Add method to retrieve foreign keys for a table to driver classes

core/abstract/abstract_driver.php

@@ -49,6 +49,12 @@ abstract class Abstract_Driver extends \PDO implements Driver_Interface {
 	 */
 	public $util;
 
+	/**
+	 * Reference to table_builder class
+	 * @var \Query\Table\Table_Builder
+	 */
+	public $table;
+
 	/**
 	 * Last query executed
 	 * @var string
@@ -81,6 +87,8 @@ abstract class Abstract_Driver extends \PDO implements Driver_Interface {
 			$class = get_class($this) . "_{$sub}";
 			$this->$sub = new $class($this);
 		}
+
+		$this->table = new \Query\Table\Table_Builder('', array(), $this);
 	}
 
 	// --------------------------------------------------------------------------
@@ -394,6 +402,19 @@ abstract class Abstract_Driver extends \PDO implements Driver_Interface {
 
 	// --------------------------------------------------------------------------
 
+	/**
+	 * Retrieve foreign keys for the table
+	 *
+	 * @param string $table
+	 * @return array
+	 */
+	public function get_fks($table)
+	{
+		return $this->driver_query($this->sql->fk_list($table), FALSE);
+	}
+
+	// --------------------------------------------------------------------------
+
 	/**
 	 * Retrieve list of data types for the database
 	 *

core/interfaces/sql_interface.php

@@ -122,5 +122,14 @@ interface SQL_Interface {
 	 */
 	public function column_list($table);
 
+	/**
+	 * Get the list of foreign keys for the current
+	 * table
+	 *
+	 * @parma string $table
+	 * @return string
+	 */
+	public function fk_list($table);
+
 }
 // End of sql_interface.php

drivers/firebird/firebird_sql.php

@@ -269,5 +269,35 @@ SQL;
 SQL;
 	}
 
+	// --------------------------------------------------------------------------
+
+	/**
+	 * Get the list of foreign keys for the current
+	 * table
+	 *
+	 * @parma string $table
+	 * @return string
+	 */
+	public function fk_list($table)
+	{
+		return <<<SQL
+		SELECT DISTINCT
+			rc.RDB\$CONSTRAINT_NAME AS "constraint_name",
+			rc.RDB\$RELATION_NAME AS "on table",
+			d1.RDB\$FIELD_NAME AS "on field",
+			d2.RDB\$DEPENDED_ON_NAME AS "references table",
+			d2.RDB\$FIELD_NAME AS "references field",
+			refc.RDB\$UPDATE_RULE AS "on update",
+			refc.RDB\$DELETE_RULE AS "on delete"
+		FROM RDB\$RELATION_CONSTRAINTS AS rc
+		LEFT JOIN RDB\$REF_CONSTRAINTS refc ON rc.RDB\$CONSTRAINT_NAME = refc.RDB\$CONSTRAINT_NAME
+		LEFT JOIN RDB\$DEPENDENCIES d1 ON d1.RDB\$DEPENDED_ON_NAME = rc.RDB\$RELATION_NAME
+		LEFT JOIN RDB\$DEPENDENCIES d2 ON d1.RDB\$DEPENDENT_NAME = d2.RDB\$DEPENDENT_NAME
+		WHERE rc.RDB\$CONSTRAINT_TYPE = 'FOREIGN KEY'
+			AND d1.RDB\$DEPENDED_ON_NAME <> d2.RDB\$DEPENDED_ON_NAME
+			AND d1.RDB\$FIELD_NAME <> d2.RDB\$FIELD_NAME
+			AND rc.RDB\$RELATION_NAME = '{$table}'  -- table name
+SQL;
+	}
 }
 //End of firebird_sql.php

drivers/mysql/mysql_sql.php

@@ -190,5 +190,24 @@ class MySQL_SQL extends Abstract_SQL {
 	{
 		return "SHOW FULL COLUMNS FROM {$table}";
 	}
+
+	// --------------------------------------------------------------------------
+
+	/**
+	 * Get the list of foreign keys for the current
+	 * table
+	 *
+	 * @parma string $table
+	 * @return string
+	 */
+	public function fk_list($table)
+	{
+		return <<<SQL
+			SELECT `TABLE_NAME`,`COLUMN_NAME`,`CONSTRAINT_NAME`,
+			`REFERENCED_TABLE_NAME`,`REFERENCED_COLUMN_NAME`
+			FROM `INFORMATION_SCHEMA`.`KEY_COLUMN_USAGE`
+			WHERE `REFERENCED_TABLE_NAME` = '{$table}';
+SQL;
+	}
 }
 //End of mysql_sql.php

drivers/pgsql/pgsql_sql.php

@@ -219,5 +219,46 @@ SQL;
 			ORDER BY "typname"
 SQL;
 	}
+
+	// --------------------------------------------------------------------------
+
+	/**
+	 * Get the list of foreign keys for the current
+	 * table
+	 *
+	 * @parma string $table
+	 * @return string
+	 */
+	public function fk_list($table)
+	{
+		return <<<SQL
+		SELECT
+			"att2"."attname" AS "child_column",
+			"cl"."relname" AS "parent_table",
+			"att"."attname" AS "parent_column"
+		FROM
+			(SELECT
+				unnest(con1.conkey) AS "parent",
+				unnest(con1.confkey) AS "child",
+				"con1"."confrelid",
+				"con1"."conrelid"
+			FROM "pg_class" "cl"
+			JOIN "pg_namespace" "ns" ON "cl"."relnamespace" = "ns"."oid"
+			JOIN "pg_constraint" "con1" ON "con1"."conrelid" = "cl"."oid"
+			WHERE "cl"."relname" = 'child_table'
+				AND "ns"."nspname" = 'child_schema'
+				AND "con1"."contype" = 'f'
+			)
+			"con"
+			JOIN "pg_attribute" "att" ON
+				"att"."attrelid" = "con"."confrelid"
+					AND "att"."attnum" = "con"."child"
+			JOIN "pg_class" "cl" ON
+				"cl"."oid" = "con"."confrelid"
+			JOIN "pg_attribute" "att2" ON
+			   "att2"."attrelid" = "con"."conrelid"
+				   AND "att2"."attnum" = "con"."parent"
+SQL;
 	}
-//End of pgsql_manip.php
+}
+//End of pgsql_sql.php

drivers/sqlite/sqlite_sql.php

@@ -174,5 +174,19 @@ SQL;
 		return 'PRAGMA table_info("'.$table.'")';
 	}
 
+	// --------------------------------------------------------------------------
+
+	/**
+	 * Get the list of foreign keys for the current
+	 * table
+	 *
+	 * @parma string $table
+	 * @return string
+	 */
+	public function fk_list($table)
+	{
+		return NULL;
+	}
+
 }
 //End of sqlite_sql.php

tests/core/db_test.php

@@ -75,5 +75,13 @@ abstract class DBTest extends Query_TestCase {
 		$this->assertTrue(is_array($types));
 	}
 
+	// --------------------------------------------------------------------------
+
+	public function testGetFKs()
+	{
+		$keys = $this->db->get_fks('create_test');
+		$this->assertTrue(is_array($keys));
+	}
+
 }
 // End of db_test.php

tests/databases/sqlite/SqliteTest.php

@@ -261,7 +261,16 @@ SQL;
 
 		$sql = $this->db->sql->sequence_list();
 		$this->assertEqual(NULL, $sql);
+
+		$sql = $this->db->sql->fk_list('create_test');
+		$this->assertEqual(NULL, $sql);
 	}
 
+	// --------------------------------------------------------------------------
 
+	public function testGetFKs()
+	{
+		$keys = $this->db->get_fks('create_test');
+		$this->assertNull($keys);
+	}
 }