SQL and Relational Theory, 2nd Edition

Appendix E. Summary of Recommendations

In this appendix I present for purposes of quick reference a brief summary of the recommendations from Chapter 1–Chapter 12. The page numbers against the various items show where the individual recommendations are discussed in the body of the text.

• Don’t use SQL like a simple access method. (Page 13)

• Avoid the use of any SQL construct that references physical access paths such as indexes. (Pages 13-14)

• Don’t use table to mean a base table specifically unless your intended meaning is clear from the context. Don’t think of views as if they were somehow different from tables. (Page 19)

• Avoid coercions wherever possible. (Page 41)

• Ensure that columns with the same name are of the same type. (Page 41)

• Avoid type conversions where possible. When they can’t be avoided, do them explicitly if you can. (Pages 41-42)

• Don’t use PAD SPACE. (Page 43)

• Avoid possibly nondeterministic expressions. (Page 43)

• Don’t use “typed tables,” reference values, REF types, or any SQL construct related to these features. (Page 45)

• If you must talk about nulls, call them nulls, not “null values.” (Page 51)

• Don’t use the comparison operators “<”, “<=”, “>”, and “>=” on rows of degree greater than one. (Page 55)

• Use AS specifications whenever necessary (and possible) to give proper column names to columns that otherwise (a) wouldn’t have a name at all or (b) would have a name that wasn’t unique. (Pages 62, 110)

• If two columns represent the same kind of information, give them the same name ...