--- /dev/null
+=head1 NAME
+
+SQL::Abstract::Manual::Specification
+
+=head1 DESCRIPTION
+
+These are the examples for the AST
+
+=head1 EXAMPLES
+
+The following are example SQL statements and the AST that would represent each
+one. The SQL used is from the MySQL dialect.
+
+=over 4
+
+=item * SELECT 1
+
+ {
+ type => 'select',
+ ast_version => 0.0001,
+ select => [
+ {
+ type => 'SelectComponent',
+ value => {
+ type => 'Value',
+ subtype => 'number',
+ value => 1,
+ },
+ },
+ ],
+ }
+
+=item * SELECT NOW() AS time FROM dual AS duality
+
+ {
+ type => 'select',
+ ast_version => 0.0001,
+ select => [
+ {
+ type => 'SelectComponent',
+ value => {
+ type => 'Function',
+ function => 'NOW',
+ },
+ as => {
+ type => 'Identifier',
+ element1 => 'time',
+ },
+ },
+ ],
+ tables => {
+ type => 'TableIdentifier',
+ value => {
+ type => 'Identifier',
+ element1 => 'dual',
+ },
+ as => 'duality',
+ },
+ }
+
+=item * SELECT 1 FROM foo LEFT OUTER JOIN bar ON ( foo.col1 = bar.col2 )
+
+ {
+ type => 'select',
+ ast_version => 0.0001,
+ select => [
+ {
+ type => 'SelectComponent',
+ value => {
+ type => 'Value',
+ subtype => 'number',
+ value => 1,
+ },
+ },
+ ],
+ tables => {
+ type => 'Operator',
+ op => 'LEFT OUTER',
+ args => [
+ {
+ type => 'TableIdentifier',
+ value => {
+ type => 'Identifier',
+ element1 => 'foo',
+ },
+ },
+ {
+ type => 'TableIdentifier',
+ value => {
+ type => 'Identifier',
+ element1 => 'bar',
+ },
+ },
+ ],
+ on => {
+ type => 'Operator',
+ op => '=',
+ args => [
+ {
+ type => 'Identifier',
+ element1 => 'foo',
+ element2 => 'col1',
+ },
+ {
+ type => 'Identifier',
+ element1 => 'bar',
+ element2 => 'col2',
+ },
+ ],
+ },
+ },
+ }
+
+=back
+
+=head1 AUTHORS
+
+robkinyon: Rob Kinyon C<< <rkinyon@cpan.org> >>
+
+=head1 LICENSE
+
+You may distribute this code under the same terms as Perl itself.
+
+=cut
The AST will be a HoHo..oH (hash of hash of ... of hashes). The keys to the
outermost hash will be the various clauses of a SQL statement, plus some
-metadata keys. All metadata keys will be identifiable as such by being prefixed
-with an underscore. All keys will be in lowercase.
+metadata keys.
=head2 Metadata keys
These are the additional metadata keys that the AST provides for.
-=head3 _query
+=head3 type
This denotes what kind of query this AST should be interpreted as. Different
-Visitors may accept additional values for _query. For example, a MySQL Visitor
-may choose to accept 'replace' for REPLACE INTO. If a _query value is
+Visitors may accept additional values for type. For example, a MySQL Visitor
+may choose to accept 'replace' for REPLACE INTO. If a type value is
unrecognized by the Visitor, the Visitor is expected to throw an error.
-All Visitors are expected to handle the following values for _query:
+All Visitors are expected to handle the following values for type:
=over 4
=back
-=head3 _version
+=head3 ast_version
This denotes the version of the AST. Different versions will indicate different
-capabilities provided. Visitors will choose to respect the _version as needed
+capabilities provided. Visitors will choose to respect the ast_version as needed
and desired.
=head2 Structural units
=head3 Subquery
-A Subquery is another AST whose _query metadata parameter is set to "SELECT".
+A Subquery is another AST whose type metadata parameter is set to "SELECT".
Most places that a Subquery can be used would require a single value to be
returned (single column, single row), but that is not something that the AST can
This is a list of tables that this clause is affecting. It corresponds to the
FROM clause in a SELECT statement and the INSERT INTO/UPDATE/DELETE clauses in
-those respective statements. Depending on the _query metadata entry, the
+those respective statements. Depending on the type metadata entry, the
appropriate clause name will be used.
The tables clause has several RDBMS-specific variations. The AST will support
This corresponds to the WHERE clause in a SELECT, UPDATE, or DELETE statement.
-A where clause is composed as follows:
-
- WhereOperator := AND | OR
- WhereExpression := Expression | Expression WhereOperator Expression
-
- WhereExpression
+A where clause is composed of an Expression.
=head3 set
Identifier, WhereExpression
-=head1 EXAMPLES
-
-The following are example SQL statements and a possible AST for each one.
-
-=over 4
-
-=item * SELECT 1
-
- {
- _query => 'select',
- _ast_version => 0.0001,
- select => [
- {
- type => 'SelectComponent',
- value => {
- type => 'Value',
- subtype => 'number',
- value => 1,
- },
- },
- ],
- }
-
-=item * SELECT NOW() AS time FROM dual AS duality
-
- {
- _query => 'select',
- _ast_version => 0.0001,
- select => [
- {
- type => 'SelectComponent',
- value => {
- type => 'Function',
- function => 'NOW',
- },
- as => {
- type => 'Identifier',
- element1 => 'time',
- },
- },
- ],
- tables => {
- type => 'TableIdentifier',
- value => {
- type => 'Identifier',
- element1 => 'dual',
- },
- as => 'duality',
- },
- }
-
-=item * SELECT 1 FROM foo LEFT OUTER JOIN bar ON ( foo.col1 = bar.col2 )
-
- {
- _query => 'select',
- _ast_version => 0.0001,
- select => [
- {
- type => 'SelectComponent',
- value => {
- type => 'Value',
- subtype => 'number',
- value => 1,
- },
- },
- ],
- tables => {
- type => 'Operator',
- op => 'LEFT OUTER',
- args => [
- {
- type => 'TableIdentifier',
- value => {
- type => 'Identifier',
- element1 => 'foo',
- },
- },
- {
- type => 'TableIdentifier',
- value => {
- type => 'Identifier',
- element1 => 'bar',
- },
- },
- ],
- on => {
- type => 'Operator',
- op => '=',
- args => [
- {
- type => 'Identifier',
- element1 => 'foo',
- element2 => 'col1',
- },
- {
- type => 'Identifier',
- element1 => 'bar',
- element2 => 'col2',
- },
- ],
- },
- },
- }
-
-=back
-
=head1 TODO
=over 4
projects / dbsrgits/SQL-Abstract-2.0-ish.git / commitdiff