Check if MongoDB database exists?

There are two possibilities to check if MongoDB database exists.

Case 1: The first possibility is that the MongoDB database exists i.e. it returns particular index.

Case 2: The second possibility is that the MongoDB database does not exist i.e. it returns index -1.

NOTE: An index starts from 0 and ends with (N-1) like an array.

The syntax is as follows to check if MongoDB database exists.

db.getMongo().getDBNames().indexOf("yourDatabaseName");

Case 1: Let us implement the above syntax to check if MongoDB database exists. Following is the query

db.getMongo().getDBNames().indexOf("test");

This will produce the following output

6

Look at the above sample output, we are getting 6 that means the database “test” exists and it is present at index 6.

Let us check all the databases now. Following is the query

> show dbs;

This will produce the following output

admin             0.001GB
config            0.000GB
local             0.000GB
sample            0.001GB
sampleDemo        0.000GB
studentSearch     0.000GB
test              0.009GB

Look at the above sample output, the database “test” exists and at index 6.

Case 2: If MongoDB database does not exist

> db.getMongo().getDBNames().indexOf("education");

The following is the output displaying -1 since the database “education” does not exist

-1