diff options
Diffstat (limited to 'doc/src/sgml/query.sgml')
| -rw-r--r-- | doc/src/sgml/query.sgml | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/doc/src/sgml/query.sgml b/doc/src/sgml/query.sgml index ffc641b03ad..c81c321134b 100644 --- a/doc/src/sgml/query.sgml +++ b/doc/src/sgml/query.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/query.sgml,v 1.51 2008/12/28 18:53:54 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/query.sgml,v 1.52 2009/04/27 16:27:36 momjian Exp $ --> <chapter id="tutorial-sql"> <title>The <acronym>SQL</acronym> Language</title> @@ -38,7 +38,7 @@ functions and types. (If you installed a pre-packaged version of <productname>PostgreSQL</productname> rather than building from source, look for a directory named <filename>tutorial</> within the - <productname>PostgreSQL</productname> documentation. The <quote>make</> + <productname>PostgreSQL</productname> distribution. The <quote>make</> part should already have been done for you.) Then, to start the tutorial, do the following: @@ -53,7 +53,7 @@ </screen> The <literal>\i</literal> command reads in commands from the - specified file. The <literal>-s</literal> option puts you in + specified file. The <command>psql</command> <literal>-s</> option puts you in single step mode which pauses before sending each statement to the server. The commands used in this section are in the file <filename>basics.sql</filename>. @@ -165,7 +165,7 @@ CREATE TABLE weather ( and a rich set of geometric types. <productname>PostgreSQL</productname> can be customized with an arbitrary number of user-defined data types. Consequently, type - names are not syntactical key words, except where required to + names are not special key words in the syntax except where required to support special cases in the <acronym>SQL</acronym> standard. </para> @@ -421,7 +421,7 @@ SELECT DISTINCT city <literal>DISTINCT</literal> automatically orders the rows and so <literal>ORDER BY</literal> is unnecessary. But this is not required by the SQL standard, and current - <productname>PostgreSQL</productname> doesn't guarantee that + <productname>PostgreSQL</productname> does not guarantee that <literal>DISTINCT</literal> causes the rows to be ordered. </para> </footnote> @@ -451,8 +451,8 @@ SELECT DISTINCT city <firstterm>join</firstterm> query. As an example, say you wish to list all the weather records together with the location of the associated city. To do that, we need to compare the city column of - each row of the weather table with the name column of all rows in - the cities table, and select the pairs of rows where these values match. + each row of the <literal>weather</> table with the name column of all rows in + the <literal>cities</> table, and select the pairs of rows where these values match. <note> <para> This is only a conceptual model. The join is usually performed @@ -486,7 +486,7 @@ SELECT * There is no result row for the city of Hayward. This is because there is no matching entry in the <classname>cities</classname> table for Hayward, so the join - ignores the unmatched rows in the weather table. We will see + ignores the unmatched rows in the <literal>weather</> table. We will see shortly how this can be fixed. </para> </listitem> @@ -494,9 +494,9 @@ SELECT * <listitem> <para> There are two columns containing the city name. This is - correct because the lists of columns of the + correct because the columns from the <classname>weather</classname> and the - <classname>cities</classname> table are concatenated. In + <classname>cities</classname> tables are concatenated. In practice this is undesirable, though, so you will probably want to list the output columns explicitly rather than using <literal>*</literal>: @@ -514,14 +514,14 @@ SELECT city, temp_lo, temp_hi, prcp, date, location <title>Exercise:</title> <para> - Attempt to find out the semantics of this query when the + Attempt to determine the semantics of this query when the <literal>WHERE</literal> clause is omitted. </para> </formalpara> <para> Since the columns all had different names, the parser - automatically found out which table they belong to. If there + automatically found which table they belong to. If there were duplicate column names in the two tables you'd need to <firstterm>qualify</> the column names to show which one you meant, as in: |