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Remove useless whitespace at end of lines

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Peter Eisentraut
2010-11-23 22:27:50 +02:00
parent 44475e782f
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517 changed files with 3463 additions and 3508 deletions
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doc/src/sgml/sql.sgml
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@@ -20,10 +20,10 @@
</abstract>
<para>
<acronym>SQL</acronym> has become the most popular relational query
<acronym>SQL</acronym> has become the most popular relational query
language.
The name <quote><acronym>SQL</acronym></quote> is an abbreviation for
<firstterm>Structured Query Language</firstterm>.
<firstterm>Structured Query Language</firstterm>.
In 1974 Donald Chamberlin and others defined the
language SEQUEL (<firstterm>Structured English Query
Language</firstterm>) at IBM
@@ -64,7 +64,7 @@
Database Committee X3H2 to
develop a proposal for a standard relational language. This proposal
was ratified in 1986 and consisted essentially of the IBM dialect of
<acronym>SQL</acronym>. In 1987 this <acronym>ANSI</acronym>
<acronym>SQL</acronym>. In 1987 this <acronym>ANSI</acronym>
standard was also accepted as an international
standard by the International Organization for Standardization
(<acronym>ISO</acronym>).
@@ -89,7 +89,7 @@
<acronym>SQL/92</acronym> is the version
normally meant when people refer to <quote>the <acronym>SQL</acronym>
standard</quote>. A detailed
description of <acronym>SQL/92</acronym> is given in
description of <acronym>SQL/92</acronym> is given in
<xref linkend="DATE97" endterm="DATE97">. At the time of
writing this document a new standard informally referred to
as <firstterm><acronym>SQL3</acronym></firstterm>
@@ -115,7 +115,7 @@
</para>
<para>
A <firstterm>relational database</firstterm> is a database that is
A <firstterm>relational database</firstterm> is a database that is
perceived by its
users as a <firstterm>collection of tables</firstterm> (and
nothing else but tables).
@@ -143,7 +143,7 @@
<listitem>
<para>
SELLS stores information about which part (PNO) is sold by which
supplier (SNO).
supplier (SNO).
It serves in a sense to connect the other two tables together.
</para>
</listitem>
@@ -177,7 +177,7 @@ PART: 4 | 3
<firstterm>entities</firstterm> and
SELLS can be regarded as a <firstterm>relationship</firstterm>
between a particular
part and a particular supplier.
part and a particular supplier.
</para>
<para>
@@ -230,12 +230,12 @@ D_{1}, v_{2} \in D_{2}, \ldots, v_{k} \in D_{k}$}.
...
<parameter>v<subscript>k</subscript></parameter>,
such that
<parameter>v<subscript>1</subscript></parameter> &isin;
<parameter>v<subscript>1</subscript></parameter> &isin;
<parameter>D<subscript>1</subscript></parameter>,
<parameter>v<subscript>2</subscript></parameter> &isin;
<parameter>v<subscript>2</subscript></parameter> &isin;
<parameter>D<subscript>2</subscript></parameter>,
...
<parameter>v<subscript>k</subscript></parameter> &isin;
<parameter>v<subscript>k</subscript></parameter> &isin;
<parameter>D<subscript>k</subscript></parameter>.
</para>
@@ -293,7 +293,7 @@ domains: $R \subseteq$ \mbox{$D_{1} \times D_{2} \times \ldots \times D_{k}$}
<xref linkend="supplier-fig" endterm="supplier-fig"> where
every tuple is represented by a row and every column corresponds to
one component of a tuple. Giving names (called attributes) to the
columns leads to the definition of a
columns leads to the definition of a
<firstterm>relation scheme</firstterm>.
</para>
@@ -307,7 +307,7 @@ attributes are taken from. We often write a relation scheme as
\mbox{$R(A_{1},A_{2},\ldots,A_{k})$}.
\end{definition}
-->
A <firstterm>relation scheme</firstterm> <literal>R</literal> is a
A <firstterm>relation scheme</firstterm> <literal>R</literal> is a
finite set of attributes
<parameter>A<subscript>1</subscript></parameter>,
<parameter>A<subscript>2</subscript></parameter>,
@@ -416,7 +416,7 @@ attributes are taken from. We often write a relation scheme as
<para>
SELECT (&sigma;): extracts <firstterm>tuples</firstterm> from
a relation that
satisfy a given restriction. Let <parameter>R</parameter> be a
satisfy a given restriction. Let <parameter>R</parameter> be a
table that contains an attribute
<parameter>A</parameter>.
&sigma;<subscript>A=a</subscript>(R) = {t &isin; R &mid; t(A) = a}
@@ -447,7 +447,7 @@ attributes are taken from. We often write a relation scheme as
<classname>S</classname> be a table with
arity <literal>k</literal><subscript>2</subscript>.
<classname>R</classname> &times; <classname>S</classname>
is the set of all
is the set of all
<literal>k</literal><subscript>1</subscript>
+ <literal>k</literal><subscript>2</subscript>-tuples
whose first <literal>k</literal><subscript>1</subscript>
@@ -477,7 +477,7 @@ attributes are taken from. We often write a relation scheme as
set of tuples
that are in <classname>R</classname> and in
<classname>S</classname>.
We again require that <classname>R</classname> and
We again require that <classname>R</classname> and
<classname>S</classname> have the
same arity.
</para>
@@ -497,14 +497,14 @@ attributes are taken from. We often write a relation scheme as
<listitem>
<para>
JOIN (&prod;): connects two tables by their common
attributes. Let <classname>R</classname> be a table with the
attributes <classname>A</classname>,<classname>B</classname>
attributes. Let <classname>R</classname> be a table with the
attributes <classname>A</classname>,<classname>B</classname>
and <classname>C</classname> and
let <classname>S</classname> be a table with the attributes
<classname>C</classname>,<classname>D</classname>
and <classname>E</classname>. There is one
attribute common to both relations,
the attribute <classname>C</classname>.
the attribute <classname>C</classname>.
<!--
<classname>R</classname> &prod; <classname>S</classname> =
&pi;<subscript><classname>R</classname>.<classname>A</classname>,<classname>R</classname>.<classname>B</classname>,<classname>R</classname>.<classname>C</classname>,<classname>S</classname>.<classname>D</classname>,<classname>S</classname>.<classname>E</classname></subscript>(&sigma;<subscript><classname>R</classname>.<classname>C</classname>=<classname>S</classname>.<classname>C</classname></subscript>(<classname>R</classname> &times; <classname>S</classname>)).
@@ -651,11 +651,11 @@ R: S:
<title id="suppl-rel-alg">A Query Using Relational Algebra</title>
<para>
Recall that we formulated all those relational operators to be able to
retrieve data from the database. Let's return to our example from
retrieve data from the database. Let's return to our example from
the previous
section (<xref linkend="operations" endterm="operations">)
where someone wanted to know the names of all
suppliers that sell the part <literal>Screw</literal>.
suppliers that sell the part <literal>Screw</literal>.
This question can be answered
using relational algebra by the following operation:
@@ -762,7 +762,7 @@ x(A) &mid; F(x)
<para>
The relational algebra and the relational calculus have the same
<firstterm>expressive power</firstterm>; i.e., all queries that
can be formulated using relational algebra can also be formulated
can be formulated using relational algebra can also be formulated
using the relational calculus and vice versa.
This was first proved by E. F. Codd in
1972. This proof is based on an algorithm (<quote>Codd's reduction
@@ -835,7 +835,7 @@ A &lt; B + 3.
<para>
Aggregate Functions: Operations such as
<firstterm>average</firstterm>, <firstterm>sum</firstterm>,
<firstterm>max</firstterm>, etc. can be applied to columns of a
<firstterm>max</firstterm>, etc. can be applied to columns of a
relation to
obtain a single quantity.
</para>
@@ -908,7 +908,7 @@ SELECT * FROM PART
statement:
<programlisting>
SELECT PNAME, PRICE
SELECT PNAME, PRICE
FROM PART
WHERE PRICE &gt; 10;
</programlisting>
@@ -933,7 +933,7 @@ SELECT PNAME, PRICE
using the keywords OR, AND, and NOT:
<programlisting>
SELECT PNAME, PRICE
SELECT PNAME, PRICE
FROM PART
WHERE PNAME = 'Bolt' AND
(PRICE = 0 OR PRICE &lt;= 15);
@@ -1020,7 +1020,7 @@ SELECT S.SNAME, P.PNAME
because there are common named attributes (SNO and PNO) among the
relations. Now we can distinguish between the common named attributes
by simply prefixing the attribute name with the alias name followed by
a dot. The join is calculated in the same way as shown in
a dot. The join is calculated in the same way as shown in
<xref linkend="join-example" endterm="join-example">.
First the Cartesian product
@@ -1029,7 +1029,7 @@ SELECT S.SNAME, P.PNAME
is derived. Now only those tuples satisfying the
conditions given in the WHERE clause are selected (i.e., the common
named attributes have to be equal). Finally we project out all
columns but S.SNAME and P.PNAME.
columns but S.SNAME and P.PNAME.
</para>
<para>
@@ -1051,7 +1051,7 @@ SELECT sname, pname from supplier
Blake | Bolt
Jones | Cam
Blake | Cam
(8 rows)
(8 rows)
</screen>
</para>
@@ -1148,7 +1148,7 @@ SELECT sname, pname from supplier
<listitem>
<para>
For each row R1 of T1, the joined table has a row for each row
in T2 that satisfies the join condition with R1.
in T2 that satisfies the join condition with R1.
</para>
<tip>
<para>
@@ -1322,11 +1322,11 @@ SELECT COUNT(PNO)
The partitioning of the tuples into groups is done by using the
keywords <command>GROUP BY</command> followed by a list of
attributes that define the
groups. If we have
groups. If we have
<command>GROUP BY A<subscript>1</subscript>, &tdot;, A<subscript>k</subscript></command>
we partition
the relation into groups, such that two tuples are in the same group
if and only if they agree on all the attributes
if and only if they agree on all the attributes
A<subscript>1</subscript>, &tdot;, A<subscript>k</subscript>.
<example>
@@ -1482,8 +1482,8 @@ SELECT S.SNO, S.SNAME, COUNT(SE.PNO)
named 'Screw' we use the query:
<programlisting>
SELECT *
FROM PART
SELECT *
FROM PART
WHERE PRICE &gt; (SELECT PRICE FROM PART
WHERE PNAME='Screw');
</programlisting>
@@ -1516,11 +1516,11 @@ SELECT *
</para>
<para>
If we want to know all suppliers that do not sell any part
If we want to know all suppliers that do not sell any part
(e.g., to be able to remove these suppliers from the database) we use:
<programlisting>
SELECT *
SELECT *
FROM SUPPLIER S
WHERE NOT EXISTS
(SELECT * FROM SELLS SE
@@ -1595,7 +1595,7 @@ SELECT S.SNO, S.SNAME, S.CITY
UNION
SELECT S.SNO, S.SNAME, S.CITY
FROM SUPPLIER S
WHERE S.SNAME = 'Adams';
WHERE S.SNAME = 'Adams';
</programlisting>
gives the result:
@@ -1664,7 +1664,7 @@ EXCEPT
<para>
There is a set of commands used for data definition included in the
<acronym>SQL</acronym> language.
<acronym>SQL</acronym> language.
</para>
<sect3 id="create">
@@ -1678,7 +1678,7 @@ EXCEPT
<synopsis>
CREATE TABLE <replaceable class="parameter">table_name</replaceable>
(<replaceable class="parameter">name_of_attr_1</replaceable> <replaceable class="parameter">type_of_attr_1</replaceable>
[, <replaceable class="parameter">name_of_attr_2</replaceable> <replaceable class="parameter">type_of_attr_2</replaceable>
[, <replaceable class="parameter">name_of_attr_2</replaceable> <replaceable class="parameter">type_of_attr_2</replaceable>
[, ...]]);
</synopsis>
@@ -1718,7 +1718,7 @@ CREATE TABLE SELLS
<title>Data Types in <acronym>SQL</acronym></title>
<para>
The following is a list of some data types that are supported by
The following is a list of some data types that are supported by
<acronym>SQL</acronym>:
<itemizedlist>
@@ -1792,7 +1792,7 @@ CREATE TABLE SELLS
the <command>CREATE INDEX</command> command is used. The syntax is:
<programlisting>
CREATE INDEX <replaceable class="parameter">index_name</replaceable>
CREATE INDEX <replaceable class="parameter">index_name</replaceable>
ON <replaceable class="parameter">table_name</replaceable> ( <replaceable class="parameter">name_of_attribute</replaceable> );
</programlisting>
</para>
@@ -1860,11 +1860,11 @@ CREATE VIEW <replaceable class="parameter">view_name</replaceable>
AS <replaceable class="parameter">select_stmt</replaceable>
</programlisting>
where <replaceable class="parameter">select_stmt</replaceable>
where <replaceable class="parameter">select_stmt</replaceable>
is a valid select statement as defined
in <xref linkend="select-title" endterm="select-title">.
Note that <replaceable class="parameter">select_stmt</replaceable> is
not executed when the view is created. It is just stored in the
not executed when the view is created. It is just stored in the
<firstterm>system catalogs</firstterm>
and is executed whenever a query against the view is made.
</para>
@@ -1967,7 +1967,7 @@ DROP VIEW <replaceable class="parameter">view_name</replaceable>;
The syntax is:
<programlisting>
INSERT INTO <replaceable class="parameter">table_name</replaceable> (<replaceable class="parameter">name_of_attr_1</replaceable>
INSERT INTO <replaceable class="parameter">table_name</replaceable> (<replaceable class="parameter">name_of_attr_1</replaceable>
[, <replaceable class="parameter">name_of_attr_2</replaceable> [,...]])
VALUES (<replaceable class="parameter">val_attr_1</replaceable> [, <replaceable class="parameter">val_attr_2</replaceable> [, ...]]);
</programlisting>
@@ -2003,7 +2003,7 @@ INSERT INTO SELLS (SNO, PNO)
<programlisting>
UPDATE <replaceable class="parameter">table_name</replaceable>
SET <replaceable class="parameter">name_of_attr_1</replaceable> = <replaceable class="parameter">value_1</replaceable>
SET <replaceable class="parameter">name_of_attr_1</replaceable> = <replaceable class="parameter">value_1</replaceable>
[, ... [, <replaceable class="parameter">name_of_attr_k</replaceable> = <replaceable class="parameter">value_k</replaceable>]]
WHERE <replaceable class="parameter">condition</replaceable>;
</programlisting>
@@ -2120,7 +2120,7 @@ DELETE FROM SUPPLIER
by a <firstterm>precompiler</firstterm>
(which usually inserts
calls to library routines that perform the various <acronym>SQL</acronym>
commands).
commands).
</para>
<para>