null

问题 This stems from a previous question I asked - about a write conflict with a form, but the problem seems to be originating from the fact that I can update existing records in a linked table provided by one System DSN, but not another linked table provided by another DSN (different database) - allowing me to enter records at first, but then preventing me from making any changes to the records as if another user has changed the data before me. There are no check constraints defined on the server

问题 This is my code: class Person def initialize(first_name, last_name, age) @first_name = first_name @last_name = last_name @age = age end def first_name puts @first_name end def last_name puts @last_name end def age puts @age end end class Musician < Person def initialize(first_name, last_name, age, instrument) @first_name = first_name @last_name = last_name @age = age @instrument = instrument end def instrument puts @instrument end end Then when I try to do the following: m = Musician.new(

问题 On my application, i'm using the login from the Steam API. When the user authenticate on steam, the app create a new user if he doesn't exists on the database, else he bring the user data. In this process, even if i create or just select the user info, i get an array from the user, and i do the Auth::login($user, true); . On this function it works, if i debug the Auth::user() he returns correctly. On the view i can use the Auth::guest() too and it works. But if i go to another page, that only

问题 I need to display Employee last_name and their commission amount from employees table in Oracle SQL, but the condition is if it encounter NULL value I need to print "No Commission" . For the first part I wrote: select last_name, commission_pct from employees; But I am unable to get how to replace NULL values with "No Commission" . 回答1: You can use case expression: select last_name , case when commision_pct is null then 'No Commission' else commision_pct end from employees; or coalesce :

问题 When I run the program this function is in I get a cryptic error that doesn't make sense to me. I wasn't aware I was running a method on a null-valued expression. It occures to me that this is either a scope issue or a value is not getting set. I however have not been able to figure it out and put it out to the community: You cannot call a method on a null-valued expression. At C:\Users\Administrator\Desktop\DCB Settings Modification\DCBxPowershell.ps1:747 char:21 + If ($resetAdapter -eq

问题 Microsoft SQL SERVER: I am working on a skills matrix problem. The example below is a simplified scenario. A company has a factory with two job titles: Apprentice (APP) and Expert (EXP). You can see in the jobskills table that Apprentices must be able to Cut, Drill, and Bend (10, 20, 30). Experts should be able to Cut, Drill, Bend, Weld, and Turn on a lathe (10 thru 50). jobskills table: job_code skill_desc skill_ID -------- ---------- -------- APP Cut 10 APP Drill 20 APP Bend 30 EXP Cut 10

问题 I am looping a method which returns DocumentFile for 100 or even more times . Many times the method returns null while it has already been looped for around 35 times. This is the method which is being looped. public static DocumentFile documentfile(final File file ) { for (UriPermission permissionUri :con.getContentResolver().getPersistedUriPermissions()) { DocumentFile rootDocFile = DocumentFile.fromTreeUri(con, permissionUri.getUri()); String[] parts = (file.getPath()).split("\\/"); for

问题 // Sets all the letters as uppercase var str = ae_a_asset_e$manufacture_code.toUpperCase(); var str2 = ae_a_asset_e$serial_no.toUpperCase(); var str3 = ae_a_asset_e$manu_part_number.toUpperCase(); var str4 = ae_a_asset_e$region_code.toUpperCase(); var str5 = ae_a_asset_e$fac_id.toUpperCase(); Any idea how to fix this? I would think there would have to be a way to say if value = null then don't worry about it. 回答1: First you have to think whether it is correct that some values are null or not,

问题 This question already has an answer here : Closed 7 years ago . Possible Duplicate: How to eliminate NULL fields in TSQL I am using SSMS 2008 R2 and am developing a TSQL query. I want just 1 record / profile_name. Because some of these values are NULL, I am currently doing LEFT JOINS on most of the tables. But the problem with the LEFT JOINs is that now I get > 1 record for some profile_names! But if I change this to INNER JOINs then some profile_names are excluded entirely because they have

问题 I am trying to be able to move the 'giraffe' image view. It seems as though something is wrong with the way im calling the resource from the strings.xml or something it keeps coming back as NullPointerException on the giraffe.setOnTouchListener(this);. Here is the code: public class MainGameActivity extends Activity implements OnTouchListener { float x,y,dx,dy; ImageView giraffe; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this