NAME

NAME
DB::Object - SQL API

SYNOPSIS
use DB::Object;

my $dbh = DB::Object->connect({
driver => 'Pg',
conf_file => 'db-settings.json',
database => 'webstore',
host => 'localhost',
login => 'store-admin',
schema => 'auth',
debug => 3,
}) || bailout( "Unable to connect to sql server on host localhost: ", DB::Object->error );

# Legacy regular query
my $sth = $dbh->prepare( "SELECT login,name FROM login WHERE login='jack'" ) ||
die( $dbh->errstr() );
$sth->execute() || die( $sth->errstr() );
my $ref = $sth->fetchrow_hashref();
$sth->finish();

# Get a list of databases;
my @databases = $dbh->databases;
# Doesn't exist? Create it:
my $dbh2 = $dbh->create_db( 'webstore' );
# Load some sql into it
my $rv = $dbh2->do( $sql ) || die( $dbh->error );

# Check a table exists
$dbh->table_exists( 'customers' ) || die( "Cannot find the customers table!\n" );

# Get list of tables, as array reference:
my $tables = $dbh->tables;

my $cust = $dbh->customers || die( "Cannot get customers object." );
$cust->where( email => '[email protected]' );
my $str = $cust->delete->as_string;
# Becomes: DELETE FROM customers WHERE email='john\@example.org'

# Do some insert with transaction
$dbh->begin_work;
# Making some other inserts and updates here...
my $cust_sth_ins = $cust->insert(
first_name => 'Paul',
last_name => 'Goldman',
email => '[email protected]',
active => 0,
) || do
{
# Rollback everything since the begin_work
$dbh->rollback;
die( "Error while create query to add data to table customers: " . $cust->error );
};
$result = $cust_sth_ins->as_string;
# INSERT INTO customers (first_name, last_name, email, active) VALUES('Paul', 'Goldman', 'paul\@example.org', '0')
$dbh->commit;
## Get the last used insert id
my $id = $dbh->last_insert_id();

$cust->where( email => '[email protected]' );
$cust->order( 'last_name' );
$cust->having( email => qr/\@example/ );
$cust->limit( 10 );
my $cust_sth_sel = $cust->select || die( "An error occurred while creating a query to select data frm table customers: " . $cust->error );
# Becomes:
# SELECT id, first_name, last_name, email, created, modified, active, created::ABSTIME::INTEGER AS created_unixtime, modified::ABSTIME::INTEGER AS modified_unixtime, CONCAT(first_name, ' ', last_name) AS name FROM customers WHERE email='john\@example.org' HAVING email ~ '\@example' ORDER BY last_name LIMIT 10

$cust->reset;
$cust->where( email => '[email protected]' );
my $cust_sth_upd = $cust->update( active => 0 )
# Would become:
# UPDATE ONLY customers SET active='0' WHERE email='john\@example.org'

## Lets' dump the result of our query
## First to STDERR
$login->where( "login='jack'" );
$login->select->dump();
## Now dump the result to a file
$login->select->dump( "my_file.txt" );

VERSION
v0.9.7

DESCRIPTION
DB::Object is a SQL API much alike "DBI". So why use a private module
instead of using that great "DBI" package?

At first, I started to inherit from "DBI" to conform to "perlmod" perl
manual page and to general perl coding guidlines. It became very quickly
a real hassle. Barely impossible to inherit, difficulty to handle error,
too much dependent from an API that change its behaviour with new
versions. In short, I wanted a better, more accurate control over the
SQL connection.

So, DB::Object acts as a convenient, modifiable wrapper that provide the
programmer with an intuitive, user-friendly and hassle free interface.

CONSTRUCTOR
new()
Create a new instance of DB::Object. Nothing much to say.

connect( [ DATABASE, LOGIN, PASSWORD, SERVER[:PORT], DRIVER, SCHEMA ] |
%PARAMETERS | \%PARAMETERS )
Create a new instance of DB::Object, but also attempts a conection
to SQL server.

It can take either an array of value in the order database name,
login, password, host, driver and optionally schema, or it can take
a has or hash reference. The hash or hash reference attributes are
as follow:

*database* or *DB_NAME*
The database name you wish to connect to

*login* or *DB_LOGIN*
The login used to access that database

*passwd* or *DB_PASSWD*
The password that goes along

*host* or *DB_HOST*
The server, that is hostname of the machine serving a SQL
server.

*port* or *DB_PORT*
The port to connect to

*driver* or *DB_DRIVER*
The driver you want to use. It needs to be of the same type
than the server you want to connect to. If you are
connecting to a MySQL server, you would use "mysql", if you
would connecto to an Oracle server, you would use "oracle".

You need to make sure that those driver are properly
installed in the system before attempting to connect.

To install the required driver, you could start with the
command line:

perl -MCPAN -e shell

which will provide you a special shell to install modules in
a convenient way.

*schema* or *DB_SCHEMA*
The schema to use to access the tables. Currently only used
by PostgreSQL

*opt* This takes a hash reference and contains the standard "DBI"
options such as *PrintError*, *RaiseError*, *AutoCommit*,
etc

*conf_file* or *DB_CON_FILE*
This is used to specify a json connection configuration
file. It can also provided via the environment variable
*DB_CON_FILE*. It has the following structure:

{
"database": "some_database",
"host": "db.example.com",
"login": "sql_joe",
"passwd": "some password",
"driver": "Pg",
"schema": "warehouse",
"opt":
{
"RaiseError": false,
"PrintError": true,
"AutoCommit": true
}
}

Alternatively, it can contain connections parameters for
multiple databases and drivers, such as:

{
"databases": [
{
"database": "some_database",
"host": "db.example.com",
"port": 5432,
"login": "sql_joe",
"passwd": "some password",
"driver": "Pg",
"schema": "warehouse",
"opt":
{
"RaiseError": false,
"PrintError": true,
"AutoCommit": true
}
},
{
"database": "other_database",
"host": "db.example2.com",
"login": "sql_bob",
"passwd": "other password",
"driver": "mysql",
},
{
"database": "/path/to/my/database.sqlite",
"driver": "SQLite",
}
]
}

*uri* or *DB_CON_URI*
This is used to specify an uri to contain all the connection
parameters for one database connection. It can also provided
via the environment variable *DB_CON_URI*. For example:

http://db.example.com:5432?database=some_database&login=sql_joe&passwd=some%020password&driver=Pg&schema=warehouse&&opt=%7B%22RaiseError%22%3A+false%2C+%22PrintError%22%3Atrue%2C+%22AutoCommit%22%3Atrue%7D

Here the *opt* parameter is passed as a json string, for
example:

{"RaiseError": false, "PrintError":true, "AutoCommit":true}

METHODS
clear()
Reset error message.

debug( [ 0 | 1 ] )
Toggle debug mode on/off

error( [ $string ] )
Get set error message. If an error message is provided, error will
pass it to warn.

get( $parameter )
Get object parameter.

message( $string )
Provided a multi line string, message will display it on the STDERR
if either *verbose* or *debug* mode is on.

verbose()
Toggle verbose mode on/off

alias( %parameters )
Get/set alias for table fields in SELECT queries. The hash provided
thus contain a list of field => alias pairs.

as_string()
Return the sql query as a string.

avoid( [ @fields | \@fields ] )
Set the provided list of table fields to avoid when returning the
query result. The list of fields can be provided either as an array
of a reference to an array.

attribute( $name | %names )
Sets or get the value of database connection parameters.

If only one argument is provided, returns its value. If multiple
arguments in a form of pair => value are provided, it sets the
corresponding database parameters.

The authorised parameters are:

*Warn* Can be overridden.

*Active*
Read-only.

*Kids* Read-only.

*ActiveKids*
Read-only.

*CachedKids*
Read-only.

*InactiveDestroy*
Can be overridden.

*PrintError*
Can be overridden.

*RaiseError*
Can be overridden.

*ChopBlanks*
Can be overridden.

*LongReadLen*
Can be overridden.

*LongTruncOk*
Can be overridden.

*AutoCommit*
Can be overridden.

*Name* Read-only.

*RowCacheSize*
Read-only.

*NUM_OF_FIELDS*
Read-only.

*NUM_OF_PARAMS*
Read-only.

*NAME* Read-only.

*TYPE* Read-only.

*PRECISION*
Read-only.

*SCALE* Read-only.

*NULLABLE*
Read-only.

*CursorName*
Read-only.

*Statement*
Read-only.

*RowsInCache*
Read-only.

available_drivers()
Return the list of available drivers.

bind( [ @values ] )
If no values to bind to the underlying query is provided, bind
simply activate the bind value feature.

If values are provided, they are allocated to the statement object
and will be applied when the query will be executed.

Example:

$dbh->bind()
## or
$dbh->bind->where( "something" )
## or
$dbh->bind->select->fetchrow_hashref()
## and then later
$dbh->bind( 'thingy' )->select->fetchrow_hashref()

cache()
Activate caching.

$tbl->cache->select->fetchrow_hashref();

check_driver()
Check that the driver set in *$SQL_DRIVER* in ~/etc/common.cfg is
indeed available.

It does this by calling available_drivers.

copy( [ \%values | %values )
Provided with either a reference to an hash or an hash of key =>
value pairs, copy will first execute a select statement on the table
object, then fetch the row of data, then replace the key-value pair
in the result by the ones provided, and finally will perform an
insert.

Return false if no data to copy were provided, otherwise it always
returns true.

create_table( @parameters )
The idea is to create a table with the givern parameters.

This is currently heavily designed to work for PoPList. It needs to
be rewritten.

data_sources( [ %options ] )
Given an optional list of options, this return the data source of
the database handler.

data_type( [ \@types | @types ] )
Given a reference to an array or an array of data type, data_type
will check their availability in the database driver.

If nothing found, it return an empty list in list context, or undef
in scalar context.

If something was found, it returns a hash in list context or a
reference to a hash in list context.

database()
Return the name of the current database.

delete()
delete will format a delete query based on previously set
parameters, such as where.

delete will refuse to execute a query without a where condition. To
achieve this, one must prepare the delete query on his/her own by
using the do method and passing the sql query directly.

$tbl->where( "login" => "jack" );
$tbl->limit( 1 );
my $rows_affected = $tbl->delete();
## or passing the where condition directly to delete
my $sth = $tbl->delete( "login" => "jack" );

disconnect()
Disconnect from database. Returns the return code.

my $rc = $dbh->disconnect;

do( $sql_query, [ \%attributes, \@bind_values ] )
Execute a sql query directly passed with possible attributes and
values to bind.

The attributes list will be used to prepare the query and the bind
values will be used when executing the query.

It returns the statement handler or the number of rows affected.

Example:

$rc = $dbh->do( $statement ) || die( $dbh->errstr );
$rc = $dbh->do( $statement, \%attr ) || die( $dbh->errstr );
$rv = $dbh->do( $statement, \%attr, @bind_values ) || die( $dbh->errstr );
my $rows_deleted = $dbh->do(
q{
DELETE FROM table WHERE status = ?
}, undef(), 'DONE' ) || die( $dbh->errstr );

enhance( [ @value ] )
Toggle the enhance mode on/off.

When on, the functions *from_unixtime* and *unix_timestamp* will be
used on date/time field to translate from and to unix time
seamlessly.

err()
Get the currently set error.

errno()
Is just an alias for err.

errmesg()
Is just an alias for errstr.

errstr()
Get the currently set error string.

fatal( [ 1 | 0 ] )
Toggles fatal mode on/off.

from_unixtime( [ @fields | \@fields ] )
Set the list of fields that are to be treated as unix time and
converted accordingly after the sql query is executed.

It returns the list of fields in list context or a reference to an
array in scalar context.

format_statement( [ \@data, \@order, $table ] )
Format the sql statement.

In list context, it returns 2 strings: one comma-separated list of
fields and one comma-separated list of values. In scalar context, it
only returns a comma-separated string of fields.

format_update( \@data | \%data | %data | @data )
Formats update query based on the following arguments provided:

*data* An array of key-value pairs to be used in the update query.
This array can be provided as the prime argument as a
reference to an array, an array, or as the *data* element of
a hash or a reference to a hash provided.

Why an array if eventually we build a list of key-value
pair? Because the order of the fields may be important, and
if the key-value pair list is provided, format_update honors
the order in which the fields are provided.

format_update will then iterate through each field-value pair, and
perform some work:

If the field being reviewed was provided to from_unixtime, then
format_update will enclose it in the function FROM_UNIXTIME() as in:

FROM_UNIXTIME(field_name)

If the the given value is a reference to a scalar, it will be used
as-is, ie. it will not be enclosed in quotes or anything. This is
useful if you want to control which function to use around that
field.

If the given value is another field or looks like a function having
parenthesis, or if the value is a question mark, the value will be
used as-is.

If bind is off, the value will be escaped and the pair field='value'
created.

If the field is a SET data type and the value is a number, the value
will be used as-is without surrounding single quote.

If bind is enabled, a question mark will be used as the value and
the original value will be saved as value to bind upon executing the
query.

Finally, otherwise the value is escaped and surrounded by single
quotes.

format_update returns a string representing the comma-separated list
of fields that will be used.

getdefault( %default_values )
Does some preparation work such as :

1 the date/time field to use the FROM_UNIXTIME and
UNIX_TIMESTAMP functions

2 removing from the query the fields to avoid, ie the ones set
with the avoid method.

3 set the fields alias based on the information provided with
the alias method.

4 if a field last_name and first_name exist, it will also
create an alias *name* based on the concatenation of the 2.

5 it will set the default values provided. This is used for
UPDATE queries.

It returns a new DB::Object::Tables object with all the data
prepared within.

group( @fields | \@fields )
Format the group by portion of the query.

It returns an empty list in list context of undef in scalar context
if no group by clause was build. Otherwise, it returns the value of
the group by clause as a string in list context and the full group
by clause in scalar context.

In list context, it returns: $group_by

In scalar context, it returns: GROUP BY $group_by

insert( DB::Object::Statement SELECT object, \%key_value | %key_value )
Prepares an INSERT query using the field-value pairs provided.

If a DB::Object::Statement object is provided as first argument, it
will considered as a SELECT query to be used in the INSERT query, as
in: INSERT INTO my table SELECT FROM another_table

Otherwise, insert will build the query based on the fields provided.

In scalar context, it returns the result of execute and in list
context, it returns the statement object.

last_insert_id()
Get the id of the primary key from the last insert.

limit( [ END, [ START, END ] ] )
Set or get the limit for the future statement.

If only one argument is provided, it is assumed to be the end limit.
If 2 are provided, they wil be the start and end.

It returns a list of the start and end limit in list context, and
the string of the LIMIT in scalar context, such as: LIMIT 1, 10

local( %params | \%params )
Not sure what it does. I forgot.

lock( $lock_id, [ $timeout ] )
Set a lock using a lock identifier and a timeout. By default the
timeout is 2 seconds.

If the lock failed (NULL), it returns undef(), otherwise, it returns
the return value.

no_bind()
When invoked, no_bind will change any preparation made so far for
caching the query with bind parameters, and instead substitute the
value in lieu of the question mark placeholder.

no_cache()
Disable caching of queries.

order()
Prepares the ORDER BY clause and returns the value of the clause in
list context or the ORDER BY clause in full in scalar context, ie.
"ORDER BY $clause"

param( $param | %params )
If only a single parameter is provided, its value is return. If a
list of parameters is provided they are set accordingly using the
"SET" sql command.

Supported parameters are:

SQL_AUTO_IS_NULL
AUTOCOMMIT
SQL_BIG_TABLES
SQL_BIG_SELECTS
SQL_BUFFER_RESULT
SQL_LOW_PRIORITY_UPDATES
SQL_MAX_JOIN_SIZE
SQL_SAFE_MODE
SQL_SELECT_LIMIT
SQL_LOG_OFF
SQL_LOG_UPDATE
TIMESTAMP
INSERT_ID
LAST_INSERT_ID

If unsupported parameters are provided, they are considered to be
private and not passed to the database handler.

It then execute the query and return undef() in case of error.

Otherwise, it returns the object used to call the method.

ping()
Evals a SELECT 1 statement and returns 0 if errors occurred or the
return value.

prepare( $query, \%options )
Prepares the query using the options provided. The options are the
same as the one in DBI prepare method.

It returns a DB::Object::Statement object upon success or undef if
an error occurred. The error can then be retrieved using errstr or
error.

prepare_cached( $query, \%options )
Same as prepare except the query is cached.

query( $query, \%options )
It prepares and executes the given SQL query with the options
provided and return undef() upon error or the statement handler upon
success.

replace( DB::Object::Statement object, [ %data ] )
Just like for the INSERT query, replace takes one optional argument
representing a DB::Object::Statement SELECT object or a list of
field-value pairs.

If a SELECT statement is provided, it will be used to construct a
query of the type of REPLACE INTO mytable SELECT FROM other_table

Otherwise the query will be REPLACE INTO mytable (fields)
VALUES(values)

In scalar context, it execute the query and in list context it
simply returns the statement handler.

reset()
This is used to reset a prepared query to its default values. If a
field is a date/time type, its default value will be set to NOW()

It execute an update with the reseted value and return the number of
affected rows.

reverse( [ true ])
Get or set the reverse mode.

select( [ \$field, \@fields, @fields ] )
Given an optional list of fields to fetch, select prepares a SELECT
query.

If no field was provided, select will use default value where
appropriate like the NOW() for date/time fields.

select calls upon tie, where, group, order, limit and local to build
the query.

In scalar context, it execute the query and return it. In list
context, it just returns the statement handler.

set( $var )
Issues a query to "SET" the given SQL variable.

If any error occurred, undef will be returned and an error set,
otherwise it returns true.

sort()
It toggles sort mode on and consequently disable reverse mode.

stat( [ $type ] )
Issue a SHOW STATUS query and if a particular $type is provided, it
will returns its value if it exists, otherwise it will return undef.

In absence of particular $type provided, it returns the hash list of
values returns or a reference to the hash list in scalar context.

state()
Queries the DBI state and return its value.

table( $table_name )
Given a table name, table will return a DB::Object::Tables object.
The object is cached for re-use.

table_push( $table_name )
Add the given table name to the stack of cached table names.

tables( [ $database ] )
Connects to the database and finds out the list of all available
tables.

Returns undef or empty list in scalar or list context respectively
if no table found.

Otherwise, it returns the list of table in list context or a
reference of it in scalar context.

tables_refresh( [ $database ] )
Rebuild the list of available database table.

Returns the list of table in list context or a reference of it in
scalar context.

tie( [ %fields ] )
If provided a hash or a hash ref, it sets the list of fields and
their corresponding perl variable to bind their values to.

In list context, it returns the list of those field-variable pair,
or a reference to it in scalar context.

unix_timestamp( [ \@fields | @fields ] )
Provided a list of fields or a reference to it, this sets the fields
to be treated for seamless conversion from and to unix time.

unlock( $lock_id )
Given a lock identifier, unlock releases the lock previously set
with lock. It executes the underlying sql command and returns
undef() if the result is NULL or the value returned otherwise.

update( %data | \%data )
Given a list of field-value pairs, update prepares a sql update
query.

It calls upon where and limit as previously set.

It returns undef and sets an error if it failed to prepare the
update statement. In scalar context, it execute the query. In list
context, it simply return the statement handler.

use( $database )
Given a database, it switch to it, but before it checks that the
database exists. If the database is different than the current one,
it sets the *multi_db* parameter, which will have the fields in the
queries be prefixed by their respective database name.

It returns the database handler.

use_cache( [ 0 | 1 ] )
Sets or get the *use_cache* parameter.

use_bind( [ 0 | 1 ] )
Sets or get the *use_cache* parameter.

variables( [ $type ] )
Query the SQL variable $type

It returns a blank string if nothing was found, or the value found.

where( %args )
Build the where clause based on the field-value hash provided.

It returns the where clause in list context or the full where clause
in scalar context, ie "WHERE $clause"

_cache_this( $query )
Provided with a query, this will cache it for future re-use.

It does some check and maintenance job to ensure the cache does not
get too big whenever it exceed the value of $CACHE_SIZE set in the
main config file.

It returns the cached statement as an DB::Object::Statement object.

_clean_statement( \$query | $query )
Given a query string or a reference to it, it cleans the statement
by removing leading and trailing space before and after line breaks.

_cleanup()
Removes object attributes, namely where, selected_fields, group_by,
order_by, limit, alias, avoid, local, and as_string

_make_sth( $package, $hashref )
Given a package name and a hashref, this build a statement object
with all the necessary parameters.

It also sets the query time to the current time with the parameter
*query_time*

It returns an object of the given $package.

_reset_query()
Being called using a statement handler, this reset the object by
removing all the parameters set by various subroutine calls, such as
where, group, order, avoid, limit, etc.

_save_bind( $query_type )
This saves/cache the bin query and return the object used to call
it.

_value2bind( $query, $ref )
Given a sql query and a array reference, _value2bind parse the query
and interpolate values for placeholder (?).

It returns true.

OPERATORS
AND( VALUES )
Given a value, this returns a DB::Object::AND object. You can retrieve
the value with value

This is used by where

my $op = $dbh->AND( login => 'joe', status => 'active' );
## will produce:
WHERE login = 'joe' AND status = 'active'

NOT( VALUES )
Given a value, this returns a DB::Object::NOT object. You can retrieve
the value with value

This is used by where

my $op = $dbh->AND( login => 'joe', status => $dbh->NOT( 'active' ) );
## will produce:
WHERE login = 'joe' AND status != 'active'

OR( VALUES )
Given a value, this returns a DB::Object::OR object. You can retrieve
the value with value

This is used by where

my $op = $dbh->OR( login => 'joe', login => 'john' );
## will produce:
WHERE login = 'joe' OR login = 'john'

COPYRIGHT
Copyright (c) 2019-2020 DEGUEST Pte. Ltd.

CREDITS
Jacques Deguest <[email protected]>

SEE ALSO
DBI, Apache::DBI