Module: Sequel::MySQL::DatasetMethods

Included in:
DataObjects::MySQL::Dataset, JDBC::MySQL::Dataset, Dataset
Defined in:
lib/sequel/adapters/shared/mysql.rb

Overview

Dataset methods shared by datasets that use MySQL databases.

Constant Summary collapse

BOOL_TRUE = 
'1'.freeze
BOOL_FALSE = 
'0'.freeze
COMMA_SEPARATOR = 
', '.freeze
FOR_SHARE = 
' LOCK IN SHARE MODE'.freeze
DELETE_CLAUSE_METHODS = 
Dataset.clause_methods(:delete, %w'from where order limit')
INSERT_CLAUSE_METHODS = 
Dataset.clause_methods(:insert, %w'ignore into columns values on_duplicate_key_update')
SELECT_CLAUSE_METHODS = 
Dataset.clause_methods(:select, %w'distinct columns from join where group having compounds order limit lock')
UPDATE_CLAUSE_METHODS = 
Dataset.clause_methods(:update, %w'table set where order limit')

Instance Method Summary collapse

Instance Method Details

#complex_expression_sql(op, args) ⇒ Object

MySQL specific syntax for LIKE/REGEXP searches, as well as string concatenation.



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# File 'lib/sequel/adapters/shared/mysql.rb', line 294

def complex_expression_sql(op, args)
  case op
  when :~, :'!~', :'~*', :'!~*', :LIKE, :'NOT LIKE', :ILIKE, :'NOT ILIKE'
    "(#{literal(args.at(0))} #{'NOT ' if [:'NOT LIKE', :'NOT ILIKE', :'!~', :'!~*'].include?(op)}#{[:~, :'!~', :'~*', :'!~*'].include?(op) ? 'REGEXP' : 'LIKE'} #{'BINARY ' if [:~, :'!~', :LIKE, :'NOT LIKE'].include?(op)}#{literal(args.at(1))})"
  when :'||'
    if args.length > 1
      "CONCAT(#{args.collect{|a| literal(a)}.join(', ')})"
    else
      literal(args.at(0))
    end
  when :'B~'
    "CAST(~#{literal(args.at(0))} AS SIGNED INTEGER)"
  else
    super(op, args)
  end
end

#distinct(*args) ⇒ Object

Use GROUP BY instead of DISTINCT ON if arguments are provided.



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# File 'lib/sequel/adapters/shared/mysql.rb', line 312

def distinct(*args)
  args.empty? ? super : group(*args)
end

#for_share ⇒ Object

Return a cloned dataset which will use LOCK IN SHARE MODE to lock returned rows.



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# File 'lib/sequel/adapters/shared/mysql.rb', line 317

def for_share
  lock_style(:share)
end

#full_text_search(cols, terms, opts = {}) ⇒ Object

Adds full text filter



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# File 'lib/sequel/adapters/shared/mysql.rb', line 322

def full_text_search(cols, terms, opts = {})
  filter(full_text_sql(cols, terms, opts))
end

#full_text_sql(cols, term, opts = {}) ⇒ Object

MySQL specific full text search syntax.



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# File 'lib/sequel/adapters/shared/mysql.rb', line 327

def full_text_sql(cols, term, opts = {})
  "MATCH #{literal(Array(cols))} AGAINST (#{literal(Array(term).join(' '))}#{" IN BOOLEAN MODE" if opts[:boolean]})"
end

#having(*cond, &block) ⇒ Object

MySQL allows HAVING clause on ungrouped datasets.



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# File 'lib/sequel/adapters/shared/mysql.rb', line 332

def having(*cond, &block)
  _filter(:having, *cond, &block)
end

#insert_ignore ⇒ Object

Sets up the insert methods to use INSERT IGNORE. Useful if you have a unique key and want to just skip inserting rows that violate the unique key restriction.

dataset.insert_ignore.multi_insert(
 [{:name => 'a', :value => 1}, {:name => 'b', :value => 2}]
)
# INSERT IGNORE INTO tablename (name, value) VALUES (a, 1), (b, 2)



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# File 'lib/sequel/adapters/shared/mysql.rb', line 362

def insert_ignore
  clone(:insert_ignore=>true)
end

#join_table(type, table, expr = nil, table_alias = {}) ⇒ Object

Transforms an CROSS JOIN to an INNER JOIN if the expr is not nil. Raises an error on use of :full_outer type, since MySQL doesn’t support it.

Raises:



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# File 'lib/sequel/adapters/shared/mysql.rb', line 338

def join_table(type, table, expr=nil, table_alias={})
  type = :inner if (type == :cross) && !expr.nil?
  raise(Sequel::Error, "MySQL doesn't support FULL OUTER JOIN") if type == :full_outer
  super(type, table, expr, table_alias)
end

#join_type_sql(join_type) ⇒ Object

Transforms :natural_inner to NATURAL LEFT JOIN and straight to STRAIGHT_JOIN.



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# File 'lib/sequel/adapters/shared/mysql.rb', line 346

def join_type_sql(join_type)
  case join_type
  when :straight then 'STRAIGHT_JOIN'
  when :natural_inner then 'NATURAL LEFT JOIN'
  else super
  end
end

#multi_insert_sql(columns, values) ⇒ Object

MySQL specific syntax for inserting multiple values at once.



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# File 'lib/sequel/adapters/shared/mysql.rb', line 390

def multi_insert_sql(columns, values)
  [insert_sql(columns, LiteralString.new('VALUES ' + values.map {|r| literal(Array(r))}.join(COMMA_SEPARATOR)))]
end

#on_duplicate_key_update(*args) ⇒ Object

Sets up the insert methods to use ON DUPLICATE KEY UPDATE If you pass no arguments, ALL fields will be updated with the new values. If you pass the fields you want then ONLY those field will be updated.

Useful if you have a unique key and want to update inserting rows that violate the unique key restriction.

dataset.on_duplicate_key_update.multi_insert(
 [{:name => 'a', :value => 1}, {:name => 'b', :value => 2}]
)
# INSERT INTO tablename (name, value) VALUES (a, 1), (b, 2)
# ON DUPLICATE KEY UPDATE name=VALUES(name), value=VALUES(value)

dataset.on_duplicate_key_update(:value).multi_insert(
  [{:name => 'a', :value => 1}, {:name => 'b', :value => 2}]
)
# INSERT INTO tablename (name, value) VALUES (a, 1), (b, 2)
# ON DUPLICATE KEY UPDATE value=VALUES(value)



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# File 'lib/sequel/adapters/shared/mysql.rb', line 385

def on_duplicate_key_update(*args)
  clone(:on_duplicate_key_update => args)
end

#provides_accurate_rows_matched? ⇒ Boolean

MySQL uses the number of rows actually modified in the update, instead of the number of matched by the filter.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/mysql.rb', line 396

def provides_accurate_rows_matched?
  false
end

#quoted_identifier(c) ⇒ Object

MySQL uses the nonstandard ‘ (backtick) for quoting identifiers.



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# File 'lib/sequel/adapters/shared/mysql.rb', line 401

def quoted_identifier(c)
  "`#{c}`"
end

#replace_sql(*values) ⇒ Object

MySQL specific syntax for REPLACE (aka UPSERT, or update if exists, insert if it doesn’t).



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# File 'lib/sequel/adapters/shared/mysql.rb', line 407

def replace_sql(*values)
  clone(:replace=>true).insert_sql(*values)
end

#supports_distinct_on? ⇒ Boolean

MySQL can emulate DISTINCT ON with its non-standard GROUP BY implementation, though the rows returned cannot be made deterministic through ordering.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/mysql.rb', line 413

def supports_distinct_on?
  true
end

#supports_intersect_except? ⇒ Boolean

MySQL does not support INTERSECT or EXCEPT

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/mysql.rb', line 418

def supports_intersect_except?
  false
end

#supports_modifying_joins? ⇒ Boolean

MySQL supports modifying joined datasets

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/mysql.rb', line 423

def supports_modifying_joins?
  true
end

#supports_timestamp_usecs? ⇒ Boolean

MySQL does support fractional timestamps in literal timestamps, but it ignores them. Also, using them seems to cause problems on 1.9. Since they are ignored anyway, not using them is probably best.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/mysql.rb', line 430

def supports_timestamp_usecs?
  false
end