148 lines
4.9 KiB
Plaintext
148 lines
4.9 KiB
Plaintext
.\" This is -*-nroff-*-
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.\" XXX standard disclaimer belongs here....
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.\" $Header: /cvsroot/pgsql/src/man/Attic/create_table.l,v 1.23 1999/02/02 03:45:32 momjian Exp $
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.TH "CREATE TABLE" SQL 09/25/97 PostgreSQL
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.SH NAME
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create table - create a new class
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.SH SYNOPSIS
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.nf
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\fBcreate\fR [\fBtemp\fR] \fBtable\fR classname
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\fB(\fP
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attname type
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[\fBdefault\fP value]
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[[\fBnot null\fP] [\fBunique\fP] | [\fBprimary key\fP]]
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[\fBreferences\fP classname \fB(\fP attname \fB)\fP]
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[\fBcheck (\fP condition\fB )\fP]
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[\fB,\fP attname type [constraint] [\fB,\fP ...] ]
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[\fB, primary key ( \fPattname, attname[,...] \fB)\fP]
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[\fB, unique ( \fPattname, attname[,...] \fB)\fP]
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[\fB, foreign key ( \fPattname, attname[,...] \fB) references\fP classname]
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[\fB,\fP [\fBconstraint\fR cname] \fBcheck\fR \fB(\fR test \fB)\fR [, \fBcheck\fR \fB(\fR test \fB)\fR ] ]
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\fB)\fP
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[\fBinherits\fR \fB(\fR classname [\fB,\fR classname] \fB)\fR]
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.fi
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.SH DESCRIPTION
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.BR "Create Table"
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will enter a new class into the current data base. The class will be
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\*(lqowned\*(rq by the user issuing the command. The name of the
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class is
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.IR classname
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and the attributes are as specified in the list of
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.IR attname s.
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Each attribute is created with the type specified by
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.IR type "."
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Each type may be a simple type, a complex type (set) or an array type.
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Each attribute may be specified to be non-null and
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each may have a default value, specified by the
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.IR default
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clause which is the keyword "default" followed by a constant or expression.
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.PP
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Each array attribute stores arrays that must have the same number of
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dimensions but may have different sizes and array index bounds. An
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array of dimension
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.IR n
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is specified by appending
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.IR n
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pairs of square brackets:
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.nf
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att_name type[][]..[]
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.fi
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N.B. As of Postgres version 6.0, consistant array dimensions within an
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attribute are not enforced. This will likely change in a future release.
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.PP
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The optional
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.BR inherits
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clause specifies a collection of class names from which this class
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automatically inherits all fields. If any inherited field name
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appears more than once, Postgres reports an error. Postgres automatically
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allows the created class to inherit functions on classes above it in
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the inheritance hierarchy. Inheritance of functions is done according
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to the conventions of the Common Lisp Object System (CLOS).
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.PP
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Each new class
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.IR classname
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is automatically created as a type. Therefore, one or more instances
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from the class are automatically a type and can be used in
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.IR alter_table(l)
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or other
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.BR create_table(l)
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statements.
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.PP
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The optional
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.BR constraint
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clauses specify constraints or tests which new or updated entries
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must satisfy for an insert or update operation to succeed. Each constraint
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must evaluate to a boolean expression. Multiple attributes may be referenced within
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a single constraint. The use of \fBprimary key (\fPattname[\fB,\fP...]\fB)\fP
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as a table constraint
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is mutually incompatible with \fBprimary key\fP used as a column constraint.
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.PP
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The new class is created as a heap with no initial data. A class can
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have no more than 1600 attributes (realistically, this is limited by the
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fact that tuple sizes must be less than 8192 bytes), but this limit
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may be configured lower at some sites. A class cannot have the same
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name as a system catalog class.
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.PP
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.SH EXAMPLES
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.nf
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--
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-- Create class emp with attributes name, sal and bdate
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--
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create table emp (name name, salary float4, bdate abstime)
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.fi
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.nf
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--
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--Create class permemp with pension information that
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--inherits all fields of emp
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--
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create table permemp (plan name) inherits (emp)
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.fi
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.nf
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--
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--Create class emppay with attributes name and wage with
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--a default salary and constraints on wage range
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--
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create table emppay (name text not null, wage float4 default 10.00
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constraint empcon check (wage > 5.30 and wage <= 30.00), check (name <> ''))
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.fi
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.nf
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--
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--Create class tictactoe to store noughts-and-crosses
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--boards as a 2-dimensional array
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--
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create table tictactoe (game int4, board char[][])
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.fi
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.nf
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--
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--Create a class newemp with a set attribute "manager". A
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--set (complex) attribute may be of the same type as the
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--relation being defined (as here) or of a different complex
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--type. The type must exist in the "pg_type" catalog or be
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--the one currently being defined.
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--
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create table newemp (name text, manager newemp)
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.fi
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.nf
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--
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--Create a table using SQL92 syntax
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create table component
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(
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assembly char(8) not null
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references job (id),
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product char(8) not null
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references product (id),
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sorting int,
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qty int check (qty >= 0),
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primary key (assembly, product),
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unique (assembly, product, sorting),
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constraint not_same check (assembly != product)
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)
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.fi
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.PP
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.SH BUGS
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The \fBforeign key\fP and \fBreferences\fP keywords are parsed but not yet
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implemented in PostgreSQL 6.3.1.
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.SH "SEE ALSO"
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drop_table(l).
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