database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-07 00:36:50 +03:00
Code Activity

Rearrange and consolidate the Admin Guide.

Browse Source 
Add reference pages for utilities and remove standalone chapters for same.
Add material for an appendix on date/time properties, but not yet
 integrated with the User's Guide.
Break up the former chapter on pg_options
 into Admin and Programmer's Guides.
This commit is contained in:
Thomas G. Lockhart
1999-05-20 05:39:29 +00:00
parent c3a4d8ed54
commit 32cfa65e49
18 changed files with 2107 additions and 1997 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
doc/src/sgml/sql.sgml
View File

@ -288,7 +288,7 @@ attributes are taken from. We often write a relation scheme as
<parameter>D<subscript>i</subscript></parameter>,
for each attribute
<parameter>A<subscript>i</subscript></parameter>,
1 &le; <literal>i</literal> &le; <literal>k</literal>,
1 &lt;&equal; <literal>i</literal> &lt;&equal; <literal>k</literal>,
where the values of the attributes are taken from. We often write
a relation scheme as
<literal>R(<parameter>A<subscript>1</subscript></parameter>,
@ -325,10 +325,12 @@ attributes are taken from. We often write a relation scheme as
integers. We define this by assigning a data type to each
attribute. The type of <classname>SNAME</classname> will be
<type>VARCHAR(20)</type> (this is the <acronym>SQL</acronym> type
for character strings of length &le; 20), the type of <classname>SNO</classname> will be
for character strings of length &lt;&equal; 20),
the type of <classname>SNO</classname> will be
<type>INTEGER</type>. With the assignment of a data type we also have selected
a domain for an attribute. The domain of <classname>SNAME</classname> is the set of all
character strings of length &le; 20, the domain of <classname>SNO</classname> is the set of
character strings of length &lt;&equal; 20,
the domain of <classname>SNO</classname> is the set of
all integer numbers.
</para>
</sect2>
@ -339,7 +341,7 @@ attributes are taken from. We often write a relation scheme as
Model</title>
<para>
In section <xref linkend="formal-notion" endterm="formal-notion">
In <xref linkend="formal-notion" endterm="formal-notion">
we defined the mathematical notion of
the relational model. Now we know how the data can be stored using a
relational data model but we do not know what to do with all these
@ -481,19 +483,23 @@ attributes are taken from. We often write a relation scheme as
projecting out the duplicate column.
</para>
<para id="join-example">
Let's have a look at the tables that are produced by evaluating the steps
necessary for a join.
Let the following two tables be given:
<example id="join-example">
<title>An Inner Join</title>
<programlisting>
<para>
Let's have a look at the tables that are produced by evaluating the steps
necessary for a join.
Let the following two tables be given:
<programlisting>
R A | B | C S C | D | E
---+---+--- ---+---+---
1 | 2 | 3 3 | a | b
4 | 5 | 6 6 | c | d
7 | 8 | 9
</programlisting>
</para>
</programlisting>
</para>
</example>
<para>
First we calculate the Cartesian product