This volume contains the proceedings of the 12th International Symposium on Database Programming Languages (DBPL 2009), held in Lyon, France on - gust 24, 2009, and co-locatedwith VLDB (the International Conference on Very Large Data Bases). DBPL continues to present high-quality work at the intersection of database and programming language research. This proceedings volume contains the six papersacceptedforDBPL2009, whichwereselectedbytheProgramCommittee. Every submission was reviewed by at least three members of the committee. In addition, we sought the opinions of external referees, chosen...

Data quality is one of the most important problems in data management. A database system typically aims to support the creation, maintenance, and use of large amount of data, focusing on the quantity of data. However, real-life data are often dirty: inconsistent, duplicated, inaccurate, incomplete, or stale. Dirty data in a database routinely generate misleading or biased analytical results and decisions, and lead to loss of revenues, credibility and customers. With this comes the need for data quality management. In contrast to traditional data management tasks, data quality management...