diff options
Diffstat (limited to 'doc/src/sgml/advanced.sgml')
| -rw-r--r-- | doc/src/sgml/advanced.sgml | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/doc/src/sgml/advanced.sgml b/doc/src/sgml/advanced.sgml index 82e82c13457..451bcb202ec 100644 --- a/doc/src/sgml/advanced.sgml +++ b/doc/src/sgml/advanced.sgml @@ -80,18 +80,18 @@ SELECT * FROM myview; </indexterm> <para> - Recall the <classname>weather</classname> and - <classname>cities</classname> tables from <xref + Recall the <structname>weather</structname> and + <structname>cities</structname> tables from <xref linkend="tutorial-sql"/>. Consider the following problem: You want to make sure that no one can insert rows in the - <classname>weather</classname> table that do not have a matching - entry in the <classname>cities</classname> table. This is called + <structname>weather</structname> table that do not have a matching + entry in the <structname>cities</structname> table. This is called maintaining the <firstterm>referential integrity</firstterm> of your data. In simplistic database systems this would be implemented (if at all) by first looking at the - <classname>cities</classname> table to check if a matching record + <structname>cities</structname> table to check if a matching record exists, and then inserting or rejecting the new - <classname>weather</classname> records. This approach has a + <structname>weather</structname> records. This approach has a number of problems and is very inconvenient, so <productname>PostgreSQL</productname> can do this for you. </para> @@ -578,8 +578,8 @@ SELECT sum(salary) OVER w, avg(salary) OVER w </para> <para> - Let's create two tables: A table <classname>cities</classname> - and a table <classname>capitals</classname>. Naturally, capitals + Let's create two tables: A table <structname>cities</structname> + and a table <structname>capitals</structname>. Naturally, capitals are also cities, so you want some way to show the capitals implicitly when you list all cities. If you're really clever you might invent some scheme like this: @@ -625,14 +625,14 @@ CREATE TABLE capitals ( </para> <para> - In this case, a row of <classname>capitals</classname> + In this case, a row of <structname>capitals</structname> <firstterm>inherits</firstterm> all columns (<structfield>name</structfield>, <structfield>population</structfield>, and <structfield>elevation</structfield>) from its - <firstterm>parent</firstterm>, <classname>cities</classname>. The + <firstterm>parent</firstterm>, <structname>cities</structname>. The type of the column <structfield>name</structfield> is <type>text</type>, a native <productname>PostgreSQL</productname> type for variable length character strings. The - <classname>capitals</classname> table has + <structname>capitals</structname> table has an additional column, <structfield>state</structfield>, which shows its state abbreviation. In <productname>PostgreSQL</productname>, a table can inherit from @@ -685,8 +685,8 @@ SELECT name, elevation <para> Here the <literal>ONLY</literal> before <literal>cities</literal> indicates that the query should be run over only the - <classname>cities</classname> table, and not tables below - <classname>cities</classname> in the inheritance hierarchy. Many + <structname>cities</structname> table, and not tables below + <structname>cities</structname> in the inheritance hierarchy. Many of the commands that we have already discussed — <command>SELECT</command>, <command>UPDATE</command>, and <command>DELETE</command> — support this <literal>ONLY</literal> |