Module: Sequel::SQLite::DatasetMethods

Included in:
Amalgalite::Dataset, DataObjects::SQLite::Dataset, JDBC::SQLite::Dataset, Dataset
Defined in:
lib/sequel/adapters/shared/sqlite.rb

Overview

Instance methods for datasets that connect to an SQLite database

Constant Summary collapse

SELECT_CLAUSE_METHODS = 
Dataset.clause_methods(:select, %w'distinct columns from join where group having compounds order limit')
CONSTANT_MAP = 
{:CURRENT_DATE=>"date(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIMESTAMP=>"datetime(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIME=>"time(CURRENT_TIMESTAMP, 'localtime')".freeze}

Instance Method Summary collapse

Instance Method Details

#complex_expression_sql(op, args) ⇒ Object

SQLite does not support pattern matching via regular expressions. SQLite is case insensitive (depending on pragma), so use LIKE for ILIKE.



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# File 'lib/sequel/adapters/shared/sqlite.rb', line 244

def complex_expression_sql(op, args)
  case op
  when :~, :'!~', :'~*', :'!~*'
    raise Error, "SQLite does not support pattern matching via regular expressions"
  when :LIKE, :'NOT LIKE', :ILIKE, :'NOT ILIKE'
    # SQLite is case insensitive for ASCII, and non case sensitive for other character sets
    "#{'NOT ' if [:'NOT LIKE', :'NOT ILIKE'].include?(op)}(#{literal(args.at(0))} LIKE #{literal(args.at(1))})"
  else
    super(op, args)
  end
end

#constant_sql(constant) ⇒ Object

MSSQL doesn’t support the SQL standard CURRENT_DATE or CURRENT_TIME



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# File 'lib/sequel/adapters/shared/sqlite.rb', line 257

def constant_sql(constant)
  CONSTANT_MAP[constant] || super
end

#delete ⇒ Object

SQLite performs a TRUNCATE style DELETE if no filter is specified. Since we want to always return the count of records, add a condition that is always true and then delete.



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# File 'lib/sequel/adapters/shared/sqlite.rb', line 264

def delete
  @opts[:where] ? super : filter(1=>1).delete
end

#explain ⇒ Object

Return an array of strings specifying a query explanation for a SELECT of the current dataset.



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# File 'lib/sequel/adapters/shared/sqlite.rb', line 270

def explain
  db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}").
    map{|x| "#{x[:addr]}|#{x[:opcode]}|#{(1..5).map{|i| x[:"p#{i}"]}.join('|')}|#{x[:comment]}"}
end

#having(*cond, &block) ⇒ Object

HAVING requires GROUP BY on SQLite

Raises:



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# File 'lib/sequel/adapters/shared/sqlite.rb', line 276

def having(*cond, &block)
  raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group]
  super
end

#quoted_identifier(c) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/sqlite.rb', line 282

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

#supports_intersect_except_all? ⇒ Boolean

SQLite does not support INTERSECT ALL or EXCEPT ALL

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/sqlite.rb', line 287

def supports_intersect_except_all?
  false
end

#supports_is_true? ⇒ Boolean

SQLite does not support IS TRUE

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/sqlite.rb', line 292

def supports_is_true?
  false
end

#supports_multiple_column_in? ⇒ Boolean

SQLite does not support multiple columns for the IN/NOT IN operators

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/sqlite.rb', line 297

def supports_multiple_column_in?
  false
end

#supports_timestamp_timezones? ⇒ Boolean

SQLite supports timezones in literal timestamps, since it stores them as text.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/sqlite.rb', line 303

def supports_timestamp_timezones?
  true
end