Sorry guys, i found the problem. It is related to this [post.][1]


  [1]: https://stackoverflow.com/questions/12994919/can-not-create-table-in-workbench-errno-121

Which was hinted by **rakeshjain.**

It may be deleted as a duplicate post by admin.

The answer is, i had two CONTRAINTS on different tables with the same name:

CONSTRAINT **`Update_ID_fk`**  --&gt;  Changed one and problem solved.


I am aware that C/C++ is a lower-level language and generates relatively optimized machine code when we compare with any other high-level language. But I guess there is pretty much more than that, which is also evident from the practice.

When I do simple calculations like montecarlo averaging of a Gaussian sample collection or so, I see there is not much of a difference between a C++ implementation or MATLAB implementation, sometimes in fact MATLAB performs a bit better in time.

When I move on to larger scale simulations with thousands of lines of code, slowly the real picture shows up. C++ simulations show superior performance like 100x better in time complexity than an equivalent MATLAB implementation.

The code in C++ most of the times, is pretty much serial and no hi-fi optimization is done explicitly. Whereas, as per my awareness, MATLAB inherently does a lot of optimization. This shows up for example when I try to generate a huge chunk of random samples, where as the equivalent in C++ using some library like IT++/GSL/Boost performs relatively slower (the algorithm used is the same namely mt19937).

**My question is simply to know if there is a simpler tradeoff between MATLAB/C++ in performance. Is it just like what people say, &quot;Whenever you can, C/C++ is the better&quot;(The frequently experienced)?. In a different perspective, &quot;What is MATLAB good for, other than comfort?&quot;**

By the way, I don&#39;t see coding efficiency parameter being significant here, thinking of the same programmer in both cases.  And also, I think the other alternatives like python,R are not relevant here. But dependence on the specific libraries we use should be interesting.


_[I am a phd student in Coding Theory in communication systems. I do simulations using matlab/C++ all the time, and have reasonable experience of coding few 10K&#39;s of lines in both cases]_

Performance Tradeoff - When is MATLAB better/slower than C/C++

I&#39;m trying to understand whether the different behavior exposed by gcc vs. clang in the output of this simple C++11 program is due to a bug in clang (Xcode 5.0.2, OS X 10.8.5). The code is as follows:

    #include &lt;iostream&gt;
    
    int main() {
    
    
    	int matrix[][3]{{1,2,3}, {4,5,6}, {7,8,9}};
    	auto dyn_matrix = new int[3][3]{{1,2,3}, {4,5,6}, {7,8,9}};
    	
    	std::cout &lt;&lt; matrix[0][1] &lt;&lt; std::endl;
    	std::cout &lt;&lt; dyn_matrix[0][1] &lt;&lt; std::endl;
    	
    	return 0;	
    }

As shown, I&#39;m trying to use uniform initialization to initialize an anonymous (resp. named) multidimensional array of size `3x3`. When compiling with gcc 4.7 from MacPorts the expected output is obtained:

    $g++-mp-4.7 -std=c++11 dyn_matrix.cpp -o dyn_matrix 
    $ ./dyn_matrix
    2
    2
    $

Conversely, in case clang is used the output reads:

    $ clang++ -std=c++11 -stdlib=libc++ dyn_matrix.cpp -o dyn_matrix_clang
    $ ./dyn_matrix_clang 
    2
    4
    $  

In this case the result is (apparently) wrong. `clang --version` reports:

    Apple LLVM version 5.0 (clang-500.2.75) (based on LLVM 3.3svn)
    Target: x86_64-apple-darwin12.5.0
    Thread model: posix

Who&#39;s to blame? me, gcc or clang?

**UPDATE Dec 11th, 2013:** The bug should have been fixed in r196995. Unfortunately, we still do not know how long it will take before Apple updates the version of clang that ships with Xcode. 

**UPDATE Dec 9th, 2013:** I submitted a bug report on the LLVM bugzilla platform. It has indeed been recognized as a bug, a patch is currently under review, see http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20131209/095099.html. 

Thanks.

Different results between gcc and clang when compiling a rather simple c++11 program

                           

Duplicate key on write or update
--------------------------------

First i will like to acknowledge the fact that, i have been to **similar posts**, but i couldn&#39;t find a way to solve this annoying issue which i face as of present.I am using **mysql workbench** and i keep getting this error.

 1. **On workbench :** ERROR: Error 1005: Can&#39;t create table &#39;database.path&#39; (errno: 121)
 
 2. **Use &quot;Perror 121&quot; on command line :** MySQL error code 121: Duplicate key on write or update


At the end of the log, it shows **9 successful operations** and **1 failure** with only **path** table visible in the logs.

Any help and suggestion is welcomed.I think the mysql compiler doesn&#39;t really do a good Job when it comes to signifying the actual issue for debugging. 



Duplicate key on write or update?

<h4 id="duplicate-key-on-write-or-update"><a aria-hidden="true" tabindex="-1" href="#duplicate-key-on-write-or-update"></a>Duplicate key on write or update</h4>
First i will like to acknowledge the fact that, i have been to similar posts, but i couldn't find a way to solve this annoying issue which i face as of present.I am using mysql workbench and i keep getting this error.
<ol>
<li>
On workbench : ERROR: Error 1005: Can't create table 'database.path' (errno: 121)
</li>
<li>
Use "Perror 121" on command line : MySQL error code 121: Duplicate key on write or update
</li>
</ol>
At the end of the log, it shows 9 successful operations and 1 failure with only path table visible in the logs.
Any help and suggestion is welcomed.I think the mysql compiler doesn't really do a good Job when it comes to signifying the actual issue for debugging.

I&#39;m attempting to display an image stored in the BLOB column in the database;

I fetch the data from the database with a SELECT perform no transformations on the data and display it with the following (from a script whose only output is the following):

    header(&quot;Content-Type: image/jpeg&quot;);
    echo $image;

Please note chrome is displaying the content size as the correct size for the image as well as the correct mime type (`image/jpeg`). nothing is echoing out before the header and ive checked the blob in the database is correct. There is also no trailing whitespace before or after the `&lt;?php ?&gt;` tags.

chrome/IE displays an image icon but not the image itself. any ideas?

EDIT: image is got the from the database as such: 

    $sql = &quot;SELECT * FROM products WHERE id = $id&quot;;
    $sth = $db-&gt;query($sql);
    $row = $sth-&gt;fetch();
    $image = $row[&#39;image&#39;];

var_dump($image) gives: 

    string &#39;&#255;&#216;&#255;&#224;�JFIF��x�x��&#255;&#225;�ZExif��MM�*�����������J��������Q�������Q������tQ������t�����† ��&#177;&#255;&#219;�C�		
	
    &#255;&#219;�C&#255;&#192;�_&quot;�&#255;&#196;�����������	
    &#255;&#196;�&#181;���}�!1AQa&quot;q2‘&#161;#B&#177;&#193;R&#209;&#240;$3br‚	
    %&amp;&#39;()*456789:CDEFGHIJSTUVWXYZcdefghijstuvwxyzƒ„…†‡ˆ‰Š’“”•–—˜™š&#162;&#163;&#164;&#165;&#166;&#167;&#168;&#169;&#170;&#178;&#179;    &#180;&#181;&#182;&#183;&#184;&#185;&#186;&#194;&#195;&#196;&#197;&#198;&#199;&#200;&#201;&#202;&#210;&#211;&#212;&#213;&#214;&#215;&#216;&#217;&#218;&#225;&#226;&#227;&#228;&#229;&#230;&#231;&#232;&#233;&#234;&#241;&#242;&#243;&#244;&#245;&#246;&#247;&#248;&#249;&#250;&#255;&#196;��������&#39;... (length=60766)

PHP display image BLOB from MySQL

I currently have a table of `page_views` that records one row for each time a visitor accesses a page, recording the user&#39;s ip/id and the id of the page itself. I should add that the `created_at` column is of type: *timestamp*, so it includes the hours/minutes/seconds. When I try `groupBy` queries, it does not group same days together because of the seconds difference.

    created_at         page_id       user_id
    ==========         =======       =======
    10-11-2013            3            1
    10-12 2013            5            5
    10-13 2013            5            2
    10-13 2013            3            4
      ...                ...          ...

I&#39;d like to get results based on views/day, so I can get something like:

      date          views
      ====          =====
    10-11-2013       15
    10-12 2013       45
      ...            ...


I&#39;m thinking I&#39;ll need to dig into `DB::raw()` queries to achieve this, but any insight would help greatly, thanks


Edit: Added clarification of `created_at` format.


Laravel Eloquent get results grouped by days

I believe that I&#39;ve successfully deployed my (very basic) site to fortrabbit, but as soon as I connect to SSH to run some commands (such as `php artisan migrate` or `php artisan db:seed`) I get an error message:


    [PDOException]
    SQLSTATE[HY000] [2002] No such file or directory

At some point the migration must have worked, because my tables are there - but this doesn&#39;t explain why it isn&#39;t working for me now.

PDOException SQLSTATE[HY000] [2002] No such file or directory

I searched the internet but cannot find anything related to this specific error/table. It pops up when I try to view a table in phpMyAdmin. I am logged in as root and the installation (under ubuntu 13.10) of phpMyAdmin is fresh and untouched so far.

Here is the whole message:

    SELECT `prefs`
    FROM `phpmyadmin`.`pma_table_uiprefs`
    WHERE `username` = &#39;root&#39;
    AND `db_name` = &#39;symfony&#39;
    AND `table_name` = &#39;users&#39;
    
    MySQL reports: #1146 - Table &#39;phpmyadmin.pma_table_uiprefs&#39; doesn&#39;t exist

Is the installation just broken or am I missing something?

phpmyadmin.pma_table_uiprefs doesn&#39;t exist

When I tried running the following command on MySQL from within Terminal:

    mysql -u $user -p$password -e &quot;statement&quot;

The execution works as expected, but it always issues a warning:

&gt; *Warning: Using a password on the command line interface can be insecure.* 

However, I have to conduct the statement above using an environment variable (`$password`) that stores my password, because I want to run the command iteratively in bash script from within Terminal, and I definitely don&#39;t like the idea of waiting a prompt showing up and forcing me to input my password 50 or 100 times in a single script. So here&#39;s my question:

* Is it feasible to suppress the warning? The command works properly as I stated, but the window becomes pretty messy when I loop over and run the command 50 or 100 times.

* Should I obey the warning message and do NOT write my password in my script? If that&#39;s the case, then do I have to type in my password every time the prompt forces me to do so?

Running `man mysql` doesn&#39;t help, saying only 

&gt; `--show-warnings`  
Cause warnings to be shown after each statement if there are any. This option applies to interactive and batch mode.

and mentions nothing about how to turn off the functionality, if I&#39;m not missing something.

I&#39;m on OS X 10.9.1 Mavericks and use MySQL 5.6 from homebrew.

Suppress warning messages using mysql from within Terminal, but password written in bash script

I have a Table (call it `A_table`) in a database (call it `A_db`) in Microsoft SQL Server Management Studio, and there are 10 rows.

I have another database (call it `B_db`), and it has a Table (call it `B_table`), which has the same column settings as `A_table` has. But the `B_table` is empty.

What I want:

 - **Copy** every rows from `A_table` to `B_table`.

Is there any option in **Microsoft SQL Server Management Studio 2012**, to create an insert SQL from a table? Or is there any other option to do that?

How to export all data from table to an insertable sql format?

I want to insert data into 3 tables with a single query.  
My tables looks like below:

    CREATE TABLE sample (
       id        bigserial PRIMARY KEY,
       lastname  varchar(20),
       firstname varchar(20)
    );

    CREATE TABLE sample1(
       user_id    bigserial PRIMARY KEY,
       sample_id  bigint REFERENCES sample,
       adddetails varchar(20)
    );
    
    CREATE TABLE sample2(
       id      bigserial PRIMARY KEY,
       user_id bigint REFERENCES sample1,
       value   varchar(10)
    );

I will get a key in return for every insertion and I need to insert that key in the next table.  
My query is:

    insert into sample(firstname,lastname) values(&#39;fai55&#39;,&#39;shaggk&#39;) RETURNING id;
    insert into sample1(sample_id, adddetails) values($id,&#39;ss&#39;) RETURNING user_id;
    insert into sample2(user_id, value) values($id,&#39;ss&#39;) RETURNING id;

But if I run single queries they just return values to me and I cannot reuse them in the next query immediately.

How to achieve this?

Insert data in 3 tables at a time using Postgres

Postgres 8.4 and greater databases contain common tables in `public` schema and company specific tables in `company` schema.  
`company` schema names always start with `&#39;company&#39;` and end with the company number.  
So there may be schemas like:

    public
    company1
    company2
    company3
    ...
    companynn

An application always works with a single company.  
The `search_path` is specified accordingly in odbc or npgsql connection string, like:

    search_path=&#39;company3,public&#39;

How would you check if a given table exists in a specified `companyn` schema?

eg:

    select isSpecific(&#39;company3&#39;,&#39;tablenotincompany3schema&#39;)

should return `false`, and

    select isSpecific(&#39;company3&#39;,&#39;tableincompany3schema&#39;)

should return `true`.

In any case, the function should check only `companyn` schema passed, not other schemas.

If a given table exists in both `public` and the passed schema, the function should return `true`.  
It should work for Postgres 8.4 or later.

How to check if a table exists in a given schema

    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY)

Why we are using this annotations?
i need to know if this autoincrement my table id values.
(GenerationType.IDENTITY) is there any other types whats actually happening when we use this annotation

   

 

 

    public class Author extends Domain
    {
    	@Id
    	@GeneratedValue(strategy = GenerationType.IDENTITY)
    	@Basic(optional = false)
    	@Column(name = &quot;id&quot;) 
    	private Integer id;
    	
    	@Basic(optional = false)
    	@Column(name = &quot;name&quot;) 
    	private String name;
    	
    	@Column(name = &quot;address&quot;) 
    	private String address; 
    	
    	@OneToMany(cascade = CascadeType.ALL, mappedBy = &quot;authorId&quot;)
    	private List&lt;Book&gt;
    	bookList;
    	   
    	public Author()
    	{ 
    		setServiceClassName(&quot;wawo.tutorial.service.admin.AuthorService&quot;);
    	}
    }


*Is it necessary to extend Domain abstract class?What is the use?

Content Type	Original Author	Original Content on Stackoverflow
Question	user3066913	View Question on Stackoverflow
Solution 1 - Mysql	user3066913	View Answer on Stackoverflow
Solution 2 - Mysql	Vahap Gencdal	View Answer on Stackoverflow

Duplicate key on write or update?

Mysql Problem Overview

Duplicate key on write or update

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

Different results between gcc and clang when compiling a rather simple c++11 program

Performance Tradeoff - When is MATLAB better/slower than C/C++

Attributions