NAME

DBIx::DBO::Query - An OO interface to SQL queries and results. Encapsulates an entire query in an object.

SYNOPSIS

# Create a Query object by JOINing 2 tables
my $query = $dbo->query('my_table', 'my_other_table');

# Get the Table objects from the query
my ($table1, $table2) = $query->tables;

# Add a JOIN ON clause
$query->join_on($table1 ** 'login', '=', $table2 ** 'username');

# Find our ancestors, and order by age (oldest first)
$query->where('name', '=', 'Adam');
$query->where('name', '=', 'Eve');
$query->order_by({ COL => 'age', ORDER => 'DESC' });

# New Query using a LEFT JOIN
($query, $table1) = $dbo->query('my_table');
$table2 = $query->join_table('another_table', 'LEFT');
$query->join_on($table1 ** 'parent_id', '=', $table2 ** 'child_id');

# Find those not aged between 20 and 30.
$query->where($table1 ** 'age', '<', 20, FORCE => 'OR'); # Force OR so that we get: (age < 20 OR age > 30)
$query->where($table1 ** 'age', '>', 30, FORCE => 'OR'); # instead of the default: (age < 20 AND age > 30)

METHODS

`reset`

$query->reset;

Reset the query, start over with a clean slate.

NB. This will not remove the JOINs or JOIN ON clauses.

`tables`

Return a list of DBIx::DBO::Table objects for this query.

`show`

$query->show(@columns);
$query->show($table1 ** 'id', {FUNC => 'UCASE(?)', COL => 'name', AS => 'NAME'}, ...

Specify which columns to show as an array. If the array is empty all columns will be shown.

`join_table`

$query->join_table($table, $join_type);
$query->join_table([$schema, $table], $join_type);
$query->join_table($table_object, $join_type);

Join a table onto the query, creating a DBIx::DBO::Table object if needed. This will perform a comma (", ") join unless $join_type is specified.

Valid join types are any accepted by the DB. Eg: 'JOIN', 'LEFT', 'RIGHT', undef (for comma join), 'INNER', 'OUTER', ...

Returns the Table object.

`join_on`

$query->join_on($table_object, $expression1, $operator, $expression2);
$query->join_on($table2, $table1 ** 'id', '=', $table2 ** 'id');

Join tables on a specific WHERE clause. The first argument is the table object being joined onto. Then a JOIN ON condition follows, which uses the same arguments as "where".

`where`

Restrict the query with the condition specified (WHERE clause).

$query->where($expression1, $operator, $expression2);
$query->where($table1 ** 'id', '=', $table2 ** 'id');

$operator is one of: '=', '<', '>', 'IN', 'NOT IN', 'BETWEEN', 'NOT BETWEEN', ...

$expressions can be any of the following:

A scalar value: 123 or 'hello' (or for $expression1 a column name: 'id')
A scalar reference: \"22 * 3" (These are passed unquoted in the SQL statement!)
An array reference: [1, 3, 5] (Used with IN and BETWEEN etc)
A Column object: $table ** 'id' or $table-column('id')>
A hash reference: (Described below)

For a more complex where expression it can be passed as a hash reference. Possibly containing scalars, arrays or Column objects.

$query->where('name', '=', { FUNC => 'COALESCE(?,?)', VAL => [$name, 'Unknown'] });
$query->where('string', '=', { FUNC => "CONCAT('Mr. ',?)", COL => 'name' });

The keys to the hash in a complex expression are:

VAL => A scalar, scalar reference or an array reference.
COL => The name of a column or a Column object.
AS => An alias name.
FUNC => A string to be inserted into the SQL, possibly containing "?" placeholders.
ORDER => To order by a column. (Used only in group_by and order_by)

Multiple where expressions are combined cleverly using the preferred aggregator 'AND' (unless open_bracket was used to change this). So that when you add where expressions to the query, they will be 'AND'ed together. However some expressions will automatically be 'OR'ed instead where this makes sense, Eg:

$query->where('id', '=', 5);
$query->where('id', '=', 7);
$query->where(...
# Produces: WHERE ("id" = 5 OR "id" = 7) AND ...

`unwhere`

$query->unwhere();
$query->unwhere($column);
$query->unwhere($table1 ** 'id');

Removes all previously added where() restrictions for a column. If no column is provided, ALL where() restrictions are removed.

`open_bracket`, `close_bracket`

$query->open_bracket('OR');
$query->where( ...
$query->where( ...
$query->close_bracket;

Used to group where expressions together in parenthesis using either 'AND' or 'OR' as the preferred aggregator. All the where calls made between open_bracket and close_bracket will be inside the parenthesis.

Without any parenthesis 'AND' is the preferred aggregator.

`group_by`

$query->group_by('column', ...);
$query->group_by($table ** 'column', ...);
$query->group_by({ COL => $table ** 'column', ORDER => 'DESC' }, ...);

Group the results by the column(s) listed. This will replace the GROUP BY clause. To remove the GROUP BY clause simply call group_by without any columns.

`order_by`

$query->order_by('column', ...);
$query->order_by($table ** 'column', ...);
$query->order_by({ COL => $table ** 'column', ORDER => 'DESC' }, ...);

Order the results by the column(s) listed. This will replace the ORDER BY clause. To remove the ORDER BY clause simply call order_by without any columns.

`limit`

$query->limit;
$query->limit($rows);
$query->limit($rows, $offset);

Limit the maximum number of rows returned to $rows, optionally skipping the first $offset rows. When called without arguments or if $rows is undefined, the limit is removed.

`arrayref`

$query->arrayref;
$query->arrayref(\%attr);

Run the query using DBI->selectall_arrayref which returns the result as an arrayref. You can specify a slice by including a 'Slice' or 'Columns' attribute in %attr - See DBI->selectall_arrayref.

`hashref`

$query->hashref($key_field);
$query->hashref($key_field, \%attr);

Run the query using DBI->selectall_hashref which returns the result as an hashref. $key_field defines which column, or columns, are used as keys in the returned hash.

`col_arrayref`

$query->col_arrayref;
$query->col_arrayref(\%attr);

Run the query using DBI->selectcol_arrayref which returns the result as an arrayref of the values of each row in one array. By default it pushes all the columns requested by the "show" method onto the result array (this differs from the DBI). Or to specify which columns to include in the result use the 'Columns' attribute in %attr - see DBI->selectcol_arrayref.

`fetch`

my $row = $query->fetch;

Fetch the next row from the query. This will run/rerun the query if needed.

Returns a DBIx::DBO::Row object or undefined if there are no more rows.

`row`

my $row = $query->row;

Returns the DBIx::DBO::Row object for the current row from the query or an empty DBIx::DBO::Row object if there is no current row.

`run`

$query->run;

Run/rerun the query. This is called automatically before fetching the first row.

`rows`

my $row_count = $query->rows;

Count the number of rows returned. Returns undefined if there is an error or the number is unknown.

`count_rows`

my $row_count = $query->count_rows;

Count the number of rows that would be returned. Returns undefined if there is an error.

`found_rows`

$query->config(CalcFoundRows => 1); # Only applicable to MySQL
my $total_rows = $query->found_rows;

Return the number of rows that would have been returned if there was no limit clause. Before runnning the query the CalcFoundRows config option can be enabled for improved performance on supported databases.

Returns undefined if there is an error or is unable to determine the number of found rows.

`sql`

my $sql = $query->sql;

Returns the SQL query statement string.

`sth`

my $sth = $query->sth;

Reutrns the DBI statement handle from the query. This will run/rerun the query if needed.

`finish`

$query->finish;

Calls DBI->finish on the statement handle, if it's active.

Common Methods

These methods are accessible from all DBIx::DBO* objects.

`dbh`

The read-write DBI handle.

`rdbh`

The read-only DBI handle, or if there is no read-only connection, the read-write DBI handle.

`do`

$dbo->do($statement)         or die $dbo->dbh->errstr;
$dbo->do($statement, \%attr) or die $dbo->dbh->errstr;
$dbo->do($statement, \%attr, @bind_values) or die ...

This provides access to DBI->do method. It defaults to using the read-write DBI handle.

`config`

$query_setting = $dbo->config($option);
$dbo->config($option => $query_setting);

Get or set this Query object's config settings. When setting an option, the previous value is returned.

TODO LIST

Better explanation of subclassing, to create easy to use query objects.
Better explanation of how to construct complex queries.

This module is currently still in development (including the documentation), but I will be adding to/completing it in the near future.
Add DISTINCT and COLLATE functionality.
Possibly add open_join_on_bracket for adding parentheses in the JOIN ON clause, but I'm not sure if this would ever be useful.

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NAME

SYNOPSIS

METHODS

reset

tables

show

join_table

join_on

where

unwhere

open_bracket, close_bracket

group_by

order_by

limit

arrayref

hashref

col_arrayref

fetch

row

run

rows

count_rows

found_rows

sql

sth

finish