Module: Sequel::MySQL::DatasetMethods

Includes:
Dataset::Replace, UnmodifiedIdentifiers::DatasetMethods
Included in:
Dataset, Sequel::Mysql2::Dataset
Defined in:
lib/sequel/adapters/shared/mysql.rb

Overview

Dataset methods shared by datasets that use MySQL databases.

Constant Summary collapse

MATCH_AGAINST = 
["MATCH ".freeze, " AGAINST (".freeze, ")".freeze].freeze
MATCH_AGAINST_BOOLEAN = 
["MATCH ".freeze, " AGAINST (".freeze, " IN BOOLEAN MODE)".freeze].freeze

Instance Method Summary collapse

Methods included from Dataset::Replace

#multi_replace, #replace, #replace_sql, #supports_replace?

Instance Method Details

#calc_found_rows ⇒ Object

Sets up the select methods to use SQL_CALC_FOUND_ROWS option.

dataset.calc_found_rows.limit(10)
# SELECT SQL_CALC_FOUND_ROWS * FROM table LIMIT 10


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# File 'lib/sequel/adapters/shared/mysql.rb', line 614

def calc_found_rows
  clone(:calc_found_rows => true)
end

#complex_expression_sql_append(sql, op, args) ⇒ Object 


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# File 'lib/sequel/adapters/shared/mysql.rb', line 554

def complex_expression_sql_append(sql, op, args)
  case op
  when :IN, :"NOT IN"
    ds = args[1]
    if ds.is_a?(Sequel::Dataset) && ds.opts[:limit]
      super(sql, op, [args[0], ds.from_self])
    else
      super
    end
  when :~, :'!~', :'~*', :'!~*', :LIKE, :'NOT LIKE', :ILIKE, :'NOT ILIKE'
    sql << '('
    literal_append(sql, args[0])
    sql << ' '
    sql << 'NOT ' if [:'NOT LIKE', :'NOT ILIKE', :'!~', :'!~*'].include?(op)
    sql << ([:~, :'!~', :'~*', :'!~*'].include?(op) ? 'REGEXP' : 'LIKE')
    sql << ' '
    sql << 'BINARY ' if [:~, :'!~', :LIKE, :'NOT LIKE'].include?(op)
    literal_append(sql, args[1])
    if [:LIKE, :'NOT LIKE', :ILIKE, :'NOT ILIKE'].include?(op)
      sql << " ESCAPE "
      literal_append(sql, "\\")
    end
    sql << ')'
  when :'||'
    if args.length > 1
      sql << "CONCAT"
      array_sql_append(sql, args)
    else
      literal_append(sql, args[0])
    end
  when :'B~'
    sql << "CAST(~"
    literal_append(sql, args[0])
    sql << " AS SIGNED INTEGER)"
  else
    super
  end
end

#constant_sql_append(sql, constant) ⇒ Object

MySQL's CURRENT_TIMESTAMP does not use fractional seconds, even if the database itself supports fractional seconds. If MySQL 5.6.4+ is being used, use a value that will return fractional seconds.


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# File 'lib/sequel/adapters/shared/mysql.rb', line 597

def constant_sql_append(sql, constant)
  if constant == :CURRENT_TIMESTAMP && supports_timestamp_usecs?
    sql << 'CURRENT_TIMESTAMP(6)'
  else
    super
  end
end

#delete_from(*tables) ⇒ Object

Sets up the select methods to delete from if deleting from a joined dataset:

DB[:a].join(:b, a_id: :id).delete
# DELETE a FROM a INNER JOIN b ON (b.a_id = a.id)

DB[:a].join(:b, a_id: :id).delete_from(:a, :b).delete
# DELETE a, b FROM a INNER JOIN b ON (b.a_id = a.id)


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# File 'lib/sequel/adapters/shared/mysql.rb', line 626

def delete_from(*tables)
  clone(:delete_from=>tables)
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 606

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

#explain(opts = OPTS) ⇒ Object

Return the results of an EXPLAIN query as a string. Options:

:extended

Use EXPLAIN EXPTENDED instead of EXPLAIN if true.


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# File 'lib/sequel/adapters/shared/mysql.rb', line 632

def explain(opts=OPTS)
  # Load the PrettyTable class, needed for explain output
  Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable)

  ds = db.send(:metadata_dataset).with_sql((opts[:extended] ? 'EXPLAIN EXTENDED ' : 'EXPLAIN ') + select_sql).naked
  rows = ds.all
  Sequel::PrettyTable.string(rows, ds.columns)
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 642

def for_share
  lock_style(:share)
end

#full_text_search(cols, terms, opts = OPTS) ⇒ Object

Adds full text filter


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# File 'lib/sequel/adapters/shared/mysql.rb', line 647

def full_text_search(cols, terms, opts = OPTS)
  where(full_text_sql(cols, terms, opts))
end

#full_text_sql(cols, terms, opts = OPTS) ⇒ Object

MySQL specific full text search syntax.


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# File 'lib/sequel/adapters/shared/mysql.rb', line 652

def full_text_sql(cols, terms, opts = OPTS)
  terms = terms.join(' ') if terms.is_a?(Array)
  SQL::PlaceholderLiteralString.new((opts[:boolean] ? MATCH_AGAINST_BOOLEAN : MATCH_AGAINST), [Array(cols), terms])
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 674

def insert_ignore
  clone(:insert_ignore=>true)
end

#join_type_sql(join_type) ⇒ Object

Transforms :straight to STRAIGHT_JOIN.


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# File 'lib/sequel/adapters/shared/mysql.rb', line 658

def join_type_sql(join_type)
  if join_type == :straight
    'STRAIGHT_JOIN'
  else
    super
  end
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. If you pass a hash you can customize the values (for example, to increment a numeric field).

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)

dataset.on_duplicate_key_update(
  value: Sequel.lit('value + VALUES(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=value + VALUES(value)


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# File 'lib/sequel/adapters/shared/mysql.rb', line 707

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

#quoted_identifier_append(sql, c) ⇒ Object

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


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# File 'lib/sequel/adapters/shared/mysql.rb', line 712

def quoted_identifier_append(sql, c)
  sql << '`' << c.to_s.gsub('`', '``') << '`'
end

#supports_derived_column_lists? ⇒ Boolean

MySQL does not support derived column lists


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# File 'lib/sequel/adapters/shared/mysql.rb', line 717

def supports_derived_column_lists?
  false
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.


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# File 'lib/sequel/adapters/shared/mysql.rb', line 723

def supports_distinct_on?
  true
end

#supports_group_rollup? ⇒ Boolean

MySQL supports GROUP BY WITH ROLLUP (but not CUBE)


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# File 'lib/sequel/adapters/shared/mysql.rb', line 728

def supports_group_rollup?
  true
end

#supports_intersect_except? ⇒ Boolean

MySQL does not support INTERSECT or EXCEPT


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# File 'lib/sequel/adapters/shared/mysql.rb', line 733

def supports_intersect_except?
  false
end

#supports_limits_in_correlated_subqueries? ⇒ Boolean

MySQL does not support limits in correlated subqueries (or any subqueries that use IN).


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# File 'lib/sequel/adapters/shared/mysql.rb', line 738

def supports_limits_in_correlated_subqueries?
  false
end

#supports_modifying_joins? ⇒ Boolean

MySQL supports modifying joined datasets


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# File 'lib/sequel/adapters/shared/mysql.rb', line 743

def supports_modifying_joins?
  true
end

#supports_ordered_distinct_on? ⇒ Boolean

MySQL's DISTINCT ON emulation using GROUP BY does not respect the query's ORDER BY clause.


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# File 'lib/sequel/adapters/shared/mysql.rb', line 749

def supports_ordered_distinct_on?
  false
end

#supports_regexp? ⇒ Boolean

MySQL supports pattern matching via regular expressions


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# File 'lib/sequel/adapters/shared/mysql.rb', line 754

def supports_regexp?
  true
end

#supports_timestamp_usecs? ⇒ Boolean

Check the database setting for whether fractional timestamps are suppported.


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# File 'lib/sequel/adapters/shared/mysql.rb', line 760

def supports_timestamp_usecs?
  db.supports_timestamp_usecs?
end

#update_ignore ⇒ Object

Sets up the update methods to use UPDATE IGNORE. Useful if you have a unique key and want to just skip updating rows that violate the unique key restriction.

dataset.update_ignore.update(name: 'a', value: 1)
# UPDATE IGNORE tablename SET name = 'a', value = 1


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# File 'lib/sequel/adapters/shared/mysql.rb', line 770

def update_ignore
  clone(:update_ignore=>true)
end