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require 'sqlite3/errors'
require 'sqlite3/resultset'
class String
def to_blob
SQLite3::Blob.new( self )
end
end
module SQLite3
# A statement represents a prepared-but-unexecuted SQL query. It will rarely
# (if ever) be instantiated directly by a client, and is most often obtained
# via the Database#prepare method.
class Statement
include Enumerable
# This is any text that followed the first valid SQL statement in the text
# with which the statement was initialized. If there was no trailing text,
# this will be the empty string.
attr_reader :remainder
# Binds the given variables to the corresponding placeholders in the SQL
# text.
#
# See Database#execute for a description of the valid placeholder
# syntaxes.
#
# Example:
#
# stmt = db.prepare( "select * from table where a=? and b=?" )
# stmt.bind_params( 15, "hello" )
#
# See also #execute, #bind_param, Statement#bind_param, and
# Statement#bind_params.
def bind_params( *bind_vars )
index = 1
bind_vars.flatten.each do |var|
if Hash === var
var.each { |key, val| bind_param key, val }
else
bind_param index, var
index += 1
end
end
end
# Execute the statement. This creates a new ResultSet object for the
# statement's virtual machine. If a block was given, the new ResultSet will
# be yielded to it; otherwise, the ResultSet will be returned.
#
# Any parameters will be bound to the statement using #bind_params.
#
# Example:
#
# stmt = db.prepare( "select * from table" )
# stmt.execute do |result|
# ...
# end
#
# See also #bind_params, #execute!.
def execute( *bind_vars )
reset! if active? || done?
bind_params(*bind_vars) unless bind_vars.empty?
@results = ResultSet.new(@connection, self)
step if 0 == column_count
yield @results if block_given?
@results
end
# Execute the statement. If no block was given, this returns an array of
# rows returned by executing the statement. Otherwise, each row will be
# yielded to the block.
#
# Any parameters will be bound to the statement using #bind_params.
#
# Example:
#
# stmt = db.prepare( "select * from table" )
# stmt.execute! do |row|
# ...
# end
#
# See also #bind_params, #execute.
def execute!( *bind_vars, &block )
execute(*bind_vars)
block_given? ? each(&block) : to_a
end
# Returns true if the statement is currently active, meaning it has an
# open result set.
def active?
!done?
end
# Return an array of the column names for this statement. Note that this
# may execute the statement in order to obtain the metadata; this makes it
# a (potentially) expensive operation.
def columns
get_metadata unless @columns
return @columns
end
def each
loop do
val = step
break self if done?
yield val
end
end
# Return an array of the data types for each column in this statement. Note
# that this may execute the statement in order to obtain the metadata; this
# makes it a (potentially) expensive operation.
def types
must_be_open!
get_metadata unless @types
@types
end
# Performs a sanity check to ensure that the statement is not
# closed. If it is, an exception is raised.
def must_be_open! # :nodoc:
if closed?
raise SQLite3::Exception, "cannot use a closed statement"
end
end
private
# A convenience method for obtaining the metadata about the query. Note
# that this will actually execute the SQL, which means it can be a
# (potentially) expensive operation.
def get_metadata
@columns = Array.new(column_count) do |column|
column_name column
end
@types = Array.new(column_count) do |column|
column_decltype column
end
end
end
end
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