Difference between revisions of "FIND Tutorial"
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==Working with the <code>world</code> collection of countries== | ==Working with the <code>world</code> collection of countries== | ||
<p> | <p> | ||
| − | This tutorial introduces NoSQL using MongoDB. We will be using the < | + | This tutorial introduces NoSQL using MongoDB. We will be using the <syntaxhighlight lang="JavaScript" inline>find()</syntaxhighlight > |
command and comparison functions on the collection '''world''' which contains details of around 250 countries of the world: | command and comparison functions on the collection '''world''' which contains details of around 250 countries of the world: | ||
</p> | </p> | ||
| Line 8: | Line 8: | ||
==Show Germany== | ==Show Germany== | ||
<div class="q" data-lang="mongo"> | <div class="q" data-lang="mongo"> | ||
| − | Use < | + | Use <syntaxhighlight lang="JavaScript" inline>find()</syntaxhighlight> to show the details of Germany. |
<p class="strong"> | <p class="strong"> | ||
Show Germany instead of France. | Show Germany instead of France. | ||
</p> | </p> | ||
| − | <pre class="def"><nowiki>db.world.find({name:'France'});</nowiki></pre> | + | <pre class="def"><nowiki>db.world.find({name: 'France'});</nowiki></pre> |
| − | <pre class="ans"><nowiki>db.world.find({name:'Germany'});</nowiki></pre> | + | <pre class="ans"><nowiki>db.world.find({name: 'Germany'});</nowiki></pre> |
</div> | </div> | ||
==Eurasia== | ==Eurasia== | ||
<div class="q" data-lang="mongo"> | <div class="q" data-lang="mongo"> | ||
| − | You can use < | + | You can use <syntaxhighlight lang="JavaScript" inline>.pretty()</syntaxhighlight> to make the output more readable. |
<p class="strong"> | <p class="strong"> | ||
List all the countries in the continent of "Eurasia". | List all the countries in the continent of "Eurasia". | ||
</p> | </p> | ||
| − | <pre class="def"><nowiki>db.world.find({name:'Germany'}).pretty();</nowiki></pre> | + | <pre class="def"><nowiki>db.world.find({name: 'Germany'}).pretty();</nowiki></pre> |
| − | <pre class="ans"><nowiki>db.world.find({continent:"Eurasia"}).pretty();</nowiki></pre> | + | <pre class="ans"><nowiki>db.world.find({continent: "Eurasia"}).pretty();</nowiki></pre> |
</div> | </div> | ||
| Line 32: | Line 32: | ||
Find the country with an area of exactly 43094. | Find the country with an area of exactly 43094. | ||
</p> | </p> | ||
| − | <pre class="def"><nowiki>db.world.find({gdp:3425956000000}).pretty();</nowiki></pre> | + | <pre class="def"><nowiki>db.world.find({gdp: 3425956000000}).pretty();</nowiki></pre> |
| − | <pre class="ans"><nowiki>db.world.find({area:43094}).pretty();</nowiki></pre> | + | <pre class="ans"><nowiki>db.world.find({area: 43094}).pretty();</nowiki></pre> |
</div> | </div> | ||
| Line 79: | Line 79: | ||
db.world.find( | db.world.find( | ||
{$or: [ | {$or: [ | ||
| − | {name:'Germany'}, | + | {name: 'Germany'}, |
| − | {name:'France'} | + | {name: 'France'} |
]}, | ]}, | ||
{name: 1, population: 1, _id: 0} | {name: 1, population: 1, _id: 0} | ||
Revision as of 14:17, 17 October 2018
Contents
Working with the world collection of countries
This tutorial introduces NoSQL using MongoDB. We will be using the find()
command and comparison functions on the collection world which contains details of around 250 countries of the world:
FIND examples are available.
Show Germany
Use find() to show the details of Germany.
Show Germany instead of France.
db.world.find({name: 'France'});
db.world.find({name: 'Germany'});
Eurasia
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();
Find an area
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();
Using $gt
You can use $gt (greater than) and $lt (less than) to compare numbers and strings.
Show each country with a population of over 250000000
Sort the results alphabetically.
db.world.find(
{area: {$gt: 9000000}},
{name: 1, _id: 0}
).sort(
{name: 1}
).pretty();
db.world.find({population:{$gt:250000000}},{name:1,_id:0}).sort({name: 1}).pretty();
After S
List the countries that come after "S" in the alphabet.
db.world.findOne();
db.world.find({name:{$gt:"S"}},{name:1,_id:0}).pretty();
Name and Capital
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();
Using $or
Find the countries that have a population that is over 200 million or less than 20,000.
db.world.find(
{$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})
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