A search-as-you-type system computes answers on-the-fly as a user types in a keyword query character by character. We study how to support search-as-you-type on data residing in a relational DBMS. We focus on how to support this type of search using the native database language, SQL. A main challenge is how to leverage existing database functionalities to meet the high-performance requirement to achieve an interactive speed. We study how to use auxiliary indexes stored as tables to increase search performance. We present solutions for both single-keyword queries and multikeyword queries, and develop novel techniques for fuzzy search using SQL by allowing mismatches between query keywords and answers. We present techniques to answer first-N queries and discuss how to support updates efficiently. Experiments on large, real data sets show that our techniques enable DBMS systems on a commodity computer to support search-as-you-type on tables with millions of records.