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## Various doc errors and shortcomings

### Responses

### pgsql-bugs by date

Hello PostgreSQL! I've found several errors in the documentation. The first is a shortcoming rather than an error, but it cost me hours of needless effort. You said you welcome bug reports, so here's what I have: - - - - - Programmer's Guide, 8.2.3. Connecting to the Database According to the documentation, the URL includes what is called "the database name". I assumed that the fully qualified path name was intended here, since that is what normally appears in a URL. How else does one unambiguously identify a file? So that is what I tried, and it repeatedly resulted in cryptic "no suitable driver" messages. I thought the problem was in the Java configuration. One or two examples are needed in this section to make it clear that postgresql has its own directory of "registered" databases, and the "database name" in question is the name in this registry, not the database filename. - - - - - Tutorial Chapter 2: In the following "&cup" is erroneously used to represent intersection: Relational Algebra INTERSECT (∩): builds the set-theoretic intersection of two tables. Given the tables R and S, R ∪ S is the set of tuples that are in R and in S. We again require that R and S have the same arity. - - - - - Tutorial Chapter 2: What does the "\nonumber" signify in the following? Tuple Relational Calculus The queries used in TRC are of the following form: x(A) ∣ F(x) where x is a tuple variable A is a set of attributes and F is a formula. The resulting relation consists of all tuples t(A) that satisfy F(t). If we want to answer the question from example A Query Using Relational Algebra using TRC we formulate the following query: {x(SNAME) ∣ x ∈ SUPPLIER ∧ \nonumber ∃ y ∈ SELLS ∃ z ∈ PART (y(SNO)=x(SNO) ∧ \nonumber z(PNO)=y(PNO) ∧ \nonumber z(PNAME)='Screw')} \nonumber Evaluating the query against the tables from The Suppliers and Parts Database again leads to the same result as in A Query Using Relational Algebra. - - - - - Tutorial Chapter 2: In the following, the condition should be "PRICE <= 15" Example 2-4. Simple Query with Qualification The qualifications in the WHERE clause can also be logically connected using the keywords OR, AND, and NOT: SELECT PNAME, PRICE FROM PART WHERE PNAME = 'Bolt' AND (PRICE = 0 OR PRICE < 15); will lead to the result: PNAME | PRICE --------+-------- Bolt | 15 - - - - - Tutorial Chapter 2: The following example seems incorrect. In S.SNO is greater than 2, then S.SNO is also greater than 1, so the intersection should include suppliers 2, 3, 4, etc.. Here an example for INTERSECT: SELECT S.SNO, S.SNAME, S.CITY FROM SUPPLIER S WHERE S.SNO > 1 INTERSECT SELECT S.SNO, S.SNAME, S.CITY FROM SUPPLIER S WHERE S.SNO > 2; gives the result: SNO | SNAME | CITY -----+-------+-------- 2 | Jones | Paris The only tuple returned by both parts of the query is the one having $SNO=2$. - - - - -

- Re: Various doc errors and shortcomings at 2001-08-20 15:53:39 from Peter Eisentraut

Next: From:Truong, LongDate:2001-08-16 12:02:53Subject: openVMS 7.2Previous: From: Peter EisentrautDate: 2001-08-15 15:50:14Subject: Re: -ltermcap needed for psql client build on OpenBSD 2.9