Autosave: 2024-11-14 14:43:31

neuron/c1b90fbf-731a-4de6-8c95-0dece40b5017/SQLite.md

@@ -5,6 +5,16 @@ created: Wednesday, November 13, 2024
 
 # SQLite
 
+## Enabling foreign key constraints
+
+Foreign key constraints are not enabled by default - it is very permissive. You
+must manually turn them on, as part of the connection process:
+
+```py
+connection = sqlite3.connect("my_database.db")
+connection.execute("PRAGMA foreign_keys = ON")
+```
+
 ## INSERT OR IGNORE INTO
 
 If table has a `UNIQUE` constraint on a field, insert if it is unique otherwise

neuron/c1b90fbf-731a-4de6-8c95-0dece40b5017/Using_SQLite_with_Python.md

@@ -51,6 +51,9 @@ print(cursor.fetchall())
 # (tags)
 ```
 
+Note that it is necessary to `commit` the changes. The cursor object just stores
+the operation in memory and does not execute until you specifically commit them.
+
 ## Prepared statements and parameterised queries
 
 ### Parameterised queries
@@ -67,13 +70,12 @@ Alternatively, pass the [tuple](Tuples_in_Python.md) directly:
 ```python
 login_data = ("thomas", "123")
 cursor.execute("SELECT * FROM users WHERE username = ? AND password = ?",
-               login_data)
-
+login_data)
 ```
 
 ### Prepared statements
 
-> With prepared statements you have to pass in the parameters
+> With prepared statements you have to pass in the parameters as a dictionary
 
 ```python
 user_data = {
@@ -81,5 +83,14 @@ user_data = {
     "email": "thomas@email.com"
 }
 
-cursor.execute("INSERT INTO users (username, email) VALUES (:username, :email)")
+cursor.execute("INSERT INTO users (username, email) VALUES (:username, :email)",
+               user_data)
+```
+
+In the example above it so happens that we already have a dictionary we are
+working with. If you want to use a prepared statement and you don't have a
+dictionary already, you will need to construct one as part of the query, e.g:
+
+```python
+cursor.execute("INSERT INTO table_name (value_one, value_two) VALUES (:value_one, :value_two)", { value_one: 'foo', value_two: 'bar'})
 ```

neuron/c1b90fbf-731a-4de6-8c95-0dece40b5017/index.md

@@ -13,15 +13,15 @@ computer science.
 
 ![not-by-ai-badge](static/not-by-ai-alternative--light.svg)
  
-**Build ID:** 4e66db01-35b6-4b9c-aab8-2a0429e30df2
+**Build ID:** c1b90fbf-731a-4de6-8c95-0dece40b5017
 
-**Published:** Thu 14 Nov 2024 14:15:51
+**Published:** Thu 14 Nov 2024 14:43:30
 
 ### Recent edits 
 
-- [[Working_with_directories_in_Python]] 
-- [[SQLite]] 
 - [[Using_SQLite_with_Python]] 
+- [[SQLite]] 
+- [[Working_with_directories_in_Python]] 
 - [[Usenet]] 
 - [[Batch_processing]] 
 - [[0716531c_rewilding_the_internet]] 

zk/SQLite.md

@@ -5,6 +5,16 @@ created: Wednesday, November 13, 2024
 
 # SQLite
 
+## Enabling foreign key constraints
+
+Foreign key constraints are not enabled by default - it is very permissive. You
+must manually turn them on, as part of the connection process:
+
+```py
+connection = sqlite3.connect("my_database.db")
+connection.execute("PRAGMA foreign_keys = ON")
+```
+
 ## INSERT OR IGNORE INTO
 
 If table has a `UNIQUE` constraint on a field, insert if it is unique otherwise

zk/Using_SQLite_with_Python.md

@@ -51,6 +51,9 @@ print(cursor.fetchall())
 # (tags)
 ```
 
+Note that it is necessary to `commit` the changes. The cursor object just stores
+the operation in memory and does not execute until you specifically commit them.
+
 ## Prepared statements and parameterised queries
 
 ### Parameterised queries
@@ -67,13 +70,12 @@ Alternatively, pass the [tuple](Tuples_in_Python.md) directly:
 ```python
 login_data = ("thomas", "123")
 cursor.execute("SELECT * FROM users WHERE username = ? AND password = ?",
-               login_data)
-
+login_data)
 ```
 
 ### Prepared statements
 
-> With prepared statements you have to pass in the parameters
+> With prepared statements you have to pass in the parameters as a dictionary
 
 ```python
 user_data = {
@@ -81,5 +83,14 @@ user_data = {
     "email": "thomas@email.com"
 }
 
-cursor.execute("INSERT INTO users (username, email) VALUES (:username, :email)")
+cursor.execute("INSERT INTO users (username, email) VALUES (:username, :email)",
+               user_data)
+```
+
+In the example above it so happens that we already have a dictionary we are
+working with. If you want to use a prepared statement and you don't have a
+dictionary already, you will need to construct one as part of the query, e.g:
+
+```python
+cursor.execute("INSERT INTO table_name (value_one, value_two) VALUES (:value_one, :value_two)", { value_one: 'foo', value_two: 'bar'})
 ```