MiracleHu · April 1, 2020 07:13 · Oct 11, 2019 · Jul 16, 2019
diff --git a/mongodb_cheat_sheet.md b/mongodb_cheat_sheet.md
@@ -228,7 +228,7 @@ db.posts.update({ title: 'Post One' },
 db.posts.find({
   comments: {
      $elemMatch: {
-       author: 'Mary Williams'
+       user: 'Mary Williams'
        }
     }
   }

diff --git a/mongodb_cheat_sheet.md b/mongodb_cheat_sheet.md
@@ -0,0 +1,261 @@
+# MongoDB Cheat Sheet
+
+## Show All Databases
+
+```
+show dbs
+```
+
+## Show Current Database
+
+```
+db
+```
+
+## Create Or Switch Database
+
+```
+use acme
+```
+
+## Drop
+
+```
+db.dropDatabase()
+```
+
+## Create Collection
+
+```
+db.createCollection('posts')
+```
+
+## Show Collections
+
+```
+show collections
+```
+
+## Insert Row
+
+```
+db.posts.insert({
+  title: 'Post One',
+  body: 'Body of post one',
+  category: 'News',
+  tags: ['news', 'events'],
+  user: {
+    name: 'John Doe',
+    status: 'author'
+  },
+  date: Date()
+})
+```
+
+## Insert Multiple Rows
+
+```
+db.posts.insertMany([
+  {
+    title: 'Post Two',
+    body: 'Body of post two',
+    category: 'Technology',
+    date: Date()
+  },
+  {
+    title: 'Post Three',
+    body: 'Body of post three',
+    category: 'News',
+    date: Date()
+  },
+  {
+    title: 'Post Four',
+    body: 'Body of post three',
+    category: 'Entertainment',
+    date: Date()
+  }
+])
+```
+
+## Get All Rows
+
+```
+db.posts.find()
+```
+
+## Get All Rows Formatted
+
+```
+db.find().pretty()
+```
+
+## Find Rows
+
+```
+db.posts.find({ category: 'News' })
+```
+
+## Sort Rows
+
+```
+# asc
+db.posts.find().sort({ title: 1 }).pretty()
+# desc
+db.posts.find().sort({ title: -1 }).pretty()
+```
+
+## Count Rows
+
+```
+db.posts.find().count()
+db.posts.find({ category: 'news' }).count()
+```
+
+## Limit Rows
+
+```
+db.posts.find().limit(2).pretty()
+```
+
+## Chaining
+
+```
+db.posts.find().limit(2).sort({ title: 1 }).pretty()
+```
+
+## Foreach
+
+```
+db.posts.find().forEach(function(doc) {
+  print("Blog Post: " + doc.title)
+})
+```
+
+## Find One Row
+
+```
+db.posts.findOne({ category: 'News' })
+```
+
+## Find Specific Fields
+
+```
+db.posts.find({ title: 'Post One' }, {
+  title: 1,
+  author: 1
+})
+```
+
+## Update Row
+
+```
+db.posts.update({ title: 'Post Two' },
+{
+  title: 'Post Two',
+  body: 'New body for post 2',
+  date: Date()
+},
+{
+  upsert: true
+})
+```
+
+## Update Specific Field
+
+```
+db.posts.update({ title: 'Post Two' },
+{
+  $set: {
+    body: 'Body for post 2',
+    category: 'Technology'
+  }
+})
+```
+
+## Increment Field (\$inc)
+
+```
+db.posts.update({ title: 'Post Two' },
+{
+  $inc: {
+    likes: 5
+  }
+})
+```
+
+## Rename Field
+
+```
+db.posts.update({ title: 'Post Two' },
+{
+  $rename: {
+    likes: 'views'
+  }
+})
+```
+
+## Delete Row
+
+```
+db.posts.remove({ title: 'Post Four' })
+```
+
+## Sub-Documents
+
+```
+db.posts.update({ title: 'Post One' },
+{
+  $set: {
+    comments: [
+      {
+        body: 'Comment One',
+        user: 'Mary Williams',
+        date: Date()
+      },
+      {
+        body: 'Comment Two',
+        user: 'Harry White',
+        date: Date()
+      }
+    ]
+  }
+})
+```
+
+## Find By Element in Array (\$elemMatch)
+
+```
+db.posts.find({
+  comments: {
+     $elemMatch: {
+       author: 'Mary Williams'
+       }
+    }
+  }
+)
+```
+
+## Add Index
+
+```
+db.posts.createIndex({ title: 'text' })
+```
+
+## Text Search
+
+```
+db.posts.find({
+  $text: {
+    $search: "\"Post O\""
+    }
+})
+```
+
+## Greater & Less Than
+
+```
+db.posts.find({ views: { $gt: 2 } })
+db.posts.find({ views: { $gte: 7 } })
+db.posts.find({ views: { $lt: 7 } })
+db.posts.find({ views: { $lte: 7 } })
+```