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Sequel::SQLite::DatasetMethods

Instance methods for datasets that connect to an SQLite database

Public Instance Methods

cast_sql_append(sql, expr, type) click to toggle source
# File lib/sequel/adapters/shared/sqlite.rb, line 521
def cast_sql_append(sql, expr, type)
  if type == Time or type == DateTime
    sql << DATETIME_OPEN
    literal_append(sql, expr)
    sql << PAREN_CLOSE
  elsif type == Date
    sql << DATE_OPEN
    literal_append(sql, expr)
    sql << PAREN_CLOSE
  else
    super
  end
end
complex_expression_sql_append(sql, op, args) click to toggle source

SQLite doesn't support a NOT LIKE b, you need to use NOT (a LIKE b). It doesn't support xor or the extract function natively, so those have to be emulated.

# File lib/sequel/adapters/shared/sqlite.rb, line 537
def complex_expression_sql_append(sql, op, args)
  case op
  when :"NOT LIKE", :"NOT ILIKE"
    sql << NOT_SPACE
    complex_expression_sql_append(sql, (op == :"NOT ILIKE" ? :ILIKE : :LIKE), args)
  when :^
    complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.lit(["((~(", " & ", ")) & (", " | ", "))"], a, b, a, b)}
  when :extract
    part = args.at(0)
    raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part]
    sql << EXTRACT_OPEN << format << COMMA
    literal_append(sql, args.at(1))
    sql << EXTRACT_CLOSE << (part == :second ? NUMERIC : INTEGER) << PAREN_CLOSE
  else
    super
  end
end
constant_sql_append(sql, constant) click to toggle source

SQLite has CURRENT_TIMESTAMP and related constants in UTC instead of in localtime, so convert those constants to local time.

# File lib/sequel/adapters/shared/sqlite.rb, line 557
def constant_sql_append(sql, constant)
  if c = CONSTANT_MAP[constant]
    sql << c
  else
    super
  end
end
delete() click to toggle source

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.

# File lib/sequel/adapters/shared/sqlite.rb, line 568
def delete
  @opts[:where] ? super : where(1=>1).delete
end
explain(opts=nil) click to toggle source

Return an array of strings specifying a query explanation for a SELECT of the current dataset. Currently, the options are ignore, but it accepts options to be compatible with other adapters.

# File lib/sequel/adapters/shared/sqlite.rb, line 575
def explain(opts=nil)
  # Load the PrettyTable class, needed for explain output
  Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable)

  ds = db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}")
  rows = ds.all
  Sequel::PrettyTable.string(rows, ds.columns)
end
having(*cond) click to toggle source

HAVING requires GROUP BY on SQLite

# File lib/sequel/adapters/shared/sqlite.rb, line 585
def having(*cond)
  raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group]
  super
end
quoted_identifier_append(sql, c) click to toggle source

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

# File lib/sequel/adapters/shared/sqlite.rb, line 591
def quoted_identifier_append(sql, c)
  sql << BACKTICK << c.to_s.gsub(BACKTICK_RE, DOUBLE_BACKTICK) << BACKTICK
end
select(*cols) click to toggle source

When a qualified column is selected on SQLite and the qualifier is a subselect, the column name used is the full qualified name (including the qualifier) instead of just the column name. To get correct column names, you must use an alias.

# File lib/sequel/adapters/shared/sqlite.rb, line 599
def select(*cols)
  if ((f = @opts[:from]) && f.any?{|t| t.is_a?(Dataset) || (t.is_a?(SQL::AliasedExpression) && t.expression.is_a?(Dataset))}) || ((j = @opts[:join]) && j.any?{|t| t.table.is_a?(Dataset)})
    super(*cols.map{|c| alias_qualified_column(c)})
  else
    super
  end
end
supports_cte?(type=:select) click to toggle source

SQLite 3.8.3+ supports common table expressions.

# File lib/sequel/adapters/shared/sqlite.rb, line 608
def supports_cte?(type=:select)
  db.sqlite_version >= 30803
end
supports_derived_column_lists?() click to toggle source

SQLite does not support table aliases with column aliases

# File lib/sequel/adapters/shared/sqlite.rb, line 613
def supports_derived_column_lists?
  false
end
supports_intersect_except_all?() click to toggle source

SQLite does not support INTERSECT ALL or EXCEPT ALL

# File lib/sequel/adapters/shared/sqlite.rb, line 618
def supports_intersect_except_all?
  false
end
supports_is_true?() click to toggle source

SQLite does not support IS TRUE

# File lib/sequel/adapters/shared/sqlite.rb, line 623
def supports_is_true?
  false
end
supports_multiple_column_in?() click to toggle source

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

# File lib/sequel/adapters/shared/sqlite.rb, line 628
def supports_multiple_column_in?
  false
end
supports_timestamp_timezones?() click to toggle source

SQLite supports timezones in literal timestamps, since it stores them as text. But using timezones in timestamps breaks SQLite datetime functions, so we allow the user to override the default per database.

# File lib/sequel/adapters/shared/sqlite.rb, line 635
def supports_timestamp_timezones?
  db.use_timestamp_timezones?
end
supports_where_true?() click to toggle source

SQLite cannot use WHERE 't'.

# File lib/sequel/adapters/shared/sqlite.rb, line 640
def supports_where_true?
  false
end

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