David Loveday

queries.sql

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+PRAGMA foreign_keys = ON;
+
+CREATE TABLE organization (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    name VARCHAR(128)
+);
+
+CREATE TABLE user (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    name VARCHAR(128),
+    organization_id INTEGER REFERENCES organization(id)
+
+);
+CREATE TABLE channel (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    name VARCHAR(128),
+    organization_id INTEGER REFERENCES organization(id)
+);
+
+
+CREATE TABLE channel_user (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    channel_id INTEGER REFERENCES channel(id),
+    user_id INTEGER REFERENCES user(id)
+);
+
+CREATE TABLE message (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    content VARCHAR(2056) NOT NULL,
+    timestamp DATE DEFAULT (datetime('now', 'localtime')),
+    channel_id INTEGER REFERENCES channel(id),
+    user_id INTEGER REFERENCES user(id)
+);
+
+
+INSERT INTO organization (name) VALUES ("Lambda School");
+
+INSERT INTO channel (name, organization_id) VALUES ("#general", 1);
+INSERT INTO channel (name, organization_id) VALUES ("#random", 1);
+
+INSERT INTO user (name, organization_id ) VALUES ("Alice", 1);
+INSERT INTO user (name, organization_id ) VALUES ("Bob", 1);
+INSERT INTO user (name, organization_id ) VALUES ("Chris", 1);
+
+INSERT INTO channel_user (channel_id, user_id) VALUES (1,1);
+INSERT INTO channel_user (channel_id, user_id) VALUES (2,1);
+INSERT INTO channel_user (channel_id, user_id) VALUES (1,2);
+INSERT INTO channel_user (channel_id, user_id) VALUES (2,3);
+
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Alice's post in #general", 1, 1);
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Alice's post in #random", 2, 1);
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Alice's post in #general again", 1, 1);
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Bob's first post in #random", 2, 2);
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Bob's  second post  in #general", 1, 2);
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Bob's third post in #general again", 1, 2);
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Chris' first post in #random", 2, 3);
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Chris' post in #general", 1, 3);
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Chris' second post in #random", 2, 3);
+INSERT INTO message (content, channel_id,  user_id) VALUES ("Another by Alice in #random", 2, 1);
+
+
+-- List all organization names
+SELECT * FROM organization;
+
+-- List all channel names
+SELECT * FROM channel;
+
+-- List all channels in a specific organization by name
+SELECT channel.name FROM channel, organization
+WHERE organization_id = organization.id
+AND organization.name = "Lambda School";
+
+-- List all messages in a specific channel by channel name #general in order of timestamp, descending
+SELECT content FROM message, channel
+WHERE channel_id = channel.id 
+AND channel.name = "#general" 
+ORDER BY timestamp DESC;
+
+-- List all channels to which user Alice belongs
+SELECT channel.name FROM channel, user, channel_user  
+WHERE user.id = user_id
+AND channel.id = channel_id
+AND user.name = "Alice";
+
+-- List all users that belong to channel #general
+SELECT user.name FROM channel, user, channel_user 
+WHERE user_id = user.id
+AND channel.id = channel_id
+AND channel.name = "#general";
+
+-- List all messages in all channels by user Alice
+SELECT message.*, channel.name 
+FROM message, channel, user, channel_user 
+WHERE message.user_id = channel_user.id 
+AND channel_user.channel_id = channel.id 
+AND channel_user.user_id = user.id 
+AND user.name = "Alice";
+
+SELECT content FROM message, user
+WHERE user_id = user.id
+AND user.name = 'Alice';
+
+-- List all messages in #random by user Bob
+SELECT content FROM Message, channel, user
+WHERE user_id = user.id
+AND channel_id = channel.id
+AND channel.name = "#random"
+AND User.name = "Bob";
+
+-- List the count of messages across all channels per user
+SELECT user.name  AS "User Name", COUNT(*) "Message Count" FROM user, message
+WHERE user_id = user.id
+GROUP BY user.id 
+ORDER BY user.name DESC
+
+
+-- Question: What SQL keywords or concept would you use if you wanted to automatically delete all 
+-- messages by a user if that user were deleted from the user table?
+-- Ans: Add "ON DELETE CASCADE" to the end of a target id
+