, and keep the last two 
    $result = $cursor 
        -> sort (['score.math'=>-1 ])
         -> skip(3 )
         -> limit(2 );
     foreach ( $result  as  $key => $value ){
         echo ( $value ['name']. ':'. $value ['score']['math']).'<br/>' ;
    }