- GENERATING SQL
- Entry Points
- select (Alzabo::Table and/or Alzabo::Column objects)
- update (Alzabo::Table)
- Other Methods
- from (Alzabo::Table object, ...)
- where <see below>
- and (same as where)
- or (same as where)
- order_by (Alzabo::Column objects)
- limit ($max, optional $offset)
- into (Alzabo::Table object, optional Alzabo::Column objects)
- values (Alzabo::Column object => $value, ...)
- set (Alzabo::Column object => $value, ...)
- RETRIEVING SQL FROM THE OBJECT
- SUBCLASSING Alzabo::SQLMaker
- VIRTUAL METHODS
Alzabo::SQLMaker - Alzabo base class for RDBMS drivers
use Alzabo::SQLMaker::MySQL; my $sql = Alzabo::SQLMaker::MySQL->new( driver => $driver_object ); # or better yet my $sql = $runtime_schema->sqlmaker;
This is the base class for all Alzabo::SQLMaker modules. To instantiate a driver call this class's
new method. See "SUBCLASSING Alzabo::SQLMaker" for information on how to make a driver for the RDBMS of your choice.
Returns A list of names representing the available
Alzabo::SQLMaker subclasses. Any one of these names would be appropriate as a parameter for the
Load the specified subclass.
This takes one parameter, the name of the RDBMS being used.
This takes two parameters:
The driver object being used by the schema.
A boolean value indicating whether or not identifiers should be quoted. This defaults to false.
This class can be used to generate SQL by calling methods that are the same as those used in SQL (
update(), etc.) in sequence, with the appropriate parameters.
These methods are called as class methods and return a new object.
This begins a select. The columns to be selected are the column(s) passed in, and/or the columns of the table(s) passed in as arguments.
All of these methods return the object itself, making it possible to chain together method calls such as:
Alzabo::SQLMaker->select($column)->from($table)->where($other_column, '>', 2);
The table(s) from which we are selecting data.
The first parameter to where must be an
Alzabo::Column object or SQL function. The second is a comparison operator of some sort, given as a string. The third argument can be an
Alzabo::Column object, a value (a number or string), or an
Alzabo::SQLMaker object. The latter is treated as a subselect.
Values given as parameters will be properly quoted and escaped.
Some comparison operators allow additional parameters.
BETWEEN comparison operator requires a fourth argument. This must be either an
Alzabo::Column object or a value.
IN and <NOT IN> operators allow any number of additional parameters, which may be
Alzabo::Column objects, values, or
These methods take the same parameters as the
ORDER BY clause to your SQL.
Specifies a limit on the number of rows to be returned. The offset parameter is optional.
Used to specify what table an insert is into. If column objects are given then it is expected that values will only be given for that object. Otherwise, it assumed that all columns will be specified in the
This method expects to recive an structured like a hash where the keys are
Alzabo::Column objects and the values are the value to be inserted into that column.
This method'a parameter are exactly like those given to the
This method can be called at any time, though obviously it will not return valid SQL unless called at a natural end point. In the future, an exception may be thrown if called when the SQL is not in a valid state.
Returns the SQL generated so far as a string.
Returns an array reference containing the parameters to be bound to the SQL statement.
To create a subclass of
Alzabo::SQLMaker for your particular RDBMS requires only that the virtual methods listed below be implemented.
In addition, you may choose to override any of the other methods described in this documentation. For example, the MySQL subclass override the
_subselect() method because MySQL cannot support sub-selects.
Subclasses are also expected to offer for export various sets of functions matching SQL functions. See the
Alzabo::SQLMaker::MySQL subclass implementation for details.
The following methods must be implemented by the subclass:
See above for the definition of this method.
This method may return
undef even if the
limit() method was called. Some RDBMS's have special SQL syntax for
LIMIT clauses. For those that don't support this, the
Alzabo::Driver module takes a "limit" parameter.
The return value of this method can be passed in as that parameter.
If the RDBMS does not support
LIMIT clauses, the return value is an array reference containing two values, the maximum number of rows allowed and the row offset (the first row that should be used).
If the RDBMS does support
LIMIT clauses, then the return value is
Returns the subclass's name. This should be something that can be passed to
Alzabo::SQLMaker->load() as a parameter.
Dave Rolsky, <email@example.com>