Interpreting a GET

[Gil Dawson <Gil@xxxxxxxxxxxxx>]

This critter appears in my log sometimes:

113.161.88.70 - - [24/Aug/2014:00:29:49 -0700] "GET /?C=D;O=A'+union+select+char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33)+--+ HTTP/1.1" 200 5630

Apache apparently understands it (and returns 200 5630).  I didn't find "char(" in RFC2616 nor a Google Search of the Apache documentation.

Any idea what it is?

--Gil