1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
module ActiveRecord
module ConnectionAdapters # :nodoc:
module DatabaseStatements
# Returns an array of record hashes with the column names as keys and
# column values as values.
def select_all(sql, name = nil)
select(sql, name)
end
# Returns a record hash with the column names as keys and column values
# as values.
def select_one(sql, name = nil)
result = select_all(sql, name)
result.first if result
end
# Returns a single value from a record
def select_value(sql, name = nil)
if result = select_one(sql, name)
result.values.first
end
end
# Returns an array of the values of the first column in a select:
# select_values("SELECT id FROM companies LIMIT 3") => [1,2,3]
def select_values(sql, name = nil)
result = select_rows(sql, name)
result.map { |v| v[0] }
end
# Returns an array of arrays containing the field values.
# Order is the same as that returned by #columns.
def select_rows(sql, name = nil)
raise NotImplementedError, "select_rows is an abstract method"
end
# Executes the SQL statement in the context of this connection.
def execute(sql, name = nil)
raise NotImplementedError, "execute is an abstract method"
end
# Returns the last auto-generated ID from the affected table.
def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
insert_sql(sql, name, pk, id_value, sequence_name)
end
# Executes the update statement and returns the number of rows affected.
def update(sql, name = nil)
update_sql(sql, name)
end
# Executes the delete statement and returns the number of rows affected.
def delete(sql, name = nil)
delete_sql(sql, name)
end
# Wrap a block in a transaction. Returns result of block.
def transaction(start_db_transaction = true)
transaction_open = false
begin
if block_given?
if start_db_transaction
begin_db_transaction
transaction_open = true
end
yield
end
rescue Exception => database_transaction_rollback
if transaction_open
transaction_open = false
rollback_db_transaction
end
raise unless database_transaction_rollback.is_a? ActiveRecord::Rollback
end
ensure
if transaction_open
begin
commit_db_transaction
rescue Exception => database_transaction_rollback
rollback_db_transaction
raise
end
end
end
# Begins the transaction (and turns off auto-committing).
def begin_db_transaction() end
# Commits the transaction (and turns on auto-committing).
def commit_db_transaction() end
# Rolls back the transaction (and turns on auto-committing). Must be
# done if the transaction block raises an exception or returns false.
def rollback_db_transaction() end
# Alias for #add_limit_offset!.
def add_limit!(sql, options)
add_limit_offset!(sql, options) if options
end
# Appends +LIMIT+ and +OFFSET+ options to an SQL statement.
# This method *modifies* the +sql+ parameter.
# ===== Examples
# add_limit_offset!('SELECT * FROM suppliers', {:limit => 10, :offset => 50})
# generates
# SELECT * FROM suppliers LIMIT 10 OFFSET 50
def add_limit_offset!(sql, options)
if limit = options[:limit]
sql << " LIMIT #{limit}"
if offset = options[:offset]
sql << " OFFSET #{offset}"
end
end
end
# Appends a locking clause to an SQL statement.
# This method *modifies* the +sql+ parameter.
# # SELECT * FROM suppliers FOR UPDATE
# add_lock! 'SELECT * FROM suppliers', :lock => true
# add_lock! 'SELECT * FROM suppliers', :lock => ' FOR UPDATE'
def add_lock!(sql, options)
case lock = options[:lock]
when true; sql << ' FOR UPDATE'
when String; sql << " #{lock}"
end
end
def default_sequence_name(table, column)
nil
end
# Set the sequence to the max value of the table's column.
def reset_sequence!(table, column, sequence = nil)
# Do nothing by default. Implement for PostgreSQL, Oracle, ...
end
# Inserts the given fixture into the table. Overridden in adapters that require
# something beyond a simple insert (eg. Oracle).
def insert_fixture(fixture, table_name)
execute "INSERT INTO #{quote_table_name(table_name)} (#{fixture.key_list}) VALUES (#{fixture.value_list})", 'Fixture Insert'
end
def empty_insert_statement(table_name)
"INSERT INTO #{quote_table_name(table_name)} VALUES(DEFAULT)"
end
protected
# Returns an array of record hashes with the column names as keys and
# column values as values.
def select(sql, name = nil)
raise NotImplementedError, "select is an abstract method"
end
# Returns the last auto-generated ID from the affected table.
def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
execute(sql, name)
id_value
end
# Executes the update statement and returns the number of rows affected.
def update_sql(sql, name = nil)
execute(sql, name)
end
# Executes the delete statement and returns the number of rows affected.
def delete_sql(sql, name = nil)
update_sql(sql, name)
end
end
end
end
|
