259 lines
8.2 KiB
Ruby
259 lines
8.2 KiB
Ruby
#--
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# =============================================================================
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# Copyright (c) 2004, Jamis Buck (jgb3@email.byu.edu)
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# * Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# * Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# * The names of its contributors may not be used to endorse or promote
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# products derived from this software without specific prior written
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# permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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# =============================================================================
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#++
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require 'sqlite3/errors'
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require 'sqlite3/resultset'
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class String
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def to_blob
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SQLite3::Blob.new( self )
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end
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end
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module SQLite3
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# A class for differentiating between strings and blobs, when binding them
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# into statements.
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class Blob < String; end
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# A statement represents a prepared-but-unexecuted SQL query. It will rarely
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# (if ever) be instantiated directly by a client, and is most often obtained
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# via the Database#prepare method.
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class Statement
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# This is any text that followed the first valid SQL statement in the text
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# with which the statement was initialized. If there was no trailing text,
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# this will be the empty string.
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attr_reader :remainder
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# The underlying opaque handle used to access the SQLite @driver.
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attr_reader :handle
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# Create a new statement attached to the given Database instance, and which
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# encapsulates the given SQL text. If the text contains more than one
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# statement (i.e., separated by semicolons), then the #remainder property
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# will be set to the trailing text.
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def initialize( db, sql, utf16=false )
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@db = db
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@driver = @db.driver
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@closed = false
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@results = @columns = nil
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result, @handle, @remainder = @driver.prepare( @db.handle, sql )
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Error.check( result, @db )
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end
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# Closes the statement by finalizing the underlying statement
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# handle. The statement must not be used after being closed.
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def close
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must_be_open!
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@closed = true
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@driver.finalize( @handle )
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end
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# Returns true if the underlying statement has been closed.
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def closed?
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@closed
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end
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# Binds the given variables to the corresponding placeholders in the SQL
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# text.
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#
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# See Database#execute for a description of the valid placeholder
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# syntaxes.
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#
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# Example:
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#
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# stmt = db.prepare( "select * from table where a=? and b=?" )
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# stmt.bind_params( 15, "hello" )
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#
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# See also #execute, #bind_param, Statement#bind_param, and
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# Statement#bind_params.
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def bind_params( *bind_vars )
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index = 1
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bind_vars.flatten.each do |var|
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if Hash === var
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var.each { |key, val| bind_param key, val }
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else
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bind_param index, var
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index += 1
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end
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end
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end
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# Binds value to the named (or positional) placeholder. If +param+ is a
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# Fixnum, it is treated as an index for a positional placeholder.
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# Otherwise it is used as the name of the placeholder to bind to.
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#
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# See also #bind_params.
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def bind_param( param, value )
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must_be_open!
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reset! if active?
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if Fixnum === param
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case value
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when Bignum then
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@driver.bind_int64( @handle, param, value )
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when Integer then
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@driver.bind_int( @handle, param, value )
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when Numeric then
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@driver.bind_double( @handle, param, value.to_f )
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when Blob then
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@driver.bind_blob( @handle, param, value )
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when nil then
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@driver.bind_null( @handle, param )
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else
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@driver.bind_text( @handle, param, value )
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end
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else
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param = param.to_s
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param = ":#{param}" unless param[0] == ?:
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index = @driver.bind_parameter_index( @handle, param )
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raise Exception, "no such bind parameter '#{param}'" if index == 0
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bind_param index, value
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end
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end
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# Execute the statement. This creates a new ResultSet object for the
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# statement's virtual machine. If a block was given, the new ResultSet will
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# be yielded to it; otherwise, the ResultSet will be returned.
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#
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# Any parameters will be bound to the statement using #bind_params.
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#
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# Example:
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#
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# stmt = db.prepare( "select * from table" )
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# stmt.execute do |result|
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# ...
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# end
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#
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# See also #bind_params, #execute!.
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def execute( *bind_vars )
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must_be_open!
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reset! if active?
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bind_params(*bind_vars) unless bind_vars.empty?
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@results = ResultSet.new( @db, self )
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if block_given?
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yield @results
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else
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return @results
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end
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end
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# Execute the statement. If no block was given, this returns an array of
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# rows returned by executing the statement. Otherwise, each row will be
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# yielded to the block.
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#
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# Any parameters will be bound to the statement using #bind_params.
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#
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# Example:
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#
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# stmt = db.prepare( "select * from table" )
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# stmt.execute! do |row|
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# ...
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# end
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#
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# See also #bind_params, #execute.
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def execute!( *bind_vars )
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result = execute( *bind_vars )
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rows = [] unless block_given?
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while row = result.next
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if block_given?
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yield row
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else
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rows << row
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end
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end
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rows
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end
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# Resets the statement. This is typically done internally, though it might
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# occassionally be necessary to manually reset the statement.
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def reset!(clear_result=true)
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@driver.reset(@handle)
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@results = nil if clear_result
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end
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# Returns true if the statement is currently active, meaning it has an
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# open result set.
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def active?
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not @results.nil?
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end
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# Return an array of the column names for this statement. Note that this
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# may execute the statement in order to obtain the metadata; this makes it
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# a (potentially) expensive operation.
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def columns
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get_metadata unless @columns
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return @columns
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end
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# Return an array of the data types for each column in this statement. Note
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# that this may execute the statement in order to obtain the metadata; this
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# makes it a (potentially) expensive operation.
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def types
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get_metadata unless @types
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return @types
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end
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# A convenience method for obtaining the metadata about the query. Note
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# that this will actually execute the SQL, which means it can be a
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# (potentially) expensive operation.
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def get_metadata
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must_be_open!
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@columns = []
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@types = []
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column_count = @driver.column_count( @handle )
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column_count.times do |column|
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@columns << @driver.column_name( @handle, column )
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@types << @driver.column_decltype( @handle, column )
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end
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@columns.freeze
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@types.freeze
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end
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private :get_metadata
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# Performs a sanity check to ensure that the statement is not
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# closed. If it is, an exception is raised.
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def must_be_open! # :nodoc:
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if @closed
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raise SQLite3::Exception, "cannot use a closed statement"
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end
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end
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end
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end
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