Concurrency control problems in centralized Database Management Systems have been actively studied in past two decades. Various types of concurrency control mechanisms have been proposed and implemented in practice. Among these mechanisms, Two-Phase Locking, Timestamping and Optimistic mechanisms have attracted most attention. This thesis presents a survey on these three mechanisms, identifies their major problems and ways to resolve these problems. Despite their popularity, literatures published to date on these three mechanisms are mostly theoretical in nature, discussions on their implementation issues are normally neglected. This thesis attempts to look into this aspect by investigating the use of concurrent programming techniques based on semaphore and monitor in their implementations. Detailed descriptions of the implemenations are given and various modifications to the concurrent programming techniques to improve their applicability in the DBMS environment are provided too.