vault backup: 2024-05-16 18:49:36

Affected files: content/.obsidian/plugins/recent-files-obsidian/data.json content/.obsidian/workspace.json content/postgresql/PostgreSQL Constraint and Key.md content/postgresql/PostgreSQL Database.md content/postgresql/PostgreSQL Delete.md content/postgresql/PostgreSQL Join.md content/postgresql/PostgreSQL Sequence and UUID.md content/postgresql/PostgreSQL Table.md content/postgresql/PostgreSQL Update.md content/postgresql/PostgreSQL.md
windsuzu · May 16, 2024 · 2c8a060 · 2c8a060
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@@ -1,24 +1,44 @@
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+    },
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@@ -179,26 +199,6 @@
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diff --git a/content/postgresql/PostgreSQL Constraint and Key.md b/content/postgresql/PostgreSQL Constraint and Key.md
@@ -0,0 +1,54 @@
+---
+draft: false
+date: 2024-05-16 18:19
+tags:
+  - postgres
+---
+
+
+
+```sql
+ALTER TABLE person ADD UNIQUE (email);
+ALTER TABLE person ADD CONSTRAINT unique_email UNIQUE (email);
+```
+
+```sql
+ALTER TABLE person DROP CONSTRAINT person_pkey;
+```
+
+```sql
+ALTER TABLE person ADD PRIMARY KEY (id);
+```
+
+```sql
+ALTER TABLE person ADD CONSTRAINT gender_contraint CHECK (gender = 'Female' OR gender = 'Male');
+```
+
+```sql
+CREATE TABLE car (
+	id BIGSERIAL NOT NULL PRIMARY KEY,
+	make VARCHAR(100) NOT NULL,
+	model VARCHAR(100) NOT NULL,
+	price NUMERIC(19,2) NOT NULL
+);
+
+CREATE TABLE person (
+	id BIGSERIAL NOT NULL PRIMARY KEY,
+	first_name VARCHAR(50) NOT NULL,
+	last_name VARCHAR(50) NOT NULL,
+	gender VARCHAR(50) NOT NULL,
+	date_of_birth DATE NOT NULL,
+	email VARCHAR(150),
+	car_id BIGINT REFERENCE car(id),
+	UNIQUE(car_id)
+);
+```
+
+
+```sql
+UPDATE person SET car_id = 2 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 Databases.md → content/postgresql/PostgreSQL Database.md b/content/postgresql/PostgreSQL Databases.md → content/postgresql/PostgreSQL Database.md
diff --git a/content/postgresql/PostgreSQL Delete.md b/content/postgresql/PostgreSQL Delete.md
@@ -0,0 +1,21 @@
+---
+draft: false
+date: 2024-05-16 18:17
+tags:
+  - postgres
+---
+
+
+```sql
+DELETE FROM person;
+```
+
+```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 Join.md b/content/postgresql/PostgreSQL Join.md
@@ -0,0 +1,39 @@
+---
+draft: false
+date: 2024-05-16 18:17
+tags:
+  - postgres
+---
+
+
+### JOIN
+
+```sql
+JOIN car ON person.car_id = car.id;
+```
+
+```sql
+SELECT person.first_name, car.make, car.price
+FROM person
+JOIN car ON person.car_id = car.id
+```
+
+```sql
+SELECT person.first_name, car.make, car.price
+FROM person
+LEFT JOIN car ON person.car_id = car.id
+```
+
+```sql
+SELECT person.first_name, car.make, car.price
+FROM person
+JOIN car USING (car_uid)
+```
+
+
+
+
+
+
+> [!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 Sequence and UUID.md b/content/postgresql/PostgreSQL Sequence and UUID.md
@@ -0,0 +1,24 @@
+---
+draft: false
+date: 2024-05-16 18:15
+tags:
+  - postgres
+---
+
+### BIGSERIAL
+
+```sql
+ALTER SEQUENCE person_id_seq RESTART WITH 0;
+```
+
+### UUID
+
+
+
+
+
+
+
+> [!info] References
+> - [Learn PostgreSQL Tutorial - Full Course for Beginners (youtube.com)](https://www.youtube.com/watch?v=qw--VYLpxG4)
+> - [Universally unique identifier - Wikipedia](https://en.wikipedia.org/wiki/Universally_unique_identifier)
diff --git a/content/postgresql/PostgreSQL Tables.md → content/postgresql/PostgreSQL Table.md b/content/postgresql/PostgreSQL Tables.md → content/postgresql/PostgreSQL Table.md
@@ -1,6 +1,6 @@
 ---
 draft: false
-date: 2024-05-16 11:49
+date: 2024-05-16 17:20
 tags:
   - postgres
 ---
@@ -83,9 +83,32 @@ And use `\d table_name` to see the details of the specified table.
 #     "person_pkey" PRIMARY KEY, btree (id)
 ```
 
+### Update a table
+
+To update a table, use `ALTER`. For example, you can update the column name by using `ALTER TABLE` with `RENAME TO`:
+
+```sql
+ALTER TABLE table_name RENAME column_name TO column_new_name;
+
+ALTER TABLE person RENAME id TO person_uid;
+ALTER TABLE person RENAME gender TO sex;
+```
+
+Additionally, you can update the column type by using `ALTER TABLE` with `ALTER COLUMN` and `TYPE`:
+
+```sql
+ALTER TABLE table_name ALTER COLUMN column_name TYPE type_name;
+
+ALTER TABLE person ALTER COLUMN email TYPE varchar(300);
+ALTER TABLE person ALTER COLUMN age TYPE int;
+```
 ### Remove a table
 
-To remove a table, simply use `DROP TABLE table_name`.
+To remove a table, use `DROP` to do so.
+
+```sql
+DROP TABLE table_name;
+```
 
 > [!info] References
 > - [Learn PostgreSQL Tutorial - Full Course for Beginners - YouTube](https://www.youtube.com/watch?v=qw--VYLpxG4)