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doc/man/select.l

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+.\" This is -*-nroff-*-
+.\" XXX standard disclaimer belongs here....
+.\" $Header: /cvsroot/pgsql/doc/man/Attic/select.l,v 1.1.1.1 1996/08/18 22:14:27 scrappy Exp $
+.TH SELECT SQL 11/05/95 Postgres95 Postgres95
+.SH NAME
+select \(em retrieve instances from a class
+.SH SYNOPSIS
+.nf
+\fBselect\fR [distinct]
+    expression1 [\fBas\fR attr_name-1]
+    {, expression-1 [\fBas\fR attr_name-i]}
+    [\fBinto\fR \fBtable\fR classname]
+    [\fBfrom\fR from-last]
+    [\fBwhere\fR where-clause]    
+    [\fBgroup by\fR attr_name1 {, attr_name-i....}
+    [\fBorder by\fR attr_name1
+	[\fBusing op1\fR] {, attr_namei [\fBusing opi\fR] }
+.fi
+.SH DESCRIPTION
+.BR Select
+will get all instances which satisfy the qualification,
+.IR qual ,
+compute the value of each element in the target list, and either (1)
+return them to an application program through one of two different
+kinds of portals or (2) store them in a new class.
+.PP
+If
+into table class name
+is specified, the result of the query will be stored in a new class
+with the indicated name.
+.PP
+The
+.BR "order by"
+clause allows a user to specify that he wishes the instances sorted
+according to the corresponding operator.  This operator must be a
+binary one returning a boolean.  Multiple sort fields are allowed and
+are applied from left to right.
+.PP
+The target list specifies the fields to be retrieved.  Each 
+.IR attr_name
+specifies the desired attribute or portion of an array attribute.
+Thus, each 
+.IR attr_name
+takes the form
+.nf
+class_name.att_name
+.fi
+or, if the user only desires part of an array,
+.nf
+--
+--Specify a lower and upper index for each dimension
+--(i.e., clip a range of array elements)
+--
+class_name.att_name[lIndex-1:uIndex-1]..[lIndex-i:uIndex-i]
+
+--
+--Specify an exact array element
+--
+class_name.att_name[uIndex-1]..[uIndex-i]
+.fi
+where each 
+.IR lIndex
+or
+.IR uIndex
+is an integer constant.
+.PP
+When you retrieve an attribute which is of a complex type, the behavior
+of the system depends on whether you used "nested dots" to project
+out attributes of the complex type or not.  See the examples below.
+.PP
+You must have read access to a class to read its values (see
+.IR "grant/revoke" (l).
+.SH EXAMPLES
+.nf
+--
+--Find all employees who make more than their manager
+--
+select e.name
+   from emp e, emp m
+   where e.mgr = m.name
+   and e.sal >  m.sal
+.fi
+.nf
+--
+--Retrieve all fields for those employees who make
+--more than the average salary
+--
+select avg(sal) as ave 
+   into table avgsal from emp;
+.fi
+.nf
+--
+--Retrieve all employee names in sorted order
+--
+select distinct name
+   from emp
+   order by name using <
+.fi
+.nf
+--
+--Retrieve all employee names that were valid on 1/7/85 
+--in sorted order
+--
+selec name
+   from emp['January 7 1985'] e
+   order by name using < 
+.fi
+.nf
+--
+--Construct a new class, raise, containing 1.1
+--times all employee's salaries
+--
+select 1.1 * emp.salary as salary
+    into tables raise
+    from emp
+.fi
+.SH "SEE ALSO"
+insert(l),
+close(l),
+create table(l),
+fetch(l),
+update(l).
+.SH BUGS
+.BR "Select into"
+does not delete duplicates.
+.PP
+If the backend crashes in the course of executing a 
+.BR "select into" ,
+the class file will remain on disk.  It can be safely removed by the
+database DBA, but a subsequent
+.BR "select into"
+to the same name will fail with a cryptic error message about
+\*(lqBlockExtend\*(rq.