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问题 I have an oracle table like this: create table tms_transaction_tbl ( trans_id number primary key, location_id number, trans_date date, resource_id number, ts_id number, max_value number, booked_units number default 0, remaining number default (select max_value-booked_units), booked number not null , user_id number, trans_time timestamp ); as you can see I tried to set default value of remaining to (max_value-booked_units) remainging number default (select max_value-booked_units), but it gives

问题 I am trying to remove an ImageButton's background in only the default state. I'd like the pressed and selected states to behave as usual so that they look correct on different devices, which use different colors for the pressed and selected states. Is there any way to set an ImageButton's background default state's drawable without affecting the pressed and selected states? I've tried to do this with a selector, but it does not appear to allow you to use the default drawables for some states

问题 I am trying to remove an ImageButton's background in only the default state. I'd like the pressed and selected states to behave as usual so that they look correct on different devices, which use different colors for the pressed and selected states. Is there any way to set an ImageButton's background default state's drawable without affecting the pressed and selected states? I've tried to do this with a selector, but it does not appear to allow you to use the default drawables for some states

问题 I've been trying to find a way to skip a template parameter not located at the end of the template parameter list, in a derived class that has been assigned a default in its base class. I've done some research on this topic, also here on SO. While similar questions have been discussed on SO - many answers basically suggesting it doesn't work were related to very special cases like the hash map case here. Also I found this answer by "Potatoswatter", which in my opinion contradicts the

问题 I've defined multiple constructors, with some default argument values in all of them. Looks correct (I can't see any ambiguity), but Scala (2.8) compiler complains: multiple overloaded alternatives of constructor define default arguments Does it mean that I can't define default values for overloaded constructors at all? Let me illustrate the situation (primitivized, of course, but illustrative): class A(subject : Double, factor : Int = 1, doItRight : Boolean = true) { def this (subject : Int,

问题 I've defined multiple constructors, with some default argument values in all of them. Looks correct (I can't see any ambiguity), but Scala (2.8) compiler complains: multiple overloaded alternatives of constructor define default arguments Does it mean that I can't define default values for overloaded constructors at all? Let me illustrate the situation (primitivized, of course, but illustrative): class A(subject : Double, factor : Int = 1, doItRight : Boolean = true) { def this (subject : Int,

问题 I'd like to plot multiple plots in separate bitmap files using the file name pattern (for example, for JPEG) file.%03d.jpg in R. I tried using something like: somevar <- 1 jpg(paste(sep='',filename,'.%03d.jpg')) while(somevar <= n) { plot(data[somevar]) dev.new() somevar <- somevar + 1 } dev.off() but it creates one .jpg file and several Rplotnnn.pdf files. How can I change the default device to jpg , and use the custom file name pattern? 回答1: I think this should work somevar <- 1 while

问题 My app is retaining all of the variable values when it closes and this is effecting how it runs when reopened. Is there any way to reset them all upon app close? or is there a way to clean the app from memory when it is closed so to speak? For the moment I have just been setting all of the important variables "=0" in the last few lines of execution but I know there must be a correct way to doing this. EDIT: OK I thought that it would just be easier to reply here instead of individually to

问题 How should I obtain the ip address of default gateway ? Rather than read entries from /proc , is there any standalone API useable ? 回答1: you can use libnl which is a library to communicate with the kernel via NETLINK sockets. a simple example to get the default route would be (please add error checking and the needed headers) void cb_route (struct nl_object *cb, void *arg) { struct rtnl_route *route = (struct rtnl_route*) cb; /* do what you need to do with rtnl_route object * e.g. copy it to

问题 I have a select field that have have present options and I have a php script check a mysql database and add a select tag to the one currently being used. I need to find a way to know if the user have changed the select field or not before submitting it. var Access = document.forms[UIDF]["Access"].value; var DAccess = document.forms[UIDF]["Access"].defaultIndex; <--- This is my problem. I just need to know how to get the selected option value as this keep changing with every user <select name=