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Update documentation on may/can/might:

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Standard English uses "may", "can", and "might" in different ways:

        may - permission, "You may borrow my rake."

        can - ability, "I can lift that log."

        might - possibility, "It might rain today."

Unfortunately, in conversational English, their use is often mixed, as
in, "You may use this variable to do X", when in fact, "can" is a better
choice.  Similarly, "It may crash" is better stated, "It might crash".

Also update two error messages mentioned in the documenation to match.
This commit is contained in:
Bruce Momjian
2007-01-31 20:56:20 +00:00
parent 67a1ae9f05
commit a134ee3379
70 changed files with 729 additions and 731 deletions
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28
doc/src/sgml/queries.sgml
View File

@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/queries.sgml,v 1.41 2007/01/09 16:59:20 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/queries.sgml,v 1.42 2007/01/31 20:56:18 momjian Exp $ -->
<chapter id="queries">
<title>Queries</title>
@@ -116,11 +116,11 @@ SELECT random();
FROM <replaceable>table_reference</replaceable> <optional>, <replaceable>table_reference</replaceable> <optional>, ...</optional></optional>
</synopsis>
A table reference may be a table name (possibly schema-qualified),
A table reference can be a table name (possibly schema-qualified),
or a derived table such as a subquery, a table join, or complex
combinations of these. If more than one table reference is listed
in the <literal>FROM</> clause they are cross-joined (see below)
to form the intermediate virtual table that may then be subject to
to form the intermediate virtual table that can then be subject to
transformations by the <literal>WHERE</>, <literal>GROUP BY</>,
and <literal>HAVING</> clauses and is finally the result of the
overall table expression.
@@ -350,8 +350,8 @@ FROM <replaceable>table_reference</replaceable> <optional>, <replaceable>table_r
<para>
Joins of all types can be chained together or nested: either or
both of <replaceable>T1</replaceable> and
<replaceable>T2</replaceable> may be joined tables. Parentheses
may be used around <literal>JOIN</> clauses to control the join
<replaceable>T2</replaceable> might be joined tables. Parentheses
can be used around <literal>JOIN</> clauses to control the join
order. In the absence of parentheses, <literal>JOIN</> clauses
nest left-to-right.
</para>
@@ -623,7 +623,7 @@ FROM (VALUES ('anne', 'smith'), ('bob', 'jones'), ('joe', 'blow'))
of either base data types (scalar types) or composite data types
(table rows). They are used like a table, view, or subquery in
the <literal>FROM</> clause of a query. Columns returned by table
functions may be included in <literal>SELECT</>,
functions can be included in <literal>SELECT</>,
<literal>JOIN</>, or <literal>WHERE</> clauses in the same manner
as a table, view, or subquery column.
</para>
@@ -636,8 +636,8 @@ FROM (VALUES ('anne', 'smith'), ('bob', 'jones'), ('joe', 'blow'))
</para>
<para>
A table function may be aliased in the <literal>FROM</> clause,
but it also may be left unaliased. If a function is used in the
A table function can be aliased in the <literal>FROM</> clause,
but it also can be left unaliased. If a function is used in the
<literal>FROM</> clause with no alias, the function name is used
as the resulting table name.
</para>
@@ -788,7 +788,7 @@ SELECT ... FROM fdt WHERE EXISTS (SELECT c1 FROM t2 WHERE c2 &gt; fdt.c1)
<para>
After passing the <literal>WHERE</> filter, the derived input
table may be subject to grouping, using the <literal>GROUP BY</>
table might be subject to grouping, using the <literal>GROUP BY</>
clause, and elimination of group rows using the <literal>HAVING</>
clause.
</para>
@@ -877,7 +877,7 @@ SELECT product_id, p.name, (sum(s.units) * p.price) AS sales
<literal>p.name</literal>, and <literal>p.price</literal> must be
in the <literal>GROUP BY</> clause since they are referenced in
the query select list. (Depending on how exactly the products
table is set up, name and price may be fully dependent on the
table is set up, name and price might be fully dependent on the
product ID, so the additional groupings could theoretically be
unnecessary, but this is not implemented yet.) The column
<literal>s.units</> does not have to be in the <literal>GROUP
@@ -1070,7 +1070,7 @@ SELECT a AS value, b + c AS sum FROM ...
</indexterm>
<para>
After the select list has been processed, the result table may
After the select list has been processed, the result table can
optionally be subject to the elimination of duplicate rows. The
<literal>DISTINCT</literal> key word is written directly after
<literal>SELECT</literal> to specify this:
@@ -1234,7 +1234,7 @@ SELECT a, b FROM table1 ORDER BY a + b, c;
</programlisting>
When more than one expression is specified,
the later values are used to sort rows that are equal according to the
earlier values. Each expression may be followed by an optional
earlier values. Each expression can be followed by an optional
<literal>ASC</> or <literal>DESC</> keyword to set the sort direction to
ascending or descending. <literal>ASC</> order is the default.
Ascending order puts smaller values first, where
@@ -1342,7 +1342,7 @@ SELECT <replaceable>select_list</replaceable>
When using <literal>LIMIT</>, it is important to use an
<literal>ORDER BY</> clause that constrains the result rows into a
unique order. Otherwise you will get an unpredictable subset of
the query's rows. You may be asking for the tenth through
the query's rows. You might be asking for the tenth through
twentieth rows, but tenth through twentieth in what ordering? The
ordering is unknown, unless you specified <literal>ORDER BY</>.
</para>
@@ -1364,7 +1364,7 @@ SELECT <replaceable>select_list</replaceable>
<para>
The rows skipped by an <literal>OFFSET</> clause still have to be
computed inside the server; therefore a large <literal>OFFSET</>
can be inefficient.
might be inefficient.
</para>
</sect1>