    mysql&gt; drop database DB_NAME; 
    ERROR 1010 (HY000): Error dropping database 
    (can&#39;t rmdir &#39;./DB_NAME&#39;, errno: 66)

 

 1. Find the database directory:
`mysql -e &quot;select @@datadir&quot;` -&gt; `/usr/local/mysql/data/`

 2. Go to the DataBase folder: `cd /usr/local/mysql/data/ `

 3. Delete DB folder of the DB with the issue (in this case: `sudo rm -rf DB_NAME`)

If you are using XAMPP in OSX the data directory would be at

    /Applications/XAMPP/xamppfiles/var/mysql

FYI for mac users with normal mysql server: 

    /usr/local/mysql/bin/mysql -u root -pPASSWORD  -e &quot;select @@datadir&quot;

Consider the following PowerShell snippet:

    $csharpString = @&quot;
    using System;

    public sealed class MyClass
    {
        public MyClass() { }
        public override string ToString() {
            return &quot;This is my class. There are many others &quot; +
                &quot;like it, but this one is mine.&quot;;
        }
    }
    &quot;@
    Add-Type -TypeDefinition $csharpString;
    $myObject = New-Object MyClass
    Write-Host $myObject.ToString();

If I run it more than once in the same AppDomain (e.g. run the script twice in powershell.exe or powershell_ise.exe) I get the following error:

    Add-Type : Cannot add type. The type name &#39;MyClass&#39; already exists.
    At line:13 char:1
    + Add-Type -TypeDefinition $csharpString;
    + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        + CategoryInfo          : InvalidOperation: (MyClass:String) [Add-Type],
     Exception
        + FullyQualifiedErrorId :
     TYPE_ALREADY_EXISTS,Microsoft.PowerShell.Commands.AddTypeCommand

How do I wrap the call to [Add-Type](http://ss64.com/ps/add-type.html) -TypeDefinition so that its only called once? 

How do I conditionally add a class with Add-Type -TypeDefinition if it isn&#39;t added already?

I&#39;m new to C/C++ programming, but I&#39;ve been programming in C# for 1.5 years now. I like C# and I like the List class, so I thought about making a List class in C++ as an exercise.

    List&lt;int&gt; ls;
    int whatever = 123;
    ls.Add(1);
    ls.Add(235445);
    ls.Add(whatever);
    
The implementation is similar to any Array List class out there. I have a `T* vector` member where I store the items, and when this storage is about to be completely filled, I resize it. 

Please notice that this is not to be used in production, this is only an exercise. I&#39;m well aware of `vector&lt;T&gt;` and friends.

Now I want to loop through the items of my list. I don&#39;t like to use `for(int i=0;i&lt;n; i==)`. I typed `for` in the visual studio, awaited for Intellisense, and it suggested me this:
	
    for each (object var in collection_to_loop)
    {

    }        

This obviously won&#39;t work with my List implementation. I figured I could do some macro magic, but this feels like a huge hack. Actually, what bothers me the most is passing the type like that:
      
    #define foreach(type, var, list)\
    int _i_ = 0;\
    ##type var;\
    for (_i_ = 0, var=list[_i_]; _i_&lt;list.Length();_i_++,var=list[_i_]) 

    foreach(int,i,ls){
        doWork(i);
    }

My question is: is there a way to make this custom List class work with a `foreach-like` loop?

How to make the for each loop function in C++ work with a custom class

Consider:

    DROP DATABASE db_name;
    ERROR 1010 (HY000): Error dropping database (can&#39;t rmdir &#39;./db_name&#39;, errno: 66)

The problem is that I don&#39;t know where the file/directory is located - this file is missing in **/usr/local/mysql/bin/**...

How do I fix this issue?


Drop database return &quot;Error dropping database errno: 66&quot; in MySQL

Consider:
<pre><code class="hljs language-vbnet">DROP DATABASE db_name;
ERROR 1010 (HY000): Error dropping database (can't rmdir './db_name', errno: 66)
</code></pre>
The problem is that I don't know where the file/directory is located - this file is missing in /usr/local/mysql/bin/...
How do I fix this issue?

How do I change the MySQL root password and username in ubuntu server?  Do I need to stop the mysql service before setting any changes? 

I have a phpmyadmin setup as well, will phpmyadmin get updated automatically?

MySQL: How to reset or change the MySQL root password?

In a table xyz I have a row called components and a labref row which has labref number as shown here
    
Table xyz

    labref             component
    NDQA201303001          a
    NDQA201303001          a
    NDQA201303001          a
    NDQA201303001          a
    NDQA201303001          b
    NDQA201303001          b
    NDQA201303001          b
    NDQA201303001          b
    NDQA201303001          c
    NDQA201303001          c
    NDQA201303001          c
    NDQA201303001          c

I want to group the components then count the rows returned which equals to 3, I have written the below SQL query but it does not help achieve my goal instead it returns 4 for each component

    SELECT DISTINCT component, COUNT( component ) 
    FROM `xyz`
    WHERE labref = &#39;NDQA201303001&#39;
    GROUP BY component

The query returns

Table xyz


    labref         component   COUNT(component)       
    NDQA201303001   a           4
    NDQA201303001   b           4
    NDQA201303001   c           4

 
What I want to achieve now is that from the above result, the rows are counted and 3  is returned as the number of rows, Any workaround is appreciated


Counting number of grouped rows in mysql

If I have three columns:

    orderNumber, name, email

and I would like to count how many unique emails are in the table how would I go about doing so?

A statement like:

    SELECT count(email) FROM orders

gives me the total count.

I tried `SELECT DISTINCT count(email) FROM orders`

but that does not seem to be giving me the numbers I am expecting.

Count number of unique values

How do I write an SQL query to count the total number of a specific num value in the num column of a table?

Assuming we have the following data.

|NAME|NUM|
|-|-|
|SAM|1|
|BOB|1|
|JAKE|2|
|JOHN|4|

Take the following query:
```sql
SELECT WHERE num = 1;
```
This would return these two rows.

|NAME|NUM|
|-|-|
|SAM|1|
|BOB|1|

Count how many rows have the same value

Like the `--disable-column-names` option, do we have an option to get the SQL query without the table format? For example:

```
mysql -u username -p password  --disable-column-names --execute &quot;select name from test&quot;
```

results below:

    -----
    | A |
    | B |
    | C |
    | D |
    -----

Is it possible to get the query result using some sql program option modifiers as below, **without the table format**?

I want this:

    A
    B
    C
    D


Get the SQL query result without the table format

It works ok as a single tool:

    curl &quot;someURL&quot;
    curl -o - &quot;someURL&quot;

but it doesn&#39;t work in a pipeline:

    curl &quot;someURL&quot; | tr -d &#39;\n&#39;
    curl -o - &quot;someURL&quot; | tr -d &#39;\n&#39;

it returns:

    (23) Failed writing body

What is the problem with piping the cURL output? How to buffer the whole cURL output and then handle it?

Why does cURL return error &quot;(23) Failed writing body&quot;?

I am using the z Shell (`zsh`) instead of the default bash, and something wrong happen so that all commands that used to work are no longer recognized:

    ls
    zsh: command not found: ls

    open -e .zshrc
    zsh: correct &#39;open&#39; to &#39;_open&#39; [nyae]? 


I don&#39;t know how to reset `zsh` or how to fix this. Here is the content of `$PATH` variable:

    echo $PATH
    /Users/Malloc/bin/Sencha/Cmd/3.1.2.342:/usr/local/bin/mate


I cannot open the `.bash_profile` file nor `.zshrc` file, seems the only solution is to reset the `zsh`. Any ideas? 


**EDIT:**

I even tried to reset `zsh` as indicated in [this thread][1], but always got `command not found` error:

    exec zsh
    zsh: command not found: zsh


So what&#39;s going on? Why all commands are lost?

  [1]: https://unix.stackexchange.com/questions/14885/how-to-reset-a-shell-environment

commands not found on zsh

I am continuously receiving this error.

I am using mySQL Workbench and from what I am finding is that root&#39;s schema privileges are null. There are no privileges at all.

I am having troubles across platforms that my server is used for and this has been all of a sudden issue.

**root@127.0.0.1** apparently has a lot of access but I am logged in as that, but it just assigns to localhost anyways - localhost has no privileges.  

I have done a few things like `FLUSH HOSTS`, `FLUSH PRIVILEGES`, etc
but have found no success from that or the internet.

How can I get root its access back? I find this frustrating because when I look around people expect you to &quot;have access&quot; but I don&#39;t have access so I can&#39;t go into command line or anything and `GRANT` myself anything.

When running `SHOW GRANTS FOR root` this is what I get in return:

&gt; Error Code: 1141. There is no such grant defined for user &#39;root&#39; on
&gt; host &#39;%&#39;

Access Denied for User &#39;root&#39;@&#39;localhost&#39; (using password: YES) - No Privileges?

I&#39;m writing a script that requires root level permissions, and I want to make it so that if the script is not run as root, it simply echoes &quot;Please run as root.&quot; and exits.

Here&#39;s some pseudocode for what I&#39;m looking for:

    if (whoami != root)
      then echo &quot;Please run as root&quot;
     
      else (do stuff)
    fi

    exit

How could I best (cleanly and securely) accomplish this? Thanks!

Ah, just to clarify: the (do stuff) part would involve running commands that in-and-of themselves require root. So running it as a normal user would just come up with an error. This is just meant to cleanly run a script that requires root commands, without using sudo inside the script, I&#39;m just looking for some syntactic sugar. 

How to check if running as root in a bash script

I&#39;m happily using SLF4J with logback and use **2 appenders** for the **ROOT** logger.

    &lt;root level=&quot;DEBUG&quot;&gt;
    	&lt;appender-ref ref=&quot;STDOUT&quot; /&gt;
    	&lt;appender-ref ref=&quot;FILE&quot; /&gt;
    &lt;/root&gt;

**How could we have different log-levels for both appenders? I still need all ROOT-logger messages.**

 - *DEBUG*-level for STDOUT
 - *INFO*-level for FILE

All log&#39;s need to be part of the output (so the ROOT logger is needed).

How to create 2 different ROOT loggers with logback?

I have an Android-based phone (2.3.6) with unlocked root privileges.
Since i&#39;d like to have access to my phone through my computer, today i&#39;ve installed QtAdb and Android SDK.
If i open a command prompt and i do

&gt; adb shell su

i get

&gt; #

And so I am able to copy, remove, push files on my phone (on the phone i get a notification using the app &quot;SuperSU&quot;.)

But if i launch QtAdb - under Windows 7 - i get the following error: &quot;adbd cannot run as root in production builds&quot;. I miss something? There&#39;s something wrong with QtAdb?

Android: adbd cannot run as root in production builds

I rooted my unlocked Galaxy S3 (SGH-T999)

Now, I&#39;m trying to run `adb root` from Windows *Command Prompt*, however, I&#39;m getting `adbd cannot run as root in production builds` error. So, the very first thing I checked was whether my phone was really rooted?

So I tried the following:

Open Command prompt

    $adb devices // lists my device
    $adb shell //goes to shell
    $su // opens a &#39;SuperSu&#39; prompt on my phone and I &#39;Grant&#39; permission
    # // Before following the rooting instructions, I was getting &#39;no su command found&#39; in the previous step. So, I believe my phone is ROOTED. **Correct me if I&#39;m wrong.**

However, when I do `adb root`, I get `adbd cannot run as root in production builds` error.
So, I thought, I might have to do some additional stuff beyond what I did above. I tried all the solutions in the following SO questions:

 - https://stackoverflow.com/questions/8761992/launch-a-script-as-root-through-adb
 - https://stackoverflow.com/questions/13089694/adb-remount-permission-denied-but-able-to-access-super-user-in-shell-android
 - https://stackoverflow.com/questions/18369144/unable-to-run-adb-root-on-a-rooted-android-phone

None of the above worked for me. All they do is give the ROOT access INSIDE of SHELL. I want `adb root` to work so that I can execute various adb commands WITHOUT going into shell.



Content Type	Original Author	Original Content on Stackoverflow
Question	user984621	View Question on Stackoverflow
Solution 1 - Mysql	Hackerman	View Answer on Stackoverflow
Solution 2 - Mysql	kbokdia	View Answer on Stackoverflow
Solution 3 - Mysql	Bjørson Bjørson	View Answer on Stackoverflow

Drop database return "Error dropping database errno: 66" in MySQL

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

Solution 3 - Mysql

How to make the for each loop function in C++ work with a custom class

How do I conditionally add a class with Add-Type -TypeDefinition if it isn't added already?

Attributions