DNA has been considered as a compelling candidate for digital data storage due to advantages such as high coding density, long retention time, and low energy consumption. Despite many works reported, the development of a DNA-based database of full integration, high efficiency, and practical applicability is still challenging. In this work, we report the synthesis and sequencing of DNA on a single electrode with scalability for an integrated DNA-based data storage system. The synthesis of DNA is based on phosphoramidite chemistry and electrochemical deprotection. The sequencing relies on charge redistribution originated from polymerase-catalyzed primer extension, leading to a measurable current spike. By regeneration of the electrode after sequencing, repeated sequencing can be achieved to improve the accuracy. A SlipChip device is developed to simplify the liquid introduction involved in DNA synthesis and sequencing. As the proof-of-concept experiment, text information is stored in the system and then accurately retrieved.