oracular (3) DBI::SQL::Nano.3pm.gz

NAME

       DBI::SQL::Nano - a very tiny SQL engine

SYNOPSIS

        BEGIN { $ENV{DBI_SQL_NANO}=1 } # forces use of Nano rather than SQL::Statement
        use DBI::SQL::Nano;
        use Data::Dumper;
        my $stmt = DBI::SQL::Nano::Statement->new(
            "SELECT bar,baz FROM foo WHERE qux = 1"
        ) or die "Couldn't parse";
        print Dumper $stmt;

DESCRIPTION

       "DBI::SQL::Nano" is meant as a very minimal SQL engine for use in situations where SQL::Statement is not
       available. In most situations you are better off installing SQL::Statement although DBI::SQL::Nano may be
       faster for some very simple tasks.

       DBI::SQL::Nano, like SQL::Statement is primarily intended to provide a SQL engine for use with some pure
       perl DBDs including DBD::DBM, DBD::CSV, DBD::AnyData, and DBD::Excel. It is not of much use in and of
       itself.  You can dump out the structure of a parsed SQL statement, but that is about it.

USAGE

   Setting the DBI_SQL_NANO flag
       By default, when a "DBD" uses "DBI::SQL::Nano", the module will look to see if "SQL::Statement" is
       installed. If it is, SQL::Statement objects are used.  If SQL::Statement is not available, DBI::SQL::Nano
       objects are used.

       In some cases, you may wish to use DBI::SQL::Nano objects even if SQL::Statement is available.  To force
       usage of DBI::SQL::Nano objects regardless of the availability of SQL::Statement, set the environment
       variable DBI_SQL_NANO to 1.

       You can set the environment variable in your shell prior to running your script (with SET or EXPORT or
       whatever), or else you can set it in your script by putting this at the top of the script:

        BEGIN { $ENV{DBI_SQL_NANO} = 1 }

   Supported SQL syntax
        Here's a pseudo-BNF.  Square brackets [] indicate optional items;
        Angle brackets <> indicate items defined elsewhere in the BNF.

         statement ::=
             DROP TABLE [IF EXISTS] <table_name>
           | CREATE TABLE <table_name> <col_def_list>
           | INSERT INTO <table_name> [<insert_col_list>] VALUES <val_list>
           | DELETE FROM <table_name> [<where_clause>]
           | UPDATE <table_name> SET <set_clause> <where_clause>
           | SELECT <select_col_list> FROM <table_name> [<where_clause>]
                                                        [<order_clause>]

         the optional IF EXISTS clause ::=
           * similar to MySQL - prevents errors when trying to drop
             a table that doesn't exist

         identifiers ::=
           * table and column names should be valid SQL identifiers
           * especially avoid using spaces and commas in identifiers
           * note: there is no error checking for invalid names, some
             will be accepted, others will cause parse failures

         table_name ::=
           * only one table (no multiple table operations)
           * see identifier for valid table names

         col_def_list ::=
           * a parens delimited, comma-separated list of column names
           * see identifier for valid column names
           * column types and column constraints may be included but are ignored
             e.g. these are all the same:
               (id,phrase)
               (id INT, phrase VARCHAR(40))
               (id INT PRIMARY KEY, phrase VARCHAR(40) NOT NULL)
           * you are *strongly* advised to put in column types even though
             they are ignored ... it increases portability

         insert_col_list ::=
           * a parens delimited, comma-separated list of column names
           * as in standard SQL, this is optional

         select_col_list ::=
           * a comma-separated list of column names
           * or an asterisk denoting all columns

         val_list ::=
           * a parens delimited, comma-separated list of values which can be:
              * placeholders (an unquoted question mark)
              * numbers (unquoted numbers)
              * column names (unquoted strings)
              * nulls (unquoted word NULL)
              * strings (delimited with single quote marks);
              * note: leading and trailing percent mark (%) and underscore (_)
                can be used as wildcards in quoted strings for use with
                the LIKE and CLIKE operators
              * note: escaped single quotation marks within strings are not
                supported, neither are embedded commas, use placeholders instead

         set_clause ::=
           * a comma-separated list of column = value pairs
           * see val_list for acceptable value formats

         where_clause ::=
           * a single "column/value <op> column/value" predicate, optionally
             preceded by "NOT"
           * note: multiple predicates combined with ORs or ANDs are not supported
           * see val_list for acceptable value formats
           * op may be one of:
                < > >= <= = <> LIKE CLIKE IS
           * CLIKE is a case insensitive LIKE

         order_clause ::= column_name [ASC|DESC]
           * a single column optional ORDER BY clause is supported
           * as in standard SQL, if neither ASC (ascending) nor
             DESC (descending) is specified, ASC becomes the default

TABLES

       DBI::SQL::Nano::Statement operates on exactly one table. This table will be opened by inherit from
       DBI::SQL::Nano::Statement and implements the "open_table" method.

         sub open_table ($$$$$)
         {
             ...
             return Your::Table->new( \%attributes );
         }

       DBI::SQL::Nano::Statement_ expects a rudimentary interface is implemented by the table object, as well as
       SQL::Statement expects.

         package Your::Table;

         use vars qw(@ISA);
         @ISA = qw(DBI::SQL::Nano::Table);

         sub drop ($$)        { ... }
         sub fetch_row ($$$)  { ... }
         sub push_row ($$$)   { ... }
         sub push_names ($$$) { ... }
         sub truncate ($$)    { ... }
         sub seek ($$$$)      { ... }

       The base class interfaces are provided by DBI::SQL::Nano::Table_ in case of relying on DBI::SQL::Nano or
       SQL::Eval::Table (see SQL::Eval for details) otherwise.

BUGS AND LIMITATIONS

       There are no known bugs in DBI::SQL::Nano::Statement. If you find a one and want to report, please see
       DBI for how to report bugs.

       DBI::SQL::Nano::Statement is designed to provide a minimal subset for executing SQL statements.

       The most important limitation might be the restriction on one table per statement. This implies, that no
       JOINs are supported and there cannot be any foreign key relation between tables.

       The where clause evaluation of DBI::SQL::Nano::Statement is very slow (SQL::Statement uses a precompiled
       evaluation).

       INSERT can handle only one row per statement. To insert multiple rows, use placeholders as explained in
       DBI.

       The DBI::SQL::Nano parser is very limited and does not support any additional syntax such as brackets,
       comments, functions, aggregations etc.

       In contrast to SQL::Statement, temporary tables are not supported.

ACKNOWLEDGEMENTS

       Tim Bunce provided the original idea for this module, helped me out of the tangled trap of namespaces,
       and provided help and advice all along the way.  Although I wrote it from the ground up, it is based on
       Jochen Wiedmann's original design of SQL::Statement, so much of the credit for the API goes to him.

AUTHOR AND COPYRIGHT

       This module is originally written by Jeff Zucker < jzucker AT cpan.org >

       This module is currently maintained by Jens Rehsack < jrehsack AT cpan.org >

       Copyright (C) 2010 by Jens Rehsack, all rights reserved.  Copyright (C) 2004 by Jeff Zucker, all rights
       reserved.

       You may freely distribute and/or modify this module under the terms of either the GNU General Public
       License (GPL) or the Artistic License, as specified in the Perl README file.