这是我的活动sql：
C:\Users\apzal.bahin\Documents\Business Media\Learning\Cucumber calabash\Calabas
hCucumberTest>gem install json -v 1.8.5
Temporarily enhancing PATH to include DevKit...
Building native extensions. This could take a while...
ERROR: Error installing json:
ERROR: Failed to build gem native extension.
current directory: C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/json-1.8.5/ext/jso
n/ext/generator
C:/Ruby22-x64/bin/ruby.exe -r ./siteconf20170113-12584-dvx97z.rb extconf.rb
creating Makefile
current directory: C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/json-1.8.5/ext/json/ex
t/generator
make "DESTDIR=" clean
current directory: C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/json-1.8.5/ext/json/ex
t/generator
make "DESTDIR="
generating generator-x64-mingw32.def
compiling generator.c
make: x86_64-w64-mingw32-gcc: Command not found
make: *** [generator.o] Error 127
make failed, exit code 2
Gem files will remain installed in C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/json-1
.8.5 for inspection.
Results logged to C:/Ruby22-x64/lib/ruby/gems/2.2.0/extensions/x64-mingw32/2.2.0
/json-1.8.5/gem_make.out
然后我需要在流明中使用DB 所以我这样写：
SELECT sag.goods_id, if(sa.status=3, 1, 0) AS act_status
FROM d_seckill_activity_goods AS sag LEFT JOIN d_seckill_activity AS sa ON sa.id = sag.sa_id
WHERE sa.id = 1
幸运的是它运作良好，但我讨厌$ prefix变量，
是使用DB的另一种方式吗？