1DBI::SQL::Nano(3) User Contributed Perl Documentation DBI::SQL::Nano(3)
2
6 DBI::SQL::Nano - a very tiny SQL engine
7
9 BEGIN { $ENV{DBI_SQL_NANO}=1 } # forces use of Nano rather than SQL::Statement
10 use DBI::SQL::Nano;
11 use Data::Dumper;
12 my $stmt = DBI::SQL::Nano::Statement->new(
13 "SELECT bar,baz FROM foo WHERE qux = 1"
14 ) or die "Couldn't parse";
15 print Dumper $stmt;
16
18 "DBI::SQL::Nano" is meant as a very minimal SQL engine for use in
19 situations where SQL::Statement is not available. In most situations
20 you are better off installing SQL::Statement although DBI::SQL::Nano
21 may be faster for some very simple tasks.
22 DBI::SQL::Nano, like SQL::Statement is primarily intended to provide a
24 SQL engine for use with some pure perl DBDs including DBD::DBM,
25 DBD::CSV, DBD::AnyData, and DBD::Excel. It is not of much use in and of
26 itself. You can dump out the structure of a parsed SQL statement, but
27 that is about it.
28
30 Setting the DBI_SQL_NANO flag
31 By default, when a "DBD" uses "DBI::SQL::Nano", the module will look to
32 see if "SQL::Statement" is installed. If it is, SQL::Statement objects
33 are used. If SQL::Statement is not available, DBI::SQL::Nano objects
34 are used.
35 In some cases, you may wish to use DBI::SQL::Nano objects even if
37 SQL::Statement is available. To force usage of DBI::SQL::Nano objects
38 regardless of the availability of SQL::Statement, set the environment
39 variable DBI_SQL_NANO to 1.
40 You can set the environment variable in your shell prior to running
42 your script (with SET or EXPORT or whatever), or else you can set it in
43 your script by putting this at the top of the script:
44 BEGIN { $ENV{DBI_SQL_NANO} = 1 }
46 Supported SQL syntax
48 Here's a pseudo-BNF. Square brackets [] indicate optional items;
49 Angle brackets <> indicate items defined elsewhere in the BNF.
50 statement ::=
52 DROP TABLE [IF EXISTS] <table_name>
53 | CREATE TABLE <table_name> <col_def_list>
54 | INSERT INTO <table_name> [<insert_col_list>] VALUES <val_list>
55 | DELETE FROM <table_name> [<where_clause>]
56 | UPDATE <table_name> SET <set_clause> <where_clause>
57 | SELECT <select_col_list> FROM <table_name> [<where_clause>]
58 [<order_clause>]
59 the optional IF EXISTS clause ::=
61 * similar to MySQL - prevents errors when trying to drop
62 a table that doesn't exist
63 identifiers ::=
65 * table and column names should be valid SQL identifiers
66 * especially avoid using spaces and commas in identifiers
67 * note: there is no error checking for invalid names, some
68 will be accepted, others will cause parse failures
69 table_name ::=
71 * only one table (no multiple table operations)
72 * see identifier for valid table names
73 col_def_list ::=
75 * a parens delimited, comma-separated list of column names
76 * see identifier for valid column names
77 * column types and column constraints may be included but are ignored
78 e.g. these are all the same:
79 (id,phrase)
80 (id INT, phrase VARCHAR(40))
81 (id INT PRIMARY KEY, phrase VARCHAR(40) NOT NULL)
82 * you are *strongly* advised to put in column types even though
83 they are ignored ... it increases portability
84 insert_col_list ::=
86 * a parens delimited, comma-separated list of column names
87 * as in standard SQL, this is optional
88 select_col_list ::=
90 * a comma-separated list of column names
91 * or an asterisk denoting all columns
92 val_list ::=
94 * a parens delimited, comma-separated list of values which can be:
95 * placeholders (an unquoted question mark)
96 * numbers (unquoted numbers)
97 * column names (unquoted strings)
98 * nulls (unquoted word NULL)
99 * strings (delimited with single quote marks);
100 * note: leading and trailing percent mark (%) and underscore (_)
101 can be used as wildcards in quoted strings for use with
102 the LIKE and CLIKE operators
103 * note: escaped single quotation marks within strings are not
104 supported, neither are embedded commas, use placeholders instead
105 set_clause ::=
107 * a comma-separated list of column = value pairs
108 * see val_list for acceptable value formats
109 where_clause ::=
111 * a single "column/value <op> column/value" predicate, optionally
112 preceded by "NOT"
113 * note: multiple predicates combined with ORs or ANDs are not supported
114 * see val_list for acceptable value formats
115 * op may be one of:
116 < > >= <= = <> LIKE CLIKE IS
117 * CLIKE is a case insensitive LIKE
118 order_clause ::= column_name [ASC|DESC]
120 * a single column optional ORDER BY clause is supported
121 * as in standard SQL, if neither ASC (ascending) nor
122 DESC (descending) is specified, ASC becomes the default
123
125 DBI::SQL::Nano::Statement operates on exactly one table. This table
126 will be opened by inherit from DBI::SQL::Nano::Statement and implements
127 the "open_table" method.
128 sub open_table ($$$$$)
130 {
131 ...
132 return Your::Table->new( \%attributes );
133 }
134 DBI::SQL::Nano::Statement_ expects a rudimentary interface is
136 implemented by the table object, as well as SQL::Statement expects.
137 package Your::Table;
139 use vars qw(@ISA);
141 @ISA = qw(DBI::SQL::Nano::Table);
142 sub drop ($$) { ... }
144 sub fetch_row ($$$) { ... }
145 sub push_row ($$$) { ... }
146 sub push_names ($$$) { ... }
147 sub truncate ($$) { ... }
148 sub seek ($$$$) { ... }
149 The base class interfaces are provided by DBI::SQL::Nano::Table_ in
151 case of relying on DBI::SQL::Nano or SQL::Eval::Table (see SQL::Eval
152 for details) otherwise.
153
155 There are no known bugs in DBI::SQL::Nano::Statement. If you find a one
156 and want to report, please see DBI for how to report bugs.
157 DBI::SQL::Nano::Statement is designed to provide a minimal subset for
159 executing SQL statements.
160 The most important limitation might be the restriction on one table per
162 statement. This implies, that no JOINs are supported and there cannot
163 be any foreign key relation between tables.
164 The where clause evaluation of DBI::SQL::Nano::Statement is very slow
166 (SQL::Statement uses a precompiled evaluation).
167 INSERT can handle only one row per statement. To insert multiple rows,
169 use placeholders as explained in DBI.
170 The DBI::SQL::Nano parser is very limited and does not support any
172 additional syntax such as brackets, comments, functions, aggregations
173 etc.
174 In contrast to SQL::Statement, temporary tables are not supported.
176
178 Tim Bunce provided the original idea for this module, helped me out of
179 the tangled trap of namespaces, and provided help and advice all along
180 the way. Although I wrote it from the ground up, it is based on Jochen
181 Wiedmann's original design of SQL::Statement, so much of the credit for
182 the API goes to him.
183
185 This module is originally written by Jeff Zucker < jzucker AT cpan.org
186 >
187 This module is currently maintained by Jens Rehsack < jrehsack AT
189 cpan.org >
190 Copyright (C) 2010 by Jens Rehsack, all rights reserved. Copyright (C)
192 2004 by Jeff Zucker, all rights reserved.
193 You may freely distribute and/or modify this module under the terms of
195 either the GNU General Public License (GPL) or the Artistic License, as
196 specified in the Perl README file.
197perl v5.32.1 2021-01-27 DBI::SQL::Nano(3)