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SQL and Relational Theory, 3rd Edition by C.J. Date

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Appendix E

Summary of Recommendations

Do as I say, not as I do.

—mid 16th century English proverb

In this appendix I present for purposes of reference a brief summary of the recommendations from Chapters 1-12. 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 16)

  • Avoid the use of any SQL construct that references physical access paths such as indexes. (Page 17)

  • Don’t use table to mean a base table specifically unless your intended meaning is clear from the context. (Page 24)

  • Don’t think of views as if they were somehow different from tables. (Page 24)

  • Avoid coercions wherever possible. (Page 62)

  • Ensure that columns with the same name are of the same type. (Page 62)

  • Avoid type conversions where possible. When they can’t be avoided, do them explicitly if you can. (Page 62)

  • Don’t use PAD SPACE. (Page 64)

  • Avoid possibly nondeterministic expressions. (Page 65)

  • Don’t use “typed tables,” reference values, REF types, or any SQL construct related to these features. (Page 67)

  • If you must talk about nulls, call them nulls and not “null values.” (Page 84)

  • Don’t use the comparison operators “<”, “<=”, “>”, and “>=” on rows of degree greater than one. (Page 88)

  • 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 97, 179)

  • If two ...

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