# Manpages - DBI_SQL_Nano.3pm




## NAME

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

## SYNOPSIS

### Supported SQL syntax

Heres 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 doesnt 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.