1Data::ObjectDriver::SQLU(s3eprm)Contributed Perl DocumenDtaattai:o:nObjectDriver::SQL(3pm)
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6 Data::ObjectDriver::SQL - an SQL statement
7
9 my $sql = Data::ObjectDriver::SQL->new();
10 $sql->select([ 'id', 'name', 'bucket_id', 'note_id' ]);
11 $sql->from([ 'foo' ]);
12 $sql->add_where('name', 'fred');
13 $sql->add_where('bucket_id', { op => '!=', value => 47 });
14 $sql->add_where('note_id', \'IS NULL');
15 $sql->limit(1);
16 my $sth = $dbh->prepare($sql->as_sql);
18 $sth->execute(@{ $sql->{bind} });
19 my @values = $sth->selectrow_array();
20 my $obj = SomeObject->new();
22 $obj->set_columns(...);
23
25 Data::ObjectDriver::SQL represents an SQL statement. SQL statements are
26 used internally to "Data::ObjectDriver::Driver::DBI" object drivers to
27 convert database operations ("search()", "update()", etc) into database
28 operations, but sometimes you just gotta use SQL.
29
31 Data::ObjectDriver::SQL sports several data attributes that represent
32 the parts of the modeled SQL statement. These attributes all have
33 accessor and mutator methods. Note that some attributes have more
34 convenient methods of modification (for example, "add_where()" for the
35 "where" attribute).
36 "select" (arrayref)
38 The database columns to select in a "SELECT" query.
39 "distinct" (boolean)
41 Whether the "SELECT" query should return DISTINCT rows only.
42 "select_map" (hashref)
44 The map of database column names to object fields in a "SELECT" query.
45 Use this mapping to convert members of the "select" list to column
46 names.
47 "select_map_reverse" (hashref)
49 The map of object fields to database column names in a "SELECT" query.
50 Use this map to reverse the "select_map" mapping where needed.
51 "from" (arrayref)
53 The list of tables from which to query results in a "SELECT" query.
54 Note if you perform a "SELECT" query with multiple tables, the rows
56 will be selected as Cartesian products that you'll need to reduce with
57 "WHERE" clauses. Your query might be better served with real joins
58 specified through the "joins" attribute of your statement.
59 "joins" (arrayref of hashrefs containing scalars and hashrefs)
61 The list of "JOIN" clauses to use in the table list of the statement.
62 Each clause is a hashref containing these members:
63 · "table"
65 The name of the table in "from" being joined.
67 · "joins" (arrayref)
69 The list of joins to perform on the table named in "table". Each
71 member of "joins" is a hashref containing:
72 · "type"
74 The type of join to use. That is, the SQL string to use before
76 the word "JOIN" in the join expression; for example, "INNER" or
77 "NATURAL RIGHT OUTER"). This member is optional. When not
78 specified, the default plain "JOIN" join is specified.
79 · "table"
81 The name of the table to which to join.
83 · "condition"
85 The SQL expression across which to perform the join, as a
87 string.
88 "where" (arrayref)
90 The list of "WHERE" clauses that apply to the SQL statement. Individual
91 members of the list are strings of SQL. All members of this attribute
92 must be true for a record to be included as a result; that is, the list
93 members are "AND"ed together to form the full "WHERE" clause.
94 "where_values" (hashref of variant structures)
96 The set of data structures used to generate the "WHERE" clause SQL
97 found in the "where" attributes, keyed on the associated column names.
98 "bind" (arrayref)
100 The list of values to bind to the query when performed. That is, the
101 list of values to be replaced for the "?"es in the SQL.
102 "limit" (scalar)
104 The maximum number of results on which to perform the query.
105 "offset" (scalar)
107 The number of records to skip before performing the query. Combined
108 with a "limit" and application logic to increase the offset in
109 subsequent queries, you can paginate a set of records with a moving
110 window containing "limit" records.
111 "group" (hashref, or an arrayref of hashrefs)
113 The fields on which to group the results. Grouping fields are hashrefs
114 containing these members:
115 · "column"
117 Name of the column on which to group.
119 Note you can set a single grouping field, or use an arrayref containing
121 multiple grouping fields.
122 "having" (arrayref)
124 The list of clauses to specify in the "HAVING" portion of a "GROUP ...
125 HAVING" clause. Individual clauses are simple strings containing the
126 conditional expression, as in "where".
127 "order" (hashref, or an arrayref of hashrefs)
129 Returns or sets the fields by which to order the results. Ordering
130 fields are hashrefs containing these members:
131 · "column"
133 Name of the column by which to order.
135 · "desc"
137 The SQL keyword to use to specify the ordering. For example, use
139 "DESC" to specify a descending order. This member is optional.
140 Note you can set a single ordering field, or use an arrayref containing
142 multiple ordering fields.
143 "$sql->comment([ $comment ])"
145 Returns or sets a simple comment to the SQL statement
146
148 "Data::ObjectDriver::SQL->new()"
149 Creates a new, empty SQL statement.
150 "$sql->add_select($column [, $term ])"
152 Adds the database column $column to the list of fields to return in a
153 "SELECT" query. The requested object member will be indicated to be
154 $term in the statement's "select_map" and "select_map_reverse"
155 attributes.
156 $term is optional, and defaults to the same value as $column.
158 "$sql->add_join($table, \@joins)"
160 Adds the join statement indicated by $table and "\@joins" to the list
161 of "JOIN" table references for the statement. The structure for the set
162 of joins are as described for the "joins" attribute member above.
163 "$sql->add_index_hint($table, $index)"
165 Specifies a particular index to use for a particular table.
166 "$sql->add_where($column, $value)"
168 Adds a condition on the value of the database column $column to the
169 statement's "WHERE" clause. A record will be tested against the below
170 conditions according to what type of data structure $value is:
171 · a scalar
173 The value of $column must equal $value.
175 · a reference to a scalar
177 The value of $column must evaluate true against the SQL given in
179 $$value. For example, if $$value were "IS NULL", $column must be
180 "NULL" for a record to pass.
181 · a hashref
183 The value of $column must compare against the condition represented
185 by $value, which can contain the members:
186 · "value"
188 The value with which to compare (required).
190 · "op"
192 The SQL operator with which to compare "value" and the value of
194 $column (required).
195 · "column"
197 The column name for the comparison. If this is present, it
199 overrides the column name $column, allowing you to build more
200 complex conditions like "((foo = 1 AND bar = 2) OR (baz = 3))".
201 For example, if "value" were "NULL" and "op" were "IS", a record's
203 $column column would have to be "NULL" to match.
204 · an arrayref of scalars
206 The value of $column may equal any of the members of @$value. The
208 generated SQL performs the comparison with as an "IN" expression.
209 · an arrayref of (mostly) references
211 The value of $column must compare against any of the expressions
213 represented in @$value. Each member of the list can be any of the
214 structures described here as possible forms of $value.
215 If the first member of the @$value array is the scalar string
217 "-and", all subsequent members of <@$value> must be met for the
218 record to match. Note this is not very useful unless contained as
219 one option of a larger "OR" alternation.
220 All individual conditions specified with "add_where()" must be true for
222 a record to be a result of the query.
223 Beware that you can create a circular reference that will recursively
225 generate an infinite SQL statement (for example, by specifying a
226 arrayref $value that itself contains $value). As "add_where()"
227 evaluates your expressions before storing the conditions in the "where"
228 attribute as a generated SQL string, this will occur when calling
229 "add_where()", not "as_sql()". So don't do that.
230 "$sql->add_complex_where(\@list)"
232 This method accepts an array reference of clauses that are glued
233 together with logical operators. With it, you can express where clauses
234 that mix logical operators together to produce more complex queries.
235 For instance:
236 [ { foo => 1, bar => 2 }, -or => { baz => 3 } ]
238 The values given for the columns support all the variants documented
240 for the "add_where()" method above. Logical operators used inbetween
241 the hashref elements can be one of: '-or', '-and', '-or_not',
242 '-and_not'.
243 "$sql->has_where($column, [$value])"
245 Returns whether a where clause for the column $column was added to the
246 statement with the "add_where()" method.
247 The $value argument is currently ignored.
249 "$sql->add_having($column, $value)"
251 Adds an expression to the "HAVING" portion of the statement's "GROUP
252 ... HAVING" clause. The expression compares $column using $value,
253 which can be any of the structures described above for the
254 "add_where()" method.
255 "$sql->add_index_hint($table, \@hints)"
257 Addes the index hint into a "SELECT" query. The structure for the set
258 of "\@hints" are arrayref of hashrefs containing these members:
259 · "type" (scalar)
261 The name of the type. "USE", "IGNORE or "FORCE".
263 · "list" (arrayref)
265 The list of name of indexes which to use.
267 "$sql->as_sql()"
269 Returns the SQL fully representing the SQL statement $sql.
270 "$sql->as_sql_having()"
272 Returns the SQL representing the "HAVING" portion of $sql's "GROUP ...
273 HAVING" clause.
274 "$sql->as_sql_where()"
276 Returns the SQL representing $sql's "WHERE" clause.
277 "$sql->as_limit()"
279 Returns the SQL for the "LIMIT ... OFFSET" clause of the statement.
280 "$sql->as_aggregate($set)"
282 Returns the SQL representing the aggregation clause of type $set for
283 the SQL statement $sql. Reasonable values of $set are "ORDER" and
284 "GROUP".
285
287 · "Invalid/unsafe column name column"
288 The column name you specified to "add_where()" contained characters
290 that are not allowed in database column names. Only word characters
291 and periods are allowed. Perhaps you didn't filter punctuation out
292 of a generated column name correctly.
293
295 Data::ObjectDriver::SQL does not provide the functionality for turning
296 SQL statements into instances of object classes.
297
300 Data::ObjectDriver is free software; you may redistribute it and/or
301 modify it under the same terms as Perl itself.
302
304 Except where otherwise noted, Data::ObjectDriver is Copyright 2005-2006
305 Six Apart, cpan@sixapart.com. All rights reserved.
306perl v5.30.0 2019-07-26 Data::ObjectDriver::SQL(3pm)