Update documentation for BLOB support and data type handling

- CHANGELOG.md : details on BLOB support and automatic MIME type detection
- Add examples in extensions-to-sql.md illustrating data type conversions and JSON object structure
- Update SQL examples in migrations to reflect new BLOB handling capabilities

Author: lovasoa

CHANGELOG.md

@@ -11,15 +11,15 @@
    - Since modals have their own url inside the page, you can now link to a modal from another page, and if you refresh a page while the modal is open, the modal will stay open.
    - modals now have an `open` parameter to open the modal automatically when the page is loaded.
  - New [download](https://sql-page.com/component.sql?component=download) component to let the user download files. The files may be stored as BLOBs in the database, local files on the server, or may be fetched from a different server.
- - Enhanced BLOB Support. You can now return binary data (BLOBs) directly to sqlpage, and it will automatically convert them to data URLs. This allows you to use database BLOBs directly wherever a link is expected, including in the new download component.
-   - **PostgreSQL**: supports `BYTEA` columns
-   - **MySQL/MariaDB**: supports `BLOB` columns
-   - **MSSQL**: Extended support for `VARBINARY`, `BIGVARBINARY`, `BINARY`, and `IMAGE` columns
-   - **SQLite**: Full support for `BLOB` columns
-   - **Smart MIME Type Detection**: Automatic detection of common file types based on magic bytes:
-     - **Images**: PNG, JPEG/JPG, GIF, BMP, WebP, SVG
-     - **Documents**: PDF, DOCX, XLSX, PPTX
-     - **Data**: JSON, XML, ZIP archives
+ - **Enhanced BLOB Support**. You can now return binary data (BLOBs) directly to sqlpage, and it will automatically convert them to data URLs. This allows you to use database BLOBs directly wherever a link is expected, including in the new download component.
+   - supports columns of type `BYTEA` (PostgreSQL), `BLOB` (MySQL, SQLite), `VARBINARY` and `IMAGE` (mssql)
+   - Automatic detection of common file types based on magic bytes
+   - This means you can use a BLOB wherever an image url is expected. For instance:
+     ```sql
+     select 'list' as component;
+     select username as title, avatar_blob as image_url
+     from users;
+     ```
 
 ## v0.36.1
  - Fix regression introduced in v0.36.0: PostgreSQL money values showed as 0.0

examples/official-site/extensions-to-sql.md

@@ -206,3 +206,52 @@ SET post_id = COALESCE($post_id, 0);
 -- Prepared statement (SQLite syntax)
 SELECT COALESCE(CAST(?1 AS TEXT), 0)
 ```
+
+# Data types
+
+Each database has its own rich set of data types.
+The data modal in SQLPage itself is simpler, mainly composed of text strings and json objects.
+
+### From the user to SQLPage
+
+Form fields and URL parameters may contain arrays. These are converted to JSON strings before processing.
+
+For instance, Loading `users.sql?user[]=Tim&user[]=Tom` will result in a single variable `$user` with the textual value `["Tim", "Tom"]`.
+
+### From SQLPage to the database
+
+SQLPage sends only text strings (`VARCHAR`) and `NULL`s to the database, since these are the only possible variable and function return values.
+
+### From the database to SQLPage
+
+Each row of data returned by a SQL query is converted to a JSON object before being passed to components.
+
+- Each column becomes a key in the json object. If a row has two columns of the same name, they become an array in the json object.
+- Each value is converted to the closest JSON value
+  - all number types map to json numbers, booleans to booleans, and `NULL` to `null`,
+  - all text types map to json strings
+  - date and time types map to json strings containing ISO datetime values
+  - binary values (BLOBs) map to json strings containing [data URLs](https://developer.mozilla.org/en-US/docs/Web/URI/Reference/Schemes/data)
+
+#### Example
+
+The following PostgreSQL query:
+
+```sql
+select
+    1 as one,
+    'x' as my_array, 'y' as my_array,
+    now() as today,
+    '<svg></svg>'::bytea as my_image;
+```
+
+will result in the following JSON object being passed to components for rendering
+
+```json
+{
+    "one" : 1,
+    "my_array" : ["x","y"],
+    "today":"2025-08-30T06:40:13.894918+00:00",
+    "my_image":"data:image/svg+xml;base64,PHN2Zz48L3N2Zz4="
+}
+```

examples/official-site/extensions-to-sql.sql

@@ -1,7 +1,10 @@
 select 'http_header' as component,
 	'public, max-age=300, stale-while-revalidate=3600, stale-if-error=86400' as "Cache-Control";
 
-select 'dynamic' as component, properties FROM example WHERE component = 'shell' LIMIT 1;
+select 'dynamic' as component, json_patch(json_extract(properties, '$[0]'), json_object(
+    'title', 'SQLPage - Extensions to SQL'
+)) as properties
+FROM example WHERE component = 'shell' LIMIT 1;
 
 -- Article by Matthew Larkin
 select 'text' as component,

examples/official-site/sqlpage/migrations/65_download.sql

@@ -104,7 +104,25 @@ select
         '
 ## Serve an image stored as a BLOB in the database
 
-In PostgreSQL, you can use the [encode(bytes, format)](https://www.postgresql.org/docs/current/functions-binarystring.html#FUNCTION-ENCODE) function to encode the file content as Base64.
+### Automatically detect the mime type
+
+If you have a table with a column `content` that contains a BLOB
+(depending on the database, the type may be named `BYTEA`, `BLOB`, `VARBINARY`, or `IMAGE`),
+you can just return its contents directly, and SQLPage will automatically detect the mime type,
+and convert it to a data URL.
+
+```sql
+select
+    ''download'' as component,
+    content as data_url
+from document
+where id = $doc_id;
+```
+
+### Customize the mime type
+
+In PostgreSQL, you can use the [encode(bytes, format)](https://www.postgresql.org/docs/current/functions-binarystring.html#FUNCTION-ENCODE) function to encode the file content as Base64,
+and manually create your own data URL.
 
 ```sql
 select