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_rowsObject

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 677

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 611

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'
    if !db.mariadb? && db.server_version >= 80000 && [:~, :'!~'].include?(op)
      func = Sequel.function(:REGEXP_LIKE, args[0], args[1], 'c')
      func = ~func if op == :'!~'
      return literal_append(sql, func)
    end

    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 660

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 689

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 669

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 EXTENDED instead of EXPLAIN if true.


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# File 'lib/sequel/adapters/shared/mysql.rb', line 695

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] && (db.mariadb? || db.server_version < 50700)) ? 'EXPLAIN EXTENDED ' : 'EXPLAIN ') + select_sql).naked
  rows = ds.all
  Sequel::PrettyTable.string(rows, ds.columns)
end

#for_shareObject

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 705

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 710

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 715

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_ignoreObject

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 728

def insert_ignore
  clone(:insert_ignore=>true)
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 761

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 766

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

#supports_cte?(type = :select) ⇒ Boolean

MariaDB 10.2+ and MySQL 8+ support CTEs

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 771

def supports_cte?(type=:select)
  if db.mariadb?
    type == :select && db.server_version >= 100200
  else
    case type
    when :select, :update, :delete
      db.server_version >= 80000
    end
  end
end

#supports_derived_column_lists?Boolean

MySQL does not support derived column lists

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 783

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.

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 789

def supports_distinct_on?
  true
end

#supports_group_rollup?Boolean

MySQL supports GROUP BY WITH ROLLUP (but not CUBE)

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 794

def supports_group_rollup?
  true
end

#supports_intersect_except?Boolean

MariaDB 10.3+ supports INTERSECT or EXCEPT

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 799

def supports_intersect_except?
  db.mariadb? && db.server_version >= 100300
end

#supports_limits_in_correlated_subqueries?Boolean

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

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 804

def supports_limits_in_correlated_subqueries?
  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 809

def supports_modifying_joins?
  true
end

#supports_nowait?Boolean

MySQL 8+ and MariaDB 10.3+ support NOWAIT.

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 814

def supports_nowait?
  db.server_version >= (db.mariadb? ? 100300 : 80000)
end

#supports_ordered_distinct_on?Boolean

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

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 820

def supports_ordered_distinct_on?
  false
end

#supports_regexp?Boolean

MySQL supports pattern matching via regular expressions

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 825

def supports_regexp?
  true
end

#supports_skip_locked?Boolean

MySQL 8+ supports SKIP LOCKED.

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 830

def supports_skip_locked?
  !db.mariadb? && db.server_version >= 80000
end

#supports_timestamp_usecs?Boolean

Check the database setting for whether fractional timestamps are suppported.

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 836

def supports_timestamp_usecs?
  db.supports_timestamp_usecs?
end

#supports_window_clause?Boolean

MySQL 8+ supports WINDOW clause.

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 841

def supports_window_clause?
  !db.mariadb? && db.server_version >= 80000
end

#supports_window_functions?Boolean

MariaDB 10.2+ and MySQL 8+ support window functions

Returns:

  • (Boolean)

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# File 'lib/sequel/adapters/shared/mysql.rb', line 846

def supports_window_functions?
  db.server_version >= (db.mariadb? ? 100200 : 80000)
end

#update_ignoreObject

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 856

def update_ignore
  clone(:update_ignore=>true)
end