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MongoDB is a powerful NoSQL database server. It uses JSON-like documents with optional schema to store data.

Organizing data is always an essential task for developers as it plays the most critical role in the performance of the application. In MongoDB, you can LIKEfetch data using queries similar to SQL statements.

Creating a Database in MongoDB

We will use some dummy data in the examples in this tutorial. You can also create the database and execute the commands given below to insert the dummy data.

db={
    "colors": [
        {
            "id": 100,
            "color": "Pink"
        },
        {
            "id": 101,
            "color": "Purple"
        },
        {
            "id": 102,
            "color": "Black"
        },
        {
            "id": 103,
            "color": "Blue"
        }
    ]
}

db.collection.find()Methods in MongoDB

When searching in a MongoDB collection, the most critical part is a flexible and direct db.collection.find()method.

Using , you can easily query a collection of documents db.collection.find(),by passing it a few simple parameters and returning one .光标

游标is just a result set. We can iterate over it to manipulate or otherwise use 光标the pointed-to documents.

db.collection.find()A simple example of the method is shown below.

> db.colors.find()

Output:

The above program returns all the documents in a collection. But this is very rare for production requirements.

You always need some filtered results from the database.

For example, if you want to get color: Pinkall the data containing . Execute the following query.

>  db.colors.find({color: "Pink"})

Output:

The query using db.collection.find()the method is similar to the SQL LIKE statement in MongoDB

You can use regular expressions to search for documents in MongoDB. This will be similar to LIKEthe statement in SQL query.

Now that you are using .find()to query your collection, you can change your syntax slightly and start looking for matches based on words or phrases that may be partial matches in specific fields, similar to how SQL engines use LIKEthe operator.

This technique makes use of regular expressions (regex), which are text strings that define a search pattern. Several regular expression engines are written with different syntaxes, but the basic principle is the same.

At the most basic level, a regular expression is /a string of characters enclosed in a single slash ( ).

db.collection.find({
    "k": /pattern/
})

But currently, since shell regular expressions mongoplayground.netdon't work when querying, you can use the expression given below.

db.collection.find({
    "k": {
        "$regex": "pattern"
    }
})

For example, if you want to perform the same query as above using regular expressions and find out how many documents contain the color Pink, you can "Pink"replace the string with /Pink/.

Use db.collection.find()the method to search for a matching string anywhere

The first statement searches for all documents where the color name contains anywhere in the string Pink. The second statement searches for Blall records where the color name contains .

The SQL statement for this query:

select * from colors where color LIKE "%Pink%"

The MongoDB statement for this query:

db.colors.find({
    "color": {
        "$regex": "Pink"
    }
})

Output:

The MongoDB statement for this query:

db.colors.find({
    "color": {
        "$regex": "Bl"
    }
})

Output:

Using regular expressions instead of standard quoted strings, you can start looking for partial word or phrase matches.

Use the method with ^to db.collection.find()search for the starting characters of a matching string

This will match all Pstrings that begin with the characters . For example, the carrot symbol is used ^.

The SQL statement for this query:

select * from colors where color LIKE "P%"

The MongoDB statement for this query:

db.colors.find({
    "color": {
        "$regex": "^P"
    }
})

Output:

Use the method with $to db.collection.find()search for a matching end-of-string character

The dollar $sign matches a string that ends with a specific character.

The following example matches all kstrings ending with the characters .

The SQL statement for this query:

select * from colors where color LIKE "%k"

The MongoDB statement for this query:

db.colors.find({
    "color": {
        "$regex": "k$"
    }
})

Output:

Use db.collection.find()the method and isearch for matching strings in any case

By default the method searches case-sensitively. However, you can instruct the command to match characters in any case db.collection.findusing the -e option used below .ifind

The SQL statement for this query:

select * from colors where color LIKE BINARY "pink"

The MongoDB statement for this query:

db.colors.find({
    "color": {
        "$regex": "k$/i"
    }
})

Output:

This MongoDB tutorial article teaches you how to search a database in MongoDB similar to SQL LIKEstatements.