<?php

namespace KC;

use KC\Database\DatabaseQuery;

use KC\Database\QueryBuilderSelect;

use KC\Database\QueryBuilderInsert;

use KC\Database\QueryBuilderUpdate;

use KC\Database\QueryBuilderDelete;

use KC\Database\DatabaseExpression;

/**

* Provides a shortcut to get Database related objects for [making queries](../database/query).

*

* Shortcut | Returned Object

* -------------|---------------

* [`DB::query()`](#query) | [DatabaseQuery]

* [`DB::insert()`](#insert) | [QueryBuilderInsert]

* [`DB::select()`](#select),<br />[`DB::select_array()`](#select_array) | [QueryBuilderSelect]

* [`DB::update()`](#update) | [QueryBuilderUpdate]

* [`DB::delete()`](#delete) | [QueryBuilderDelete]

* [`DB::expr()`](#expr) | [DatabaseExpression]

*

* You pass the same parameters to these functions as you pass to the objects they return.

*/

class DB {

/**

* Create a new [DatabaseQuery] of the given type.

*

* // Create a new SELECT query

* $query = DB::query(DatabaseConnection::SELECT, 'SELECT * FROM users');

*

* // Create a new DELETE query

* $query = DB::query(DatabaseConnection::DELETE, 'DELETE FROM users WHERE id = 5');

*

* Specifying the type changes the returned result. When using

* `DatabaseConnection::SELECT`, a [DatabaseResult] will be returned.

* `DatabaseConnection::INSERT` queries will return the insert id and number of rows.

* For all other queries, the number of affected rows is returned.

*

* @param integer $type type: DatabaseConnection::SELECT, etc

* @param string $sql SQL statement

* @return Database_Query

*/

public static function query($type, $sql)

{

return new DatabaseQuery($type, $sql);

}

/**

* Create a new [QueryBuilderSelect]. Each argument will be

* treated as a column. To generate a `foo AS bar` alias, use an array.

*

* // SELECT id, username

* $query = DB::select('id', 'username');

*

* // SELECT id AS user_id

* $query = DB::select(['id', 'user_id']);

*

* @param mixed $columns column name or array($column, $alias) or object

* @return QueryBuilderSelect

*/

public static function select($columns = null)

{

return new QueryBuilderSelect(func_get_args());

}

/**

* Create a new [QueryBuilderSelect] from an array of columns.

*

* // SELECT id, username

* $query = DB::selectArray(array('id', 'username'));

*

* @param array $columns columns to select

* @return QueryBuilderSelect

*/

public static function selectArray(array $columns = null)

{

return new QueryBuilderSelect($columns);

}

/**

* Create a new [QueryBuilderInsert].

*

* // INSERT INTO users (id, username)

* $query = DB::insert('users', array('id', 'username'));

*

* @param string $table table to insert into

* @param array $columns list of column names or array($column, $alias) or object

* @return QueryBuilderInsert

*/

public static function insert($table = null, array $columns = null)

{

return new QueryBuilderInsert($table, $columns);

}

/**

* Create a new [QueryBuilderUpdate].

*

* // UPDATE users

* $query = DB::update('users');

*

* @param string $table table to update

* @return QueryBuilderUpdate

*/

public static function update($table = null)

{

return new QueryBuilderUpdate($table);

}

/**

* Create a new [QueryBuilderDelete].

*

* // DELETE FROM users

* $query = DB::delete('users');

*

* @param string $table table to delete from

* @return QueryBuilderDelete

*/

public static function delete($table = null)

{

return new QueryBuilderDelete($table);

}

/**

* Create a new [DatabaseExpression] which is not escaped. An expression

* is the only way to use SQL functions within query builders.

*

* $expression = DB::expr('COUNT(users.id)');

* $query = DB::update('users')->set(array('login_count' => DB::expr('login_count + 1')))->where('id', '=', $id);

*

* @param string $string expression

* @param array parameters

* @return DatabaseExpression

*/

public static function expr($string, $parameters = [])

{

return new DatabaseExpression($string, $parameters);

}

}