USER ERRORS IN DATABASE QUERY COMPOSITION

This research reports on the experimental test of several causes of us er errors while composing database queries. The query language under c onsideration is Structured Query Language (SQL), the industry standard language for querying databases. Unfortunately, users commit many err ors when using SQL. To understand user errors, a model of query writin g was developed that integrated a GOMS-type analysis of query writing with the characteristics of human cognition. This model revealed multi ple cognitive causes of a frequent and troublesome error, join clause omission. This semantic user error returns answers from the database t hat may be undetectably wrong, affecting users, decision makers, and p rogrammers. The model predicted four possible causes of join clause om ission, and empirical testing revealed that all four contributed to th e error. Specifically, the frequency of this error increased because ( 1) the load on working memory caused by writing intervening clauses ma de the users forget to include the join clause, (2) an explicit clue t o write the join clause was absent from the problem statement, (3) use rs inappropriately reused the procedure appropriate for a single table query, which requires no join clause, when a join clause is indeed ne cessary, and (4) some users never learned the comet procedure. These r esults are significant for understanding user errors in general and fo r developing new interfaces and training schemes for the task of writi ng database queries.