Difference between revisions of "FIND Tutorial"

Use find() to show the details of Germany.

Show Germany instead of France.

db.world.find({name: 'France'});

db.world.find({name: 'Germany'});

You can use .pretty() to make the output more readable.

List all the countries in the continent of "Eurasia".

db.world.find({name: 'Germany'}).pretty();

db.world.find({continent: "Eurasia"}).pretty();

You can test numbers as well as strings.

Find the country with an area of exactly 43094.

db.world.find({gdp: 3425956000000}).pretty();

db.world.find({area: 43094}).pretty();

You can use $gt (greater than) and $lt (less than) to compare numbers and strings.

Show each country with a population of over 250000000
Sort the results alphabetically.

You will need to use a projection FIND_Examples#Using_a_projection_with_find to answer this question.

db.world.find(
  {area: {$gt: 9000000}},
  {name: 1, _id: 0}
).sort(
  {name: 1}
).pretty();

db.world.find({population:{$gt:250000000}},{name:1,_id:0}).sort({name: 1}).pretty();

Greater than and less than comparisons can also be applied to strings.

List the countries that come after "S" in the alphabet.

db.world.find();

db.world.find({name:{$gt:"S"}},{name:1,_id:0}).pretty();

Find the name and capital cities for countries with a population of over 70 million.

db.world.findOne();

db.world.find({population:{$gt:70000000}},{name:1,capital:1,_id:0}).pretty();

Find the countries that have a population that is over 200 million or less than 20,000.

db.world.find(
  {$or: [
    {name: 'Germany'},
    {name: 'France'}
  ]},
  {name: 1, population: 1, _id: 0}
);

db.world.find({$or:[{population:{$gt:200000000}},{population:{$lt:20000}}]},{name:1,population:1,_id:0})