Yunjun Gao is a professor at the College of Computer Science, Zhejiang University, China. He received a Ph.D. in computer science from Zhejiang University, China, in 2008. Prior to joining the faculty in 2010, he was a postdoctoral fellow (scientist) at Singapore Management University from 2008-2010, and a visiting scholar or research assistant at Nanyang Technological University, Simon Fraser University, and City University of Hong Kong, respectively. His primary research areas are database, big data management, and AI Interaction with DB Technology. In particular, his current research interests include Data-Driven Machine Learning, Big Graph Data Management and Mining, Geo-Social Data Processing, Data Quality, Metric and Incomplete/Uncertain Data Management, Database Usability, and Spatial and Spatio-Temporal Databases. He has published more than 100 papers in several premium/leading international journals and conferences including TODS, VLDBJ, TKDE, TOIS, SIGMOD, VLDB, ICDE, and SIGIR. He is a member of the ACM and the IEEE, and a senior member of the CCF. He is or was an associate editor of DAPD and IJSSOE, a guest editor of WWWJ, IJDSN, and DSE, and a referee/reviewer of several prestigious journals such as TODS, VLDBJ, TKDE, TMC, and TKDD. He is serving or has served as a PC co-chair, workshop co-chair, publication chair, publicity co-chair, local poster chair, program committee member, or (external) reviewer for various important international conferences such as SIGMOD, VLDB, ICDE, EDBT, CIKM, DASFAA, SIGSPATIAL GIS, APWeb, WAIM, WISE, MDM, among others. He was an awardee/recipient of the NSFC Excellent Young Scholars Program in 2015, the Best Paper Award of APWeb-WAIM 2018, the 2017 CCF Outstanding Doctoral Dissertation Award (Advisor), the 2016 Zhejiang Provincial Outstanding Master's Dissertation Award (Advisor), the First Prize of the Ministry of Education Science and Technology Progress Award (2016), the Nomination of the Best Paper of SIGMOD 2015, oneof the Best Papers of ICDE 2015, and the First Prize of Zhejiang Province Science and Technology Award (2011).Xiaoye Miao is a Postdoctoral Fellow at the Department of Computer Science, City University of Hong Kong, China. She received a Ph.D. in computer science from Zhejiang University, China in 2017 and received a B.S. from the College of Computer Science at Xi'an Jiaotong University, China, in 2012. Her research interests include Incomplete/Uncertain Data Management, Graph Data Management, Data Pricing, and Data Cleaning. She has published more than 15 papers in several premium/leading international journals and conferences including VLDBJ, TKDE, VLDB, and ICDE. She is serving or has served as an (external) reviewer for a variety of important international journals and conferences such as VLDB Journal, TKDE, Information Sciences, WWW Journal, JCST, VLDB, ICDE, DASFAA, SIGSPATIAL GIS, APWeb, WAIM, DEXA, among others.

• Preface.- Acknowledgments.- Introduction.- Handling Incomplete Data Methods.- Query Semantics on Incomplete Data.- Advanced Techniques.- Conclusions.- Bibliography.- Authors' Biographies.

Yunjun Gao is a professor at the College of Computer Science, Zhejiang University, China. He received a Ph.D. in computer science from Zhejiang University, China, in 2008. Prior to joining the faculty in 2010, he was a postdoctoral fellow (scientist) at Singapore Management University from 2008-2010, and a visiting scholar or research assistant at Nanyang Technological University, Simon Fraser University, and City University of Hong Kong, respectively. His primary research areas are database, big data management, and AI Interaction with DB Technology. In particular, his current research interests include Data-Driven Machine Learning, Big Graph Data Management and Mining, Geo-Social Data Processing, Data Quality, Metric and Incomplete/Uncertain Data Management, Database Usability, and Spatial and Spatio-Temporal Databases. He has published more than 100 papers in several premium/leading international journals and conferences including TODS, VLDBJ, TKDE, TOIS, SIGMOD, VLDB, ICDE, and SIGIR. He is a member of the ACM and the IEEE, and a senior member of the CCF. He is or was an associate editor of DAPD and IJSSOE, a guest editor of WWWJ, IJDSN, and DSE, and a referee/reviewer of several prestigious journals such as TODS, VLDBJ, TKDE, TMC, and TKDD. He is serving or has served as a PC co-chair, workshop co-chair, publication chair, publicity co-chair, local poster chair, program committee member, or (external) reviewer for various important international conferences such as SIGMOD, VLDB, ICDE, EDBT, CIKM, DASFAA, SIGSPATIAL GIS, APWeb, WAIM, WISE, MDM, among others. He was an awardee/recipient of the NSFC Excellent Young Scholars Program in 2015, the Best Paper Award of APWeb-WAIM 2018, the 2017 CCF Outstanding Doctoral Dissertation Award (Advisor), the 2016 Zhejiang Provincial Outstanding Master's Dissertation Award (Advisor), the First Prize of the Ministry of Education Science and Technology Progress Award (2016), the Nomination of the Best Paper of SIGMOD 2015, oneof the Best Papers of ICDE 2015, and the First Prize of Zhejiang Province Science and Technology Award (2011).Xiaoye Miao is a Postdoctoral Fellow at the Department of Computer Science, City University of Hong Kong, China. She received a Ph.D. in computer science from Zhejiang University, China in 2017 and received a B.S. from the College of Computer Science at Xi'an Jiaotong University, China, in 2012. Her research interests include Incomplete/Uncertain Data Management, Graph Data Management, Data Pricing, and Data Cleaning. She has published more than 15 papers in several premium/leading international journals and conferences including VLDBJ, TKDE, VLDB, and ICDE. She is serving or has served as an (external) reviewer for a variety of important international journals and conferences such as VLDB Journal, TKDE, Information Sciences, WWW Journal, JCST, VLDB, ICDE, DASFAA, SIGSPATIAL GIS, APWeb, WAIM, DEXA, among others.

• Preface.- Acknowledgments.- Introduction.- Handling Incomplete Data Methods.- Query Semantics on Incomplete Data.- Advanced Techniques.- Conclusions.- Bibliography.- Authors' Biographies.

Yunjun Gao is a professor at the College of Computer Science, Zhejiang University, China. He received a Ph.D. in computer science from Zhejiang University, China, in 2008. Prior to joining the faculty in 2010, he was a postdoctoral fellow (scientist) at Singapore Management University from 2008-2010, and a visiting scholar or research assistant at Nanyang Technological University, Simon Fraser University, and City University of Hong Kong, respectively. His primary research areas are database, big data management, and AI Interaction with DB Technology. In particular, his current research interests include Data-Driven Machine Learning, Big Graph Data Management and Mining, Geo-Social Data Processing, Data Quality, Metric and Incomplete/Uncertain Data Management, Database Usability, and Spatial and Spatio-Temporal Databases. He has published more than 100 papers in several premium/leading international journals and conferences including TODS, VLDBJ, TKDE, TOIS, SIGMOD, VLDB, ICDE, and SIGIR. He is a member of the ACM and the IEEE, and a senior member of the CCF. He is or was an associate editor of DAPD and IJSSOE, a guest editor of WWWJ, IJDSN, and DSE, and a referee/reviewer of several prestigious journals such as TODS, VLDBJ, TKDE, TMC, and TKDD. He is serving or has served as a PC co-chair, workshop co-chair, publication chair, publicity co-chair, local poster chair, program committee member, or (external) reviewer for various important international conferences such as SIGMOD, VLDB, ICDE, EDBT, CIKM, DASFAA, SIGSPATIAL GIS, APWeb, WAIM, WISE, MDM, among others. He was an awardee/recipient of the NSFC Excellent Young Scholars Program in 2015, the Best Paper Award of APWeb-WAIM 2018, the 2017 CCF Outstanding Doctoral Dissertation Award (Advisor), the 2016 Zhejiang Provincial Outstanding Master's Dissertation Award (Advisor), the First Prize of the Ministry of Education Science and Technology Progress Award (2016), the Nomination of the Best Paper of SIGMOD 2015, oneof the Best Papers of ICDE 2015, and the First Prize of Zhejiang Province Science and Technology Award (2011).Xiaoye Miao is a Postdoctoral Fellow at the Department of Computer Science, City University of Hong Kong, China. She received a Ph.D. in computer science from Zhejiang University, China in 2017 and received a B.S. from the College of Computer Science at Xi'an Jiaotong University, China, in 2012. Her research interests include Incomplete/Uncertain Data Management, Graph Data Management, Data Pricing, and Data Cleaning. She has published more than 15 papers in several premium/leading international journals and conferences including VLDBJ, TKDE, VLDB, and ICDE. She is serving or has served as an (external) reviewer for a variety of important international journals and conferences such as VLDB Journal, TKDE, Information Sciences, WWW Journal, JCST, VLDB, ICDE, DASFAA, SIGSPATIAL GIS, APWeb, WAIM, DEXA, among others.

• Preface.- Acknowledgments.- Introduction.- Handling Incomplete Data Methods.- Query Semantics on Incomplete Data.- Advanced Techniques.- Conclusions.- Bibliography.- Authors' Biographies.