ABSTRACT Embedded SQL queries have become an integral part of modern web applications and many SQL complexity metrics have been proposed, but subject of validation of this metrics is still actual. In this study we are going to validate SQL complexity metrics for adaptive maintenance effort (DLOC) estimation. Obtained that instead of classic complexity characteristics, SQL complexity metrics keep a good correlation with DLOC with growing (function length)min for a small and medium source code changes. Proposed a liner regression model for estimating the mixing power of application business logic and SQL query compiling logic (SQL Mix Complexity). SELECT operators count in a combination with CCN and Halstead`s Difficulty have a good correlation with DLOC for a methods with lengths higher than 2000 symbols for a small and medium source code changes.
