### Install Nette Database via Composer

Source: https://github.com/nette/database/blob/master/readme.md

Installs the Nette Database library using Composer. This is the recommended installation method. It requires PHP version 8.1 or higher.

```bash
composer require nette/database
```

--------------------------------

### Example SQL Query

Source: https://github.com/nette/database/blob/master/readme.md

A sample SQL query that might be executed by the Nette Database layer, demonstrating table selection and potential column names.

```sql
SELECT * FROM `book`
```

--------------------------------

### Get a Specific Row with ActiveRow

Source: https://github.com/nette/database/blob/master/readme.md

Retrieves a single row from a table by its primary key using the `get()` method. This method directly returns an `ActiveRow` instance for the specified record.

```php
$book = $explorer->table('book')->get(2);

echo $book->title;
echo $book->author_id;
```

--------------------------------

### Create Nette Database Connection

Source: https://github.com/nette/database/blob/master/readme.md

Instantiates the Nette Database Explorer, which acts as a wrapper around PDO. It takes DSN, username, and password as arguments, similar to PDO's constructor.

```php
$database = new Nette\Database\Explorer($dsn, $user, $password);
```

--------------------------------

### Initial Database Queries

Source: https://github.com/nette/database/blob/master/readme.md

These SQL queries represent the initial state before caching is applied, potentially selecting all columns (`*`) or a broader set of columns than strictly needed for subsequent operations.

```sql
SELECT * FROM `author` WHERE (`author`.`id` IN (11, 12))
SELECT * FROM `book_tag` WHERE (`book_tag`.`book_id` IN (1, 4, 2, 3))
SELECT * FROM `tag` WHERE (`tag`.`id` IN (21, 22, 23))
```

--------------------------------

### Execute Database Queries with Parameters

Source: https://github.com/nette/database/blob/master/readme.md

Demonstrates executing various SQL queries (INSERT, UPDATE, SELECT) using the `query` method. It supports passing parameters as arrays, DateTime objects, file handles, and using placeholders for safe query execution.

```php
$database->query('INSERT INTO users', [
	'name' => 'Jim',
	'created' => new DateTime,
	'avatar' => fopen('image.gif', 'r'),
], ...);

$database->query('UPDATE users SET ? WHERE id=?', $data, $id);
$database->query('SELECT * FROM categories WHERE id=?', 123)->dump();
```

--------------------------------

### Database Transaction Commands

Source: https://github.com/nette/database/blob/master/tests/Database.Tracy/panel.html

Demonstrates standard SQL transaction control commands used in database operations. Includes BEGIN TRANSACTION, COMMIT, and ERROR handling.

```sql
BEGIN TRANSACTION
```

```sql
COMMIT
```

```sql
ERROR
```

--------------------------------

### Database Query Execution and Logging

Source: https://github.com/nette/database/blob/master/tests/Database.Tracy/panel.html

Illustrates the execution of a SQL query within a file context, including potential error reporting. The format suggests logging from a tool that tracks file origins and execution status.

```APIDOC
File: Explorer.php
Line: [line_number]
Status: [SUCCESS|ERROR]
Query: [SQL_QUERY_OR_COMMAND]
Trace: [Optional_Trace_Information]
```

--------------------------------

### Fetch Data with Nette Database Explorer

Source: https://github.com/nette/database/blob/master/readme.md

Shows how to select data from a table using the `table()` method and iterate over the results. Each row is returned as an `ActiveRow` object, allowing property access to column data.

```php
$selection = $explorer->table('book');

foreach ($selection as $book) {
	echo $book->title;
	echo $book->author_id;
}
```

--------------------------------

### Nette Arrays Utility Function

Source: https://github.com/nette/database/blob/master/tests/Database.Tracy/panel.html

Shows the usage of the invoke method from the Nette\Utils\Arrays class, likely for applying a callback to array elements.

```php
Nette\Utils\Arrays::invoke()
```

--------------------------------

### Work with Relationships in Nette Database

Source: https://github.com/nette/database/blob/master/readme.md

Illustrates how to access related data from other tables using properties (e.g., `$book->author->name`) and the `related()` method for many-to-many relationships (e.g., `$book->related('book_tag')`). This approach optimizes query execution.

```php
$books = $explorer->table('book');

foreach ($books as $book) {
	echo 'title:      ' . $book->title;
	echo 'written by: ' . $book->author->name;

	echo 'tags: ';
	foreach ($book->related('book_tag') as $bookTag) {
		echo $bookTag->tag->name . ', ';
	}
}
```

--------------------------------

### Basic SQL Query

Source: https://github.com/nette/database/blob/master/tests/Database.Tracy/panel.html

A simple SQL SELECT statement, often used for health checks or retrieving minimal data.

```sql
SELECT 1
```

--------------------------------

### Optimized Queries with Caching

Source: https://github.com/nette/database/blob/master/readme.md

After enabling caching, Nette Database Explorer stores used column names and executes subsequent queries only with the required columns, leading to more efficient data retrieval.

```sql
SELECT `id`, `title`, `author_id` FROM `book`
SELECT `id`, `name` FROM `author` WHERE (`author`.`id` IN (11, 12))
SELECT `book_id`, `tag_id` FROM `book_tag` WHERE (`book_tag`.`book_id` IN (1, 4, 2, 3))
SELECT `id`, `name` FROM `tag` WHERE (`tag`.`id` IN (21, 22, 23))
```

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