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First files for reference pages.
This commit is contained in:
Thomas G. Lockhart
553
doc/src/sgml/ref/select.sgml
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553
doc/src/sgml/ref/select.sgml
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@@ -0,0 +1,553 @@
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<REFENTRY ID="SQL-SELECT-1">
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<REFMETA>
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<REFENTRYTITLE>
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SELECT
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</REFENTRYTITLE>
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<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
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</REFMETA>
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<REFNAMEDIV>
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<REFNAME>
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SELECT
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</REFNAME>
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<REFPURPOSE>
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Retrieve rows from a table or view
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</REFPURPOSE>
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<REFSYNOPSISDIV>
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<REFSYNOPSISDIVINFO>
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<DATE>1998-04-15</DATE>
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</REFSYNOPSISDIVINFO>
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<SYNOPSIS>
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<REPLACEABLE CLASS="PARAMETER">
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</REPLACEABLE>
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SELECT [ALL|DISTINCT]
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<REPLACEABLE CLASS="PARAMETER">expression</REPLACEABLE> [AS <REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE>] [, ...]
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[INTO [TABLE] <REPLACEABLE CLASS="PARAMETER">intable</REPLACEABLE>]
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[FROM <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE> [<REPLACEABLE CLASS="PARAMETER">alias</REPLACEABLE>] [, ...] ]
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[WHERE <REPLACEABLE CLASS="PARAMETER">condition</REPLACEABLE>]
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[GROUP BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [, ...] ]
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[HAVING <REPLACEABLE CLASS="PARAMETER">condition</REPLACEABLE> [, ...] ]
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[UNION [ALL] <REPLACEABLE CLASS="PARAMETER">select</REPLACEABLE>]
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[ORDER BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [ASC | DESC] [, ...] ]
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||||
</SYNOPSIS>
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||||
|
||||
<REFSECT2 ID="R2-SQL-SELECT-1">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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Inputs
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</TITLE>
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||||
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<PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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<REPLACEABLE CLASS="PARAMETER">expression</REPLACEABLE>
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</TERM>
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<LISTITEM>
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<PARA>
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The name of a table's column or an expression.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE>
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</TERM>
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<LISTITEM>
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<PARA>
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Specifies another name for a column or an expression using
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the AS clause. <REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE> cannot be used in the WHERE
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condition. It can, however, be referenced in associated
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ORDER BY or GROUP BY clauses.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<REPLACEABLE CLASS="PARAMETER">intable</REPLACEABLE>
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</TERM>
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<LISTITEM>
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<PARA>
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If the INTO TABLE clause is specified, the result of the
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query will be stored in another table with the indicated
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name.
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If <REPLACEABLE CLASS="PARAMETER">intable</REPLACEABLE> does not exist, it will be created automatically.
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<Note>
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<Para>
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The CREATE TABLE AS statement will also create a new table from a select query.
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</Para>
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</Note>
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
|
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|
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<VARLISTENTRY>
|
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<TERM>
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<REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
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</TERM>
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<LISTITEM>
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<PARA>
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The name of an existing table referenced by FROM clause.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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|
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<VARLISTENTRY>
|
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<TERM>
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<REPLACEABLE CLASS="PARAMETER">alias</REPLACEABLE>
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</TERM>
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<LISTITEM>
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<PARA>
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An alternate name for the preceeding <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>.
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Used for brevity or to eliminate ambiguity for joins within a single table.
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</PARA>
|
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</LISTITEM>
|
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</VARLISTENTRY>
|
||||
|
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<VARLISTENTRY>
|
||||
<TERM>
|
||||
<REPLACEABLE CLASS="PARAMETER">condition</REPLACEABLE>
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||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
An expression leading to a boolean (true/false) result.
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||||
See the WHERE clause.
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||||
</PARA>
|
||||
</LISTITEM>
|
||||
</VARLISTENTRY>
|
||||
|
||||
<VARLISTENTRY>
|
||||
<TERM>
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<REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE>
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</TERM>
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<LISTITEM>
|
||||
<PARA>
|
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The name of a table's column.
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||||
</PARA>
|
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</LISTITEM>
|
||||
</VARLISTENTRY>
|
||||
|
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<VARLISTENTRY>
|
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<TERM>
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<REPLACEABLE CLASS="PARAMETER">select</REPLACEABLE>
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</TERM>
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||||
<LISTITEM>
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||||
<PARA>
|
||||
A select statement with all features except the ORDER BY clause.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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</VARIABLELIST>
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</PARA>
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</REFSECT2>
|
||||
|
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<REFSECT2 ID="R2-SQL-SELECT-2">
|
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<REFSECT2INFO>
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||||
<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Outputs
|
||||
</TITLE>
|
||||
<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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Rows
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||||
</TERM>
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<LISTITEM>
|
||||
<PARA>
|
||||
The complete set of rows resulting from the query specification.
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||||
</PARA>
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||||
</LISTITEM>
|
||||
</VARLISTENTRY>
|
||||
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
<ReturnValue>count</ReturnValue>
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||||
</TERM>
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||||
<LISTITEM>
|
||||
<PARA>
|
||||
The count of rows returned by the query.
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||||
</PARA>
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||||
</LISTITEM>
|
||||
</VARLISTENTRY>
|
||||
</VARIABLELIST>
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||||
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||||
</REFSECT2>
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||||
</REFSYNOPSISDIV>
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||||
|
||||
<REFSECT1 ID="R1-SQL-SELECT-1">
|
||||
<REFSECT1INFO>
|
||||
<DATE>1998-04-15</DATE>
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||||
</REFSECT1INFO>
|
||||
<TITLE>
|
||||
Description
|
||||
</TITLE>
|
||||
<PARA>
|
||||
SELECT will get all rows which satisfy the WHERE condition
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||||
or all rows of a table if WHERE is omitted.
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||||
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||||
<PARA>
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||||
The GROUP BY clause allows a user to divide a table
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||||
conceptually into groups. (See GROUP BY clause).
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||||
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||||
<PARA>
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||||
The HAVING clause specifies a grouped table derived by the
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||||
elimination of groups from the result of the previously
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||||
specified clause. (See HAVING clause).
|
||||
|
||||
<PARA>
|
||||
The ORDER BY clause allows a user to specify that he/she
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||||
wishes the rows sorted according to the ASCending or
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||||
DESCending mode operator. (See ORDER BY clause)
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||||
|
||||
<PARA>
|
||||
The UNION clause specifies a table derived from a Cartesian
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||||
product union join. (See UNION clause).
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||||
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||||
<PARA>
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||||
You must have SELECT privilege to a table to read its values
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||||
(See GRANT/REVOKE statements).
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||||
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||||
<REFSECT2 ID="R2-SQL-WHERE-2">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
WHERE clause
|
||||
</TITLE>
|
||||
<PARA>
|
||||
The optional WHERE condition has the general form:
|
||||
|
||||
<Synopsis>
|
||||
WHERE <REPLACEABLE CLASS="PARAMETER">expr</REPLACEABLE> <REPLACEABLE CLASS="PARAMETER">cond_op</REPLACEABLE> <REPLACEABLE CLASS="PARAMETER">expr</REPLACEABLE> [<REPLACEABLE CLASS="PARAMETER">log_op</REPLACEABLE> ...]
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||||
</Synopsis>
|
||||
|
||||
where <REPLACEABLE CLASS="PARAMETER">cond_op</REPLACEABLE> can be one of: =, <, <=, >, >=, <>
|
||||
or a conditional operator like ALL, ANY, IN, LIKE, et cetera
|
||||
and <REPLACEABLE CLASS="PARAMETER">log_op</REPLACEABLE> can be one of: AND, OR, NOT.
|
||||
The comparison returns either TRUE or FALSE and all
|
||||
instances will be discarded
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||||
if the expression evaluates to FALSE.
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||||
</PARA>
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||||
</REFSECT2>
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||||
|
||||
<REFSECT2 ID="R2-SQL-GROUPBY-2">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
GROUP BY clause
|
||||
</TITLE>
|
||||
<PARA>
|
||||
GROUP BY specifies a grouped table derived by the application
|
||||
of the this clause:
|
||||
<SYNOPSIS>
|
||||
GROUP BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [, ...]
|
||||
</SYNOPSIS>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-HAVING-2">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
HAVING clause
|
||||
</TITLE>
|
||||
<PARA>
|
||||
The optional HAVING condition has the general form:
|
||||
|
||||
<Synopsis>
|
||||
HAVING <REPLACEABLE CLASS="PARAMETER">cond_expr</REPLACEABLE>
|
||||
</Synopsis>
|
||||
|
||||
where <REPLACEABLE CLASS="PARAMETER">cond_expr</REPLACEABLE> is the same
|
||||
as specified for the WHERE clause.
|
||||
|
||||
<Para>
|
||||
HAVING specifies a grouped table derived by the elimination
|
||||
of groups from the result of the previously specified clause
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||||
that do not meet the <REPLACEABLE CLASS="PARAMETER">cond_expr</REPLACEABLE>.
|
||||
|
||||
<Para>
|
||||
Each column referenced in <REPLACEABLE CLASS="PARAMETER">cond_expr</REPLACEABLE> shall unambiguously
|
||||
reference a grouping column.
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||||
</PARA>
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-ORDERBYCLAUSE-2">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
ORDER BY clause
|
||||
</TITLE>
|
||||
<PARA>
|
||||
<Synopsis>
|
||||
ORDER BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [ASC | DESC] [, ...]
|
||||
</Synopsis>
|
||||
|
||||
<PARA>
|
||||
<REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> can be either a column
|
||||
name or an ordinal number.
|
||||
<PARA>
|
||||
The ordinal numbers refers to the ordinal (left-to-right) position
|
||||
of the column. This feature makes it possible to define an ordering
|
||||
on the basis of a column that does not have a proper name.
|
||||
This is never absolutely necessary because it is always possible assign a name
|
||||
to a calculated column using the AS clause, e.g.:
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||||
<ProgramListing>
|
||||
SELECT title, date_prod + 1 AS newlen FROM films ORDER BY newlen;
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||||
</ProgramListing>
|
||||
|
||||
<PARA>
|
||||
The columns in the ORDER BY must appear in the SELECT clause.
|
||||
Thus the following statement is illegal:
|
||||
<ProgramListing>
|
||||
SELECT name FROM distributors ORDER BY code;
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||||
</ProgramListing>
|
||||
|
||||
<PARA>
|
||||
Optionally one may add the keyword DESC (descending)
|
||||
or ASC (ascending) after each column name in the ORDER BY clause.
|
||||
If not specified, ASC is assumed by default.
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-UNION-2">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
UNION clause
|
||||
</TITLE>
|
||||
<PARA>
|
||||
<Synopsis>
|
||||
<REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE> UNION [ALL] <REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE>
|
||||
[ORDER BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [ASC | DESC] [, ...] ]
|
||||
</Synopsis>
|
||||
|
||||
where
|
||||
<REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE>
|
||||
specifies any select expression without an ORDER BY clause.
|
||||
|
||||
<PARA>
|
||||
The UNION operator specifies a table derived from a Cartesian product.
|
||||
The two tables that represent the direct operands of the UNION must
|
||||
have the same number of columns, and corresponding columns must be
|
||||
of compatible data types.
|
||||
|
||||
<PARA>
|
||||
By default, the result of UNION does not contain any duplicate rows
|
||||
unless the ALL clause is specified.
|
||||
|
||||
<Para>
|
||||
Multiple UNION operators in the same SELECT statement are evaluated left to right.
|
||||
Note that the ALL keyword is not global in nature, being applied only for the current pair of
|
||||
table results.
|
||||
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-SELECT-2">
|
||||
<TITLE>
|
||||
Usage
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<ProgramListing>
|
||||
--Join table films with their distributors:
|
||||
--
|
||||
SELECT f.title, f.did, d.name, f.date_prod, f.kind
|
||||
FROM distributors d, films f
|
||||
WHERE f.did = d.did;
|
||||
|
||||
title |did|name | date_prod|kind
|
||||
-------------------------+---+----------------+----------+----------
|
||||
The Third Man |101|British Lion |1949-12-23|Drama
|
||||
The African Queen |101|British Lion |1951-08-11|Romantic
|
||||
Une Femme est une Femme |102|Jean Luc Godard |1961-03-12|Romantic
|
||||
Vertigo |103|Paramount |1958-11-14|Action
|
||||
Becket |103|Paramount |1964-02-03|Drama
|
||||
48 Hrs |103|Paramount |1982-10-22|Action
|
||||
War and Peace |104|Mosfilm |1967-02-12|Drama
|
||||
West Side Story |105|United Artists |1961-01-03|Musical
|
||||
Bananas |105|United Artists |1971-07-13|Comedy
|
||||
Yojimbo |106|Toho |1961-06-16|Drama
|
||||
There's a Girl in my Soup|107|Columbia |1970-06-11|Comedy
|
||||
Taxi Driver |107|Columbia |1975-05-15|Action
|
||||
Absence of Malice |107|Columbia |1981-11-15|Action
|
||||
Storia di una donna |108|Westward |1970-08-15|Romantic
|
||||
The King and I |109|20th Century Fox|1956-08-11|Musical
|
||||
Das Boot |110|Bavaria Atelier |1981-11-11|Drama
|
||||
Bed Knobs and Broomsticks|111|Walt Disney | |Musical
|
||||
</ProgramListing>
|
||||
|
||||
<ProgramListing>
|
||||
--sum column "len" of all films group by "kind":
|
||||
--
|
||||
SELECT kind, SUM(len) AS total FROM films GROUP BY kind;
|
||||
|
||||
kind |total
|
||||
----------+------
|
||||
Action | 07:34
|
||||
Comedy | 02:58
|
||||
Drama | 14:28
|
||||
Musical | 06:42
|
||||
Romantic | 04:38
|
||||
</ProgramListing>
|
||||
|
||||
<ProgramListing>
|
||||
--sum column length of all films group by "kind"
|
||||
--having total duration < 5 hours:
|
||||
--
|
||||
SELECT kind, SUM(len) AS total
|
||||
FROM films
|
||||
GROUP BY kind
|
||||
HAVING SUM(len) < INTERVAL '5 hour';
|
||||
|
||||
kind |total
|
||||
----------+------
|
||||
Comedy | 02:58
|
||||
Romantic | 04:38
|
||||
</ProgramListing>
|
||||
|
||||
<ProgramListing>
|
||||
--The following two examples are identicals:
|
||||
--
|
||||
SELECT * FROM distributors ORDER BY name;
|
||||
SELECT * FROM distributors ORDER BY 2;
|
||||
|
||||
did|name
|
||||
---+----------------
|
||||
109|20th Century Fox
|
||||
110|Bavaria Atelier
|
||||
101|British Lion
|
||||
107|Columbia
|
||||
102|Jean Luc Godard
|
||||
113|Luso films
|
||||
104|Mosfilm
|
||||
103|Paramount
|
||||
106|Toho
|
||||
105|United Artists
|
||||
111|Walt Disney
|
||||
112|Warner Bros.
|
||||
108|Westward
|
||||
</ProgramListing>
|
||||
|
||||
<ProgramListing>
|
||||
--union of table distributors and table actors:
|
||||
-- (only those that begin with letter W):
|
||||
--
|
||||
-- distributors: actors:
|
||||
-- did|name id|name
|
||||
-- ---+------------ --+--------------
|
||||
-- 108|Westward 1|Woody Allen
|
||||
-- 111|Walt Disney 2|Warren Beatty
|
||||
-- 112|Warner Bros. 3|Walter Matthau
|
||||
-- ... ...
|
||||
--
|
||||
--select only distinct rows (without ALL):
|
||||
--
|
||||
SELECT distributors.name
|
||||
FROM distributors
|
||||
WHERE distributors.name LIKE 'W%'
|
||||
UNION
|
||||
SELECT actors.name
|
||||
FROM actors
|
||||
WHERE actors.name LIKE 'W%';
|
||||
|
||||
name
|
||||
--------------
|
||||
Walt Disney
|
||||
Walter Matthau
|
||||
Warner Bros.
|
||||
Warren Beatty
|
||||
Westward
|
||||
Woody Allen
|
||||
</ProgramListing>
|
||||
|
||||
</REFSECT1>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-SELECT-3">
|
||||
<TITLE>
|
||||
Compatibility
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-SELECT-4">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
<Acronym>SQL92</Acronym>
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
|
||||
<REFSECT3 ID="R3-SQL-SELECT-1">
|
||||
<REFSECT3INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT3INFO>
|
||||
<TITLE>
|
||||
SELECT clause
|
||||
</TITLE>
|
||||
<PARA>
|
||||
In the <Acronym>SQL92</Acronym> standard, the optional keyword "AS" is just noise and can be
|
||||
omitted without affecting the meaning.
|
||||
The <ProductName>Postgres</ProductName> parser requires this keyword when
|
||||
renaming columns because the type extensibility features lead to parsing ambiguities
|
||||
in this context.
|
||||
|
||||
<PARA>
|
||||
In the <Acronym>SQL92</Acronym> standard, the new column name specified in an
|
||||
"AS" clause may be referenced in GROUP BY and HAVING clauses. This is not currently
|
||||
allowed in <ProductName>Postgres</ProductName>.
|
||||
</PARA>
|
||||
</REFSECT3>
|
||||
|
||||
<REFSECT3 ID="R3-SQL-UNION-1">
|
||||
<REFSECT3INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT3INFO>
|
||||
<TITLE>
|
||||
UNION clause
|
||||
</TITLE>
|
||||
<PARA>
|
||||
The <Acronym>SQL92</Acronym> syntax for UNION allows an additional CORRESPONDING BY clause:
|
||||
<Synopsis>
|
||||
<REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE> UNION [ALL]
|
||||
[CORRESPONDING [BY (<REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [,...])]]
|
||||
<REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE>
|
||||
</Synopsis>
|
||||
|
||||
<Para>
|
||||
The CORRESPONDING BY clause is not supported by <ProductName>Postgres</ProductName>.
|
||||
</PARA>
|
||||
</REFSECT3>
|
||||
|
||||
</REFSECT2>
|
||||
</REFSECT1>
|
||||
</REFENTRY>
|
||||
|
||||
<!--
|
||||
<REPLACEABLE CLASS="PARAMETER">
|
||||
</REPLACEABLE>
|
||||
<ReturnValue></ReturnValue>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>•
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
</PARA>
|
||||
</LISTITEM>
|
||||
</VARLISTENTRY>
|
||||
</VARIABLELIST>
|
||||
<PARA>
|
||||
</PARA>
|
||||
-->
|
||||
Reference in New Issue
Block a user