Resolve formatting differences between DB forge drivers
diff --git a/system/database/drivers/interbase/interbase_forge.php b/system/database/drivers/interbase/interbase_forge.php
index 5470179..166f387 100644
--- a/system/database/drivers/interbase/interbase_forge.php
+++ b/system/database/drivers/interbase/interbase_forge.php
@@ -87,7 +87,7 @@
 	{
 		$sql = 'CREATE TABLE ';
 
-		$sql .= $this->db->protect_identifiers($table)."(";
+		$sql .= $this->db->protect_identifiers($table).'(';
 		$current_field_count = 0;
 
 		foreach ($fields as $field => $attributes)
@@ -97,41 +97,30 @@
 			// entered the field information, so we'll simply add it to the list
 			if (is_numeric($field))
 			{
-				$sql .= "\n\t$attributes";
+				$sql .= "\n\t".$attributes;
 			}
 			else
 			{
 				$attributes = array_change_key_case($attributes, CASE_UPPER);
 
-				$sql .= "\n\t".$this->db->protect_identifiers($field);
+				$sql .= "\n\t".$this->db->escape_identifiers($field).' '.$attributes['TYPE'];
 
-				$sql .=  ' '.$attributes['TYPE'];
+				empty($attributes['CONSTRAINT']) OR $sql .= '('.$attributes['CONSTRAINT'].')';
 
-				if (array_key_exists('CONSTRAINT', $attributes))
-				{
-					$sql .= '('.$attributes['CONSTRAINT'].')';
-				}
-
-				if (array_key_exists('UNSIGNED', $attributes) && $attributes['UNSIGNED'] === TRUE)
+				if ( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE)
 				{
 					$sql .= ' UNSIGNED';
 				}
 
-				if (array_key_exists('DEFAULT', $attributes))
+				if (isset($attributes['DEFAULT']))
 				{
-					$sql .= ' DEFAULT \''.$attributes['DEFAULT'].'\'';
+					$sql .= " DEFAULT '".$attributes['DEFAULT']."'";
 				}
 
-				if (array_key_exists('NULL', $attributes) && $attributes['NULL'] === TRUE)
-				{
-					$sql .= ' NULL';
-				}
-				else
-				{
-					$sql .= ' NOT NULL';
-				}
+				$sql .= ( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE)
+					? ' NULL' : ' NOT NULL';
 
-				if (array_key_exists('AUTO_INCREMENT', $attributes) && $attributes['AUTO_INCREMENT'] === TRUE)
+				if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
 				{
 					$sql .= ' AUTO_INCREMENT';
 				}
@@ -146,30 +135,23 @@
 
 		if (count($primary_keys) > 0)
 		{
-			$primary_keys = $this->db->protect_identifiers($primary_keys);
-			$sql .= ",\n\tPRIMARY KEY (" . implode(', ', $primary_keys) . ")";
+			$primary_keys = $this->db->escape_identifiers($primary_keys);
+			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $primary_keys).')';
 		}
 
 		if (is_array($keys) && count($keys) > 0)
 		{
 			foreach ($keys as $key)
 			{
-				if (is_array($key))
-				{
-					$key = $this->db->protect_identifiers($key);
-				}
-				else
-				{
-					$key = array($this->db->protect_identifiers($key));
-				}
+				$key = is_array($key)
+					? $this->db->escape_identifiers($key)
+					: array($this->db->escape_identifiers($key));
 
-				$sql .= ",\n\tUNIQUE (" . implode(', ', $key) . ")";
+				$sql .= ",\n\tUNIQUE (".implode(', ', $key).')';
 			}
 		}
 
-		$sql .= "\n)";
-
-		return $sql;
+		return $sql."\n)";
 	}
 
 	// --------------------------------------------------------------------
@@ -191,31 +173,11 @@
 	 */
 	protected function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
 	{
-		$sql = 'ALTER TABLE '.$this->db->protect_identifiers($table)." $alter_type ".$this->db->protect_identifiers($column_name);
-
-		$sql .= " {$column_definition}";
-
-		if ($default_value !== '')
-		{
-			$sql .= " DEFAULT \"{$default_value}\"";
-		}
-
-		if ($null === NULL)
-		{
-			$sql .= ' NULL';
-		}
-		else
-		{
-			$sql .= ' NOT NULL';
-		}
-
-		if ($after_field !== '')
-		{
-			$sql .= ' AFTER ' . $this->db->protect_identifiers($after_field);
-		}
-
-		return $sql;
-
+		return 'ALTER TABLE '.$this->db->escape_identifiers($table).' '.$alter_type.' '.$this->db->escape_identifiers($column_name)
+			.' '.$column_definition
+			.($default_value !== '' ? ' DEFAULT "'.$default_value.'"' : '')
+			.($null === NULL ? ' NULL' : ' NOT NULL')
+			.($after_field !== '' ? ' AFTER '.$this->db->escape_identifiers($after_field) : '');
 	}
 
 }