Provided by: librose-db-object-perl_0.797-1_all bug

NAME

       Rose::DB::Object::QueryBuilder - Build SQL queries on behalf of Rose::DB::Object::Manager.

SYNOPSIS

           use Rose::DB::Object::QueryBuilder qw(build_select);

           # Build simple query
           $sql = build_select
           (
             dbh     => $dbh,
             select  => 'COUNT(*)',
             tables  => [ 'articles' ],
             columns => { articles => [ qw(id category type title date) ] },
             query   =>
             [
               category => [ 'sports', 'science' ],
               type     => 'news',
               title    => { like => [ '%million%',
                                       '%resident%' ] },
             ],
             query_is_sql => 1);

           $sth = $dbh->prepare($sql);
           $sth->execute;
           $count = $sth->fetchrow_array;

           ...

           # Return query with placeholders, plus bind values
           ($sql, $bind) = build_select
           (
             dbh     => $dbh,
             tables  => [ 'articles' ],
             columns => { articles => [ qw(id category type title date) ] },
             query   =>
             [
               category => [ 'sports', 'science' ],
               type     => 'news',
               title    => { like => [ '%million%',
                                       '%resident%' ] },
             ],
             query_is_sql => 1,
             sort_by      => 'title DESC, category',
             limit        => 5);

           $sth = $dbh->prepare($sql);
           $sth->execute(@$bind);

           while($row = $sth->fetchrow_hashref) { ... }

           ...

           # Coerce query values into the right format
           ($sql, $bind) = build_select
           (
             db      => $db,
             tables  => [ 'articles' ],
             columns => { articles => [ qw(id category type title date) ] },
             classes => { articles => 'Article' },
             query   =>
             [
               type     => 'news',
               date     => { lt => 'now' },
               date     => { gt => DateTime->new(...) },
             ],
             sort_by      => 'title DESC, category',
             limit        => 5);

           $sth = $dbh->prepare($sql);
           $sth->execute(@$bind);

DESCRIPTION

       Rose::DB::Object::QueryBuilder is used to build SQL queries, primarily in service of the
       Rose::DB::Object::Manager class.  It (optionally) exports two functions: build_select()
       and build_where_clause().

FUNCTIONS

       build_select PARAMS
           Returns an SQL "select" query string (in scalar context) or an SQL "select" query
           string with placeholders and a reference to an array of bind values (in list context)
           constructed based on PARAMS.  Valid PARAMS are described below.

           clauses CLAUSES
               A reference to an array of extra SQL clauses to add to the "WHERE" portion of the
               query string.  This is the obligatory "escape hatch" for clauses that are not
               supported by arguments to the query parameter.

           columns HASHREF
               A reference to a hash keyed by table name, each of which points to a reference to
               an array of the names of the columns in that table.  Example:

                   $sql = build_select(columns =>
                                       {
                                         table1 => [ 'col1', 'col2', ... ],
                                         table2 => [ 'col1', 'col2', ... ],
                                         ...
                                       });

               This argument is required.

           db DB
               A Rose::DB-derived object.  This argument is required if query_is_sql is false or
               omitted.

           dbh DBH
               A DBI database handle already connected to the correct database.  If this argument
               is omitted, an attempt will be made to extract a database handle from the db
               argument.  If this fails, or if there is no db argument, a fatal error will occur.

           group_by CLAUSE
               A fully formed SQL "GROUP BY ..." clause, sans the words "GROUP BY", or a
               reference to an array of strings to be joined with a comma and appended to the
               "GROUP BY" clause.

           limit NUMBER
               A number to use in the "LIMIT ..." clause.

           logic LOGIC
               A string indicating the logic that will be used to join the statements in the
               WHERE clause.  Valid values for LOGIC are "AND" and "OR".  If omitted, it defaults
               to "AND".

           pretty BOOL
               If true, the SQL returned will have slightly nicer formatting.

           query PARAMS
               The query parameters, passed as a reference to an array of name/value pairs,
               scalar references, or array references.  PARAMS may include an arbitrary list of
               selection parameters used to modify the "WHERE" clause of the SQL select
               statement.  Any query parameter that is not in one of the forms described below
               will cause a fatal error.

               Valid selection parameters are described below, along with the SQL clause they add
               to the select statement.

               Simple equality:

                   'NAME'  => "foo"        # COLUMN = 'foo'
                   '!NAME' => "foo"        # NOT(COLUMN = 'foo')

                   'NAME'  => [ "a", "b" ] # COLUMN IN ('a', 'b')
                   '!NAME' => [ "a", "b" ] # COLUMN NOT(IN ('a', 'b'))

               Is/is not null:

                   'NAME'  => undef            # COLUMN IS NULL
                   '!NAME' => undef            # COLUMN IS NOT NULL

                   'NAME'  => { eq => undef }  # COLUMN IS NULL
                   'NAME'  => { ne => undef }  # COLUMN IS NOT NULL

               Comparisons:

                   NAME => { OP => "foo" } # COLUMN OP 'foo'

                   # (COLUMN OP 'foo' OR COLUMN OP 'goo')
                   NAME => { OP => [ "foo", "goo" ] }

               "OP" can be any of the following:

                   OP                  SQL operator
                   -------------       ------------
                   similar             SIMILAR TO
                   match               ~
                   imatch              ~*
                   regex, regexp       REGEXP
                   like                LIKE
                   ilike               ILIKE
                   rlike               RLIKE
                   is                  IS
                   is_not              IS NOT
                   ne                  <>
                   eq                  =
                   lt                  <
                   gt                  >
                   le                  <=
                   ge                  >=

               Ranges:

                   NAME => { between => [ 1, 99 ] } # COLUMN BETWEEN 1 AND 99

                   NAME => { gt_lt => [ 1, 99 ] } # (COLUMN > 1 AND < 99)
                   NAME => { gt_le => [ 1, 99 ] } # (COLUMN > 1 AND <= 99)
                   NAME => { ge_lt => [ 1, 99 ] } # (COLUMN >= 1 AND < 99)
                   NAME => { ge_le => [ 1, 99 ] } # (COLUMN >= 1 AND <= 99)

               If a value is a reference to a scalar, that scalar is "inlined" without any
               quoting.

                   'NAME' => \"foo"        # COLUMN = foo
                   'NAME' => [ "a", \"b" ] # COLUMN IN ('a', b)

               Undefined values are translated to the keyword NULL when included in a multi-value
               comparison.

                   'NAME' => [ "a", undef ] # COLUMN IN ('a', NULL)

               Set operations:

                   ### Informix (default) ###

                   # A IN COLUMN
                   'NAME' => { in_set => 'A' }

                   # NOT(A IN COLUMN)
                   '!NAME' => { in_set => 'A' }

                   # (A IN COLUMN OR B IN COLUMN)
                   'NAME' => { in_set => [ 'A', 'B'] }
                   'NAME' => { any_in_set => [ 'A', 'B'] }

                   # NOT(A IN COLUMN) AND NOT(B IN COLUMN)
                   '!NAME' => { in_set => [ 'A', 'B'] }
                   '!NAME' => { any_in_set => [ 'A', 'B'] }

                   # (A IN COLUMN AND B IN COLUMN)
                   'NAME' => { all_in_set => [ 'A', 'B'] }

                   # NOT(A IN COLUMN AND B IN COLUMN)
                   '!NAME' => { all_in_set => [ 'A', 'B'] }

                   ### MySQL (requires db parameter)  ###

                   # FIND_IN_SET(A, COLUMN) > 0
                   'NAME' => { in_set => 'A' }

                   # NOT(FIND_IN_SET(A, COLUMN) > 0)
                   '!NAME' => { in_set => 'A' }

                   # (FIND_IN_SET(A, COLUMN) > 0 OR FIND_IN_SET(B, COLUMN) > 0)
                   'NAME' => { in_set => [ 'A', 'B'] }
                   'NAME' => { any_in_set => [ 'A', 'B'] }

                   # NOT(FIND_IN_SET(A, COLUMN) > 0) AND NOT(FIND_IN_SET(B, COLUMN) > 0)
                   '!NAME' => { in_set => [ 'A', 'B'] }
                   '!NAME' => { any_in_set => [ 'A', 'B'] }

                   # (FIND_IN_SET(A, COLUMN) > 0 AND FIND_IN_SET(B, COLUMN) > 0)
                   'NAME' => { all_in_set => [ 'A', 'B'] }

                   # NOT(FIND_IN_SET(A, COLUMN) > 0 AND FIND_IN_SET(B, COLUMN) > 0)
                   '!NAME' => { all_in_set => [ 'A', 'B'] }

               Array operations:

                   # A = ANY(COLUMN)
                   'NAME' => { in_array => 'A' }

                   # NOT(A = ANY(COLUMN))
                   '!NAME' => { in_array => 'A' }

                   # (A = ANY(COLUMN) OR B = ANY(COLUMN))
                   'NAME' => { in_array => [ 'A', 'B'] }
                   'NAME' => { any_in_array => [ 'A', 'B'] }

                   # NOT(A = ANY(COLUMN) OR B = ANY(COLUMN))
                   '!NAME' => { in_array => [ 'A', 'B'] }
                   '!NAME' => { any_in_array => [ 'A', 'B'] }

                   # (A = ANY(COLUMN) AND B = ANY(COLUMN))
                   'NAME' => { all_in_array => [ 'A', 'B'] }

                   # NOT(A = ANY(COLUMN) AND B = ANY(COLUMN))
                   '!NAME' => { all_in_array => [ 'A', 'B'] }

               PostgreSQL ltree operations:

                   OP                  SQL operator
                   -------------       ------------
                   ltree_ancestor      @>
                   ltree_descendant    <@
                   ltree_query         ~
                   ltree_ltxtquery     @
                   ltree_concat        ||

               Any of the operations described above can have "_sql" appended to indicate that
               the corresponding values are to be "inlined" (i.e., included in the SQL query as-
               is, with no quoting of any kind).  This is useful for comparing two columns.  For
               example, this query:

                   query => [ legs => { gt_sql => 'eyes' } ]

               would produce this SQL:

                   SELECT ... FROM animals WHERE legs > eyes

               where "legs" and "eyes" are both left unquoted.

               The same NAME string may be repeated multiple times.  (This is the primary reason
               that the query is a reference to an array of name/value pairs, rather than a
               reference to a hash, which would only allow each NAME once.)  Example:

                   query =>
                   [
                     age => { gt => 10 },
                     age => { lt => 20 },
                   ]

               The string "NAME" can take many forms, each of which eventually resolves to a
               database column (COLUMN in the examples above).

               Literal SQL can be included by providing a reference to a scalar:

                   \'mycol > 123'

               To use placeholders and bind values, pass a reference to an array containing a
               scalar reference to the literal SQL with placeholders as the first item, followed
               by a list of values to bind:

                   [ \'mycol > ?' => 123 ]

               "column"
                   A bare column name.  If the query includes more than one table, the column
                   name may be ambiguous if it appears in two or more tables.  In that case, a
                   fatal error will occur.  To solve this, use one of the less ambiguous forms
                   below.

               "table.column"
                   A column name and a table name joined by a dot.  This is the "fully qualified"
                   column name.

               "tN.column"
                   A column name and a table alias joined by a dot.  The table alias is in the
                   form "tN", where "N" is a number starting from 1.  See the documentation for
                   tables parameter below to learn how table aliases are assigned to tables.

               Any of the above prefixed with "!"
                   This indicates the negation of the specified condition.

               If query_is_sql is false or omitted, then NAME can also take on these additional
               forms:

               "method"
                   A get_set column method name from a Rose::DB::Object-derived class fronting
                   one of the tables being queried.  There may be ambiguity here if the same
                   method name is defined on more than one of the the classes involved in the
                   query.  In such a case, the method will be mapped to the first
                   Rose::DB::Object-derived class that contains a method by that name, considered
                   in the order that the tables are provided in the tables parameter.

               "!method"
                   This indicates the negation of the specified condition.

               Un-prefixed column or method names that are ambiguous (i.e., exist in more than
               one of the tables being queried) are considered to be part of the primary table
               ("t1").

               Finally, in the case of apparently intractable ambiguity, like when a table name
               is the same as another table's alias, remember that you can always use the
               "tn_"-prefixed column name aliases, which are unique within a given query.

               All of these clauses are joined by logic (default: "AND") in the final query.
               Example:

                   $sql = build_select
                   (
                     dbh     => $dbh,
                     select  => 'id, title',
                     tables  => [ 'articles' ],
                     columns => { articles => [ qw(id category type title) ] },
                     query   =>
                     [
                       category => [ 'sports', 'science' ],
                       type     => 'news',
                       title    => { like => [ '%million%',
                                               '%resident%' ] },
                     ],
                     query_is_sql => 1);

               The above returns an SQL statement something like this:

                   SELECT id, title FROM articles WHERE
                     category IN ('sports', 'science')
                     AND
                     type = 'news'
                     AND
                     (title LIKE '%million%' OR title LIKE '%resident%')
                   LIMIT 5

               Nested boolean logic is possible using the special keywords "and" and "or" (case
               insensitive).  Example:

                   $sql = build_select
                   (
                     dbh     => $dbh,
                     select  => 'id, title',
                     tables  => [ 'articles' ],
                     columns => { articles => [ qw(id category type title) ] },
                     query   =>
                     [
                       or =>
                       [
                         and => [ category => undef, type => 'aux' ],
                         category => [ 'sports', 'science' ],
                       ],
                       type     => 'news',
                       title    => { like => [ '%million%',
                                               '%resident%' ] },
                     ],
                     query_is_sql => 1);

               which returns an SQL statement something like this:

                   SELECT id, title FROM articles WHERE
                     (
                       (
                         category IS NULL AND
                         type = 'aux'
                       )
                       OR category IN ('sports', 'science')
                     )
                     AND
                     type = 'news'
                     AND
                     (title LIKE '%million%' OR title LIKE '%resident%')

               The "and" and "or" keywords can be used multiple times within a query (just like
               all other NAME specifiers described earlier) and can be arbitrarily nested.

               If you have a column named "and" or "or", you'll have to use the fully-qualified
               (table.column) or alias-qualified (tN.column) forms in order to address that
               column.

               If query_is_sql is false or omitted, all of the parameter values are passed
               through the "parse_value()" and "format_value()" methods of their corresponding
               Rose::DB::Object::Metadata::Column-dervied column objects.

               If a column object returns true from its manager_uses_method() method, then its
               parameter value is passed through the corresponding Rose::DB::Object-derived
               object method instead.

               Example:

                   $dt = DateTime->new(year => 2001, month => 1, day => 31);

                   $sql = build_select
                   (
                     db      => $db,
                     select  => 'id, category',
                     tables  => [ 'articles' ],
                     columns => { articles => [ qw(id category type date) ] },
                     classes => { articles => 'Article' },
                     query   =>
                     [
                       type  => 'news',
                       date  => { lt => '12/25/2003 8pm' },
                       date  => { gt => $dt },
                     ],
                     sort_by => 'id DESC, category',
                     limit   => 5);

               The above returns an SQL statement something like this:

                   SELECT id, category FROM articles WHERE
                     type = 'news'
                     AND
                     date < '2003-12-25 20:00:00'
                     AND
                     date > '2001-01-31 00:00:00'
                   ORDER BY id DESC, category
                   LIMIT 5

               Finally, here's an example using more than one table:

                   $dt = DateTime->new(year => 2001, month => 1, day => 31);

                   $sql = build_select
                   (
                     db      => $db,
                     tables  => [ 'articles', 'categories' ],
                     columns =>
                     {
                       articles   => [ qw(id name category_id date) ],
                       categories => [ qw(id name description) ],
                     },
                     classes =>
                     {
                       articles   => 'Article',
                       categories => 'Category',
                     },
                     query   =>
                     [
                       '!t1.name' => { like => '%foo%' },
                       t2.name    => 'news',
                       date       => { lt => '12/25/2003 8pm' },
                       date       => { gt => $dt },
                     ],
                     clauses =>
                     [
                       't1.category_id = t2.id',
                     ],
                     sort_by      => 'articles.name DESC, t2.name',
                     limit        => 5);

               The above returns an SQL statement something like this:

                   SELECT
                     t1.id,
                     t1.name,
                     t1.category_id,
                     t1.date,
                     t2.id,
                     t2.name,
                     t2.description
                   FROM
                     articles   t1,
                     categories t2
                   WHERE
                     t1.category_id = t2.id
                     AND
                     NOT(t1.name LIKE '%foo%')
                     AND
                     t2.name = 'news'
                     AND
                     t1.date < '2003-12-25 20:00:00'
                     AND
                     t1.date > '2001-01-31 00:00:00'
                   ORDER BY articles.name DESC, t2.name
                   LIMIT 5

           query_is_sql BOOL
               If omitted, this boolean flag is false.  If true, then the values of the query
               parameters are taken as literal strings that are suitable for direct use in SQL
               queries.  Example:

                   $sql = build_select
                   (
                     query_is_sql => 1,
                     query =>
                     [
                       date => { lt => '2003-12-25 20:00:00' },
                     ],
                     ...
                   );

               Here the date value "2003-12-25 20:00:00" must be in the format that the current
               database expects for columns of that data type.

               But if query_is_sql is false or omitted, then any query value that can be handled
               by the Rose::DB::Object-derived object method that services the corresponding
               database column is valid.  (Note that this is only possible when this method is
               called from one of the built-in Rose::DB::Object::Manager methods, e.g.,
               get_objects().)

               Example:

                   $dt = DateTime->new(year => 2001, month => 1, day => 31);

                   $sql = build_select
                   (
                     query =>
                     [
                       date => { gt => $dt },
                       date => { lt => '12/25/2003 8pm' },
                     ],
                     ...
                   );

               Here a DateTime object and a loosely formatted date are passed as values.
               Provided the Rose::DB::Object-derived object method that services the "date"
               column can handle such values, they will be parsed and formatted as appropriate
               for the current database.

               The advantage of this approach is that the query values do not have to be so
               rigorously specified, nor do they have to be in a database-specific format.

               The disadvantage is that all of this parsing and formatting is done for every
               query value, and that adds additional overhead to each call.

               Usually, this overhead is dwarfed by the time required for the database to service
               the query, and, perhaps more importantly, the reduced maintenance headache and
               busywork required to properly format all query values.

           select COLUMNS
               The names of the columns to select from the table.  COLUMNS may be a string of
               comma-separated column names, or a reference to an array of column names.  If this
               parameter is omitted, it defaults to all of the columns in all of the tables
               participating in the query (according to the value of the columns argument).

           sort_by [ CLAUSE | ARRAYREF ]
               A fully formed SQL "ORDER BY ..." clause, sans the words "ORDER BY", or a
               reference to an array of strings to be joined with a comma and appended to the
               "ORDER BY" clause.

               If an item in the referenced array is itself a reference to a scalar, then that
               item will be dereferenced and passed through unmodified.

           tables TABLES
               A reference to an array of table names.  This argument is required.  A fatal error
               will occur if it is omitted.

               If more than one table is in the list, then each table is aliased to "tN", where N
               is an ascending number starting with 1.  The tables are numbered according to
               their order in TABLES.  Example:

                   $sql = build_select(tables => [ 'foo', 'bar', 'baz' ], ...);

                   print $sql;

                   # SELECT ... FROM
                   #   foo AS t1,
                   #   bar AS t2,
                   #   baz AS t3
                   # ...

               Furthermore, if there is no explicit value for the select parameter and if the
               unique_aliases parameter is set to true, then each selected column is aliased with
               a "tN_" prefix in a multi-table query.  Example:

                   SELECT
                     t1.id    AS t1_id,
                     t1.name  AS t1_name,
                     t2.id    AS t2_id,
                     t2.name  AS t2_name
                   FROM
                     foo AS t1,
                     bar AS t2
                   WHERE
                     ...

               These unique aliases provide a technique of last resort for unambiguously
               addressing a column in a query clause.

           unique_aliases BOOL
               If true, then each selected column will be given a unique alias by prefixing it
               with its table alias and an underscore.  The default value is false.  See the
               documentation for the tables parameter above for an example.

       build_where_clause PARAMS
           This works the same as the build_select() function, except that it only returns the
           "WHERE" clause of the SQL query, sans the word "WHERE" and prefixed with a single
           space.

AUTHOR

       John C. Siracusa (siracusa@gmail.com)

LICENSE

       Copyright (c) 2010 by John C. Siracusa.  All rights reserved.  This program is free
       software; you can redistribute it and/or modify it under the same terms as Perl itself.