Module: Sequel::Access::DatasetMethods

Includes:
EmulateOffsetWithReverseAndCount, UnmodifiedIdentifiers::DatasetMethods
Included in:
Sequel::ADO::Access::Dataset
Defined in:
lib/sequel/adapters/shared/access.rb

Constant Summary collapse

DATE_FORMAT = 
'#%Y-%m-%d#'.freeze
TIMESTAMP_FORMAT = 
'#%Y-%m-%d %H:%M:%S#'.freeze
TOP = 
" TOP ".freeze
BRACKET_CLOSE = 
Dataset::BRACKET_CLOSE
BRACKET_OPEN = 
Dataset::BRACKET_OPEN
PAREN_CLOSE = 
Dataset::PAREN_CLOSE
PAREN_OPEN = 
Dataset::PAREN_OPEN
INTO = 
Dataset::INTO
FROM = 
Dataset::FROM
SPACE = 
Dataset::SPACE
NOT_EQUAL = 
' <> '.freeze
OPS = 
{:'%'=>' Mod '.freeze, :'||'=>' & '.freeze}
BOOL_FALSE = 
'0'.freeze
BOOL_TRUE = 
'-1'.freeze
DATE_FUNCTION = 
'Date()'.freeze
NOW_FUNCTION = 
'Now()'.freeze
TIME_FUNCTION = 
'Time()'.freeze
CAST_TYPES = 
{String=>:CStr, Integer=>:CLng, Date=>:CDate, Time=>:CDate, DateTime=>:CDate, Numeric=>:CDec, BigDecimal=>:CDec, File=>:CStr, Float=>:CDbl, TrueClass=>:CBool, FalseClass=>:CBool}
EMULATED_FUNCTION_MAP = 
{:char_length=>:len}
EXTRACT_MAP = 
{:year=>"'yyyy'", :month=>"'m'", :day=>"'d'", :hour=>"'h'", :minute=>"'n'", :second=>"'s'"}
COMMA = 
Dataset::COMMA
DATEPART_OPEN = 
"datepart(".freeze

Instance Method Summary collapse

Methods included from EmulateOffsetWithReverseAndCount

#empty?, #select_sql, #supports_offsets_in_correlated_subqueries?

Instance Method Details

#case_expression_sql_append(sql, ce) ⇒ Object

Access doesn’t support CASE, but it can be emulated with nested IIF function calls.



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# File 'lib/sequel/adapters/shared/access.rb', line 114

def case_expression_sql_append(sql, ce)
  literal_append(sql, ce.with_merged_expression.conditions.reverse.inject(ce.default){|exp,(cond,val)| Sequel::SQL::Function.new(:IIF, cond, val, exp)})
end

#cast_sql_append(sql, expr, type) ⇒ Object

Access doesn’t support CAST, it uses separate functions for type conversion



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# File 'lib/sequel/adapters/shared/access.rb', line 120

def cast_sql_append(sql, expr, type)
  sql << CAST_TYPES.fetch(type, type).to_s
  sql << PAREN_OPEN
  literal_append(sql, expr)
  sql << PAREN_CLOSE
end

#complex_expression_sql_append(sql, op, args) ⇒ Object 



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# File 'lib/sequel/adapters/shared/access.rb', line 127

def complex_expression_sql_append(sql, op, args)
  case op
  when :ILIKE
    complex_expression_sql_append(sql, :LIKE, args)
  when :'NOT ILIKE'
    complex_expression_sql_append(sql, :'NOT LIKE', args)
  when :LIKE, :'NOT LIKE'
    sql << PAREN_OPEN
    literal_append(sql, args.at(0))
    sql << SPACE << op.to_s << SPACE
    literal_append(sql, args.at(1))
    sql << PAREN_CLOSE
  when :'!='
    sql << PAREN_OPEN
    literal_append(sql, args.at(0))
    sql << NOT_EQUAL
    literal_append(sql, args.at(1))
    sql << PAREN_CLOSE
  when :'%', :'||'
    sql << PAREN_OPEN
    c = false
    op_str = OPS[op]
    args.each do |a|
      sql << op_str if c
      literal_append(sql, a)
      c ||= true
    end
    sql << PAREN_CLOSE
  when :**
    sql << PAREN_OPEN
    literal_append(sql, args[0])
    sql << ' ^ '
    literal_append(sql, args[1])
    sql << PAREN_CLOSE
  when :extract
    part = args.at(0)
    raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part]
    sql << DATEPART_OPEN << format.to_s << COMMA
    literal_append(sql, args.at(1))
    sql << PAREN_CLOSE
  else
    super
  end
end

#constant_sql_append(sql, constant) ⇒ Object

Use Date() and Now() for CURRENT_DATE and CURRENT_TIMESTAMP



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# File 'lib/sequel/adapters/shared/access.rb', line 173

def constant_sql_append(sql, constant)
  case constant
  when :CURRENT_DATE
    sql << DATE_FUNCTION
  when :CURRENT_TIMESTAMP
    sql << NOW_FUNCTION
  when :CURRENT_TIME
    sql << TIME_FUNCTION
  else
    super
  end
end

#cross_join(table) ⇒ Object

Emulate cross join by using multiple tables in the FROM clause.



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# File 'lib/sequel/adapters/shared/access.rb', line 187

def cross_join(table)
  clone(:from=>@opts[:from] + [table])
end

#escape_like(string) ⇒ Object

Access uses [] to escape metacharacters, instead of backslashes.



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# File 'lib/sequel/adapters/shared/access.rb', line 192

def escape_like(string)
  string.gsub(/[\\*#?\[]/){|m| "[#{m}]"}
end

#into(table) ⇒ Object

Specify a table for a SELECT … INTO query.



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# File 'lib/sequel/adapters/shared/access.rb', line 197

def into(table)
  clone(:into => table)
end

#supports_derived_column_lists? ⇒ Boolean

Access does not support derived column lists.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/access.rb', line 202

def supports_derived_column_lists?
  false
end

#supports_intersect_except? ⇒ Boolean

Access doesn’t support INTERSECT or EXCEPT

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/access.rb', line 207

def supports_intersect_except?
  false
end

#supports_is_true? ⇒ Boolean

Access does not support IS TRUE

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/access.rb', line 212

def supports_is_true?
  false
end

#supports_join_using? ⇒ Boolean

Access doesn’t support JOIN USING

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/access.rb', line 217

def supports_join_using?
  false
end

#supports_multiple_column_in? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/access.rb', line 222

def supports_multiple_column_in?
  false
end

#truncate ⇒ Object

Access doesn’t support truncate, so do a delete instead.



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# File 'lib/sequel/adapters/shared/access.rb', line 227

def truncate
  delete
  nil
end