vault backup: 2024-05-18 18:18:04

Affected files: content/.obsidian/plugins/recent-files-obsidian/data.json content/.obsidian/workspace.json content/postgresql/PostgreSQL Conflict.md content/postgresql/PostgreSQL Constraints.md content/postgresql/PostgreSQL Delete.md content/postgresql/PostgreSQL Insert and Import.md content/postgresql/PostgreSQL Sequence and UUID.md content/postgresql/PostgreSQL Update.md content/postgresql/PostgreSQL.md
windsuzu · May 18, 2024 · a94dc69 · a94dc69
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diff --git a/content/.obsidian/plugins/recent-files-obsidian/data.json b/content/.obsidian/plugins/recent-files-obsidian/data.json
@@ -1,17 +1,13 @@
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+      "basename": "PostgreSQL Conflict",
+      "path": "postgresql/PostgreSQL Conflict.md"
     },
     {
       "basename": "PostgreSQL",
       "path": "postgresql/PostgreSQL.md"
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@@ -28,14 +24,6 @@
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-      "path": "postgresql/PostgreSQL Database.md"
-    },
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@@ -44,10 +32,26 @@
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+    {
+      "basename": "PostgreSQL Sequence and UUID",
+      "path": "postgresql/PostgreSQL Sequence and UUID.md"
+    },
     {
       "basename": "Connect PostgreSQL on WSL 2 (Ubuntu)",
       "path": "postgresql/Connect PostgreSQL on WSL 2 (Ubuntu).md"
     },
+    {
+      "basename": "PostgreSQL Database",
+      "path": "postgresql/PostgreSQL Database.md"
+    },
+    {
+      "basename": "PostgreSQL Table",
+      "path": "postgresql/PostgreSQL Table.md"
+    },
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+      "path": "postgresql/PostgreSQL Join.md"
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+    "postgresql/PostgreSQL Sequence and UUID.md",
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@@ -298,8 +276,6 @@
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diff --git a/content/postgresql/PostgreSQL Conflict.md b/content/postgresql/PostgreSQL Conflict.md
@@ -0,0 +1,20 @@
+---
+draft: false
+date: 2024-05-18 17:48
+tags:
+  - postgres
+---
+
+
+
+```sql
+ON CONFLICT (id) DO NOTHING;
+ON CONFLICT (id) DO UPDATE SET email = EXCLUDED.email;
+ON CONFLICT (id) DO UPDATE SET email = EXCLUDED.email, gender = EXCLUDED.gender;
+```
+
+
+
+
+> [!info] References
+> - [Learn PostgreSQL Tutorial - Full Course for Beginners (youtube.com)](https://www.youtube.com/watch?v=qw--VYLpxG4) 
diff --git a/content/postgresql/PostgreSQL Constraints.md b/content/postgresql/PostgreSQL Constraints.md
@@ -1,6 +1,6 @@
 ---
 draft: false
-date: 2024-05-17 23:32
+date: 2024-05-18 17:36
 tags:
   - postgres
 ---
@@ -10,35 +10,45 @@ Other than [[PostgreSQL Primary Key and Foreign Key|primary and foreign keys]],
 ### NOT NULL
 
 ```sql
+-- Define NOT NULL constraint when creating table
 CREATE TABLE example (
     name VARCHAR(100) NOT NULL
 );
 
+-- Define NOT NULL constriant by modifying table
 ALTER TABLE example ALTER COLUMN name SET NOT NULL;
 
+-- Remove NOT NULL constraint by modifying table
 ALTER TABLE example ALTER COLUMN name DROP NOT NULL;
 ```
 ### UNIQUE
 
 ```sql
+-- Define UNIQUE constraint when creating table
 CREATE TABLE example (
     email VARCHAR(150) UNIQUE
 );
 
+-- Define UNIQUE constraint by modifying table with named constraint
 ALTER TABLE example ADD CONSTRAINT unique_email UNIQUE (email);
+-- Define UNIQUE constraint by modifying table without naming constraint
 ALTER TABLE example ADD UNIQUE (email);
 
+-- Remove UNIQUE constraint by modifying table
 ALTER TABLE example DROP CONSTRAINT unique_email;
 ```
 ### CHECK
 
 ```sql
+-- Define CHECK constraint when creating table
 CREATE TABLE example (
     age INT CHECK (age >= 18)
 );
 
+-- Define CHECK constraint by modifying table with named constraint
 ALTER TABLE example ADD CONSTRAINT check_age CHECK (age >= 18);
 
+-- Remove CHECK constraint by modifying table
 ALTER TABLE example DROP CONSTRAINT check_age;
 ```
 

diff --git a/content/postgresql/PostgreSQL Delete.md b/content/postgresql/PostgreSQL Delete.md
@@ -1,21 +1,22 @@
 ---
 draft: false
-date: 2024-05-16 18:17
+date: 2024-05-18 17:47
 tags:
   - postgres
 ---
 
+To delete all records in your table:
 
 ```sql
 DELETE FROM person;
 ```
 
+To delete one or more records using conditions:
+
 ```sql
 DELETE FROM person WHERE id = 1; 
 ```
 
 
-
-
 > [!info] References
 > - [Learn PostgreSQL Tutorial - Full Course for Beginners (youtube.com)](https://www.youtube.com/watch?v=qw--VYLpxG4)
diff --git a/content/postgresql/PostgreSQL Insert and Import.md b/content/postgresql/PostgreSQL Insert and Import.md
@@ -1,6 +1,6 @@
 ---
 draft: false
-date: 2024-05-16 11:49
+date: 2024-05-18 17:37
 tags:
   - postgres
 ---
@@ -25,7 +25,7 @@ INSERT INTO person (first_name, last_name, email, gender, date_of_birth) VALUES
 Suppose you have a `.sql` file with 1000 insert statements, you can use `\i file_relative_path` to execute all the commands in the file.
 
 ```sql
-# /mnt/c/Users/winds/Desktop/person.sql
+-- /mnt/c/Users/winds/Desktop/person.sql
 
 insert into person (first_name, last_name, email, gender, date_of_birth) values ('Alvan', 'Fearnall', null, 'Male', '2024-05-12');
 insert into person (first_name, last_name, email, gender, date_of_birth) values ('Herbie', 'Tollit', null, 'Male', '2023-12-18');

diff --git a/content/postgresql/PostgreSQL Sequence and UUID.md b/content/postgresql/PostgreSQL Sequence and UUID.md
@@ -1,6 +1,6 @@
 ---
 draft: false
-date: 2024-05-17 23:37
+date: 2024-05-18 17:23
 tags:
   - postgres
 ---
@@ -15,10 +15,33 @@ ALTER SEQUENCE person_id_seq RESTART WITH 1;
 
 ### UUID
 
+[UUID](https://en.wikipedia.org/wiki/Universally_unique_identifier) stands for Universally Unique Identifier and is a data type designed to store unique identifiers. A UUID is globally unique, which means it is unique even across different systems.
 
+```sql
+CREATE TABLE example (
+    id UUID PRIMARY KEY,
+    name VARCHAR(100)
+);
+```
 
+Before inserting a record with a UUID, you have to install a UUID generator from `uuid-ossp`. You can install it with the following SQL command.
 
+```sql
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+```
 
+Now when you insert a record, you can call `uuid_generate_v4()` or [other versions can be found in the documentation](https://www.postgresql.org/docs/current/uuid-ossp.html) for your `id` field.
+
+```sql
+-- Inserting a single row with a generated UUID
+INSERT INTO example (id, name) VALUES (uuid_generate_v4(), 'John');
+
+-- Inserting multiple rows with generated UUIDs
+INSERT INTO example (id, name) 
+VALUES 
+    (uuid_generate_v4(), 'Alice'),
+    (uuid_generate_v4(), 'Bob');
+```
 
 
 > [!info] References

diff --git a/content/postgresql/PostgreSQL Update.md b/content/postgresql/PostgreSQL Update.md
@@ -1,21 +1,15 @@
 ---
 draft: false
-date: 2024-05-16 18:16
+date: 2024-05-18 17:47
 tags:
   - postgres
 ---
 
+To update a single record in the database, use the following SQL statement:
+
 ```sql
 UPDATE person SET first_name = 'Omar', last_name = 'Montana' WHERE id = 2011;
 ```
-```sql
-ON CONFLICT (id) DO NOTHING;
-ON CONFLICT (id) DO UPDATE SET email = EXCLUDED.email;
-ON CONFLICT (id) DO UPDATE SET email = EXCLUDED.email, gender = EXCLUDED.gender;
-```
-
-
-
 
 > [!info] References
 > - [Learn PostgreSQL Tutorial - Full Course for Beginners (youtube.com)](https://www.youtube.com/watch?v=qw--VYLpxG4)
diff --git a/content/postgresql/PostgreSQL.md b/content/postgresql/PostgreSQL.md
@@ -1,6 +1,6 @@
 ---
 draft: false
-date: 2024-05-17 22:56
+date: 2024-05-18 17:46
 tags:
   - postgres
 ---
@@ -24,6 +24,7 @@ tags:
 - [[PostgreSQL Select]]
 - [[PostgreSQL Update]]
 - [[PostgreSQL Delete]]
+- [[PostgreSQL Conflict]]
 - [[PostgreSQL Join]]
 
 > [!info] References