Listed are the steps that could rectify the error:

 1. Press &lt;kbd&gt;Windows&lt;/kbd&gt;+&lt;kbd&gt;R&lt;/kbd&gt;
 2. Type `services.msc` and strike &lt;kbd&gt;Enter&lt;/kbd&gt;
 3. Find all services starting with `ora` start these services and wait!!
 4. When your server specific service is initialized (in my case it was `orcl`) 
 5. Now run `mysql` or whatever you are using and start coding.P

I encountered same problem with ORACLE 11G express on Windows.
After a long time waiting I got the same error message.

My solution is to **make sure the hostname in tnsnames.ora (usually it&#39;s not &quot;localhost&quot;) and the default hostname in sql developer(usually it&#39;s &quot;localhost&quot;) same**. You can either do this by changing it in the tnsnames.ora, or filling up the same in the sql developer.

Oh, of course you need to reboot all the oracle services (just to be safe).

Hope it helps.

--------------------------
I came across the similar problem again on another machine, but this time above solution doesn&#39;t work.
After some trying, I found restarting all the oracle related services can fix the problem. Originally when the installation is done, connection can be made. Somehow after several reboot of computer, there is problem.
I change all the oracle services with start time as auto. And once I could not connect, I restart them all over again (the core service should be restarted at last order), and works fine.

Some article says it might be due to the MTS problem. Microsoft&#39;s problem. Maybe!

I had the same Problem. I had start my Oracle TNS Listener, then it works normally again.

See [LISTENER: TNS-12545 ... No such file or directory](https://community.oracle.com/thread/2296782).

In your case the &quot;Vendor code 17002&quot; is the equivalent of the ORA-12541 error:  It&#39;s most likely that your listener is down, or has an improper port or service name.  From the docs:

    ORA-12541: TNS no listener

Cause: Listener for the source repository has not been started.

Action: Start the Listener on the machine where the source repository resides.

I am following the ruby.railstutorial. I run the command &quot;git push heroku master&quot; and it spits out this error.

    Permission denied (publickey).
    fatal: Could not read from remote repository.
    Please make sure you have the correct access rights
    and the repository exists.

I am inside my rails app &quot;/Users/lexi87/rails_projects/first_app&quot;. Any solutions?

git push heroku master permission denied

I have a sqlite  DB with a table with the following structure LocationName  Latitude Longitude all defined as varchar. How i can construct a sql statement to get all the locations with a specific lat range given latitude in decimal. is there a way to do that convert from varchar to decimal value on the fly ? or i have to step through the return statements  and do the conversion manually 


Convert Text to Numbers in SQLite

I&#39;m trying to connect to a database using SQLDeveloper and I get the following error:

    An Error was Encountered performing The requested operation:
    
    IO Error: Conection reset
    
    Vendor code 17002.

Could you please help me?

Vendor code 17002 to connect to SQLDeveloper

I'm trying to connect to a database using SQLDeveloper and I get the following error:
<pre><code class="hljs language-javascript">An Error was Encountered performing The requested operation:

IO Error: Conection reset

Vendor code 17002.
</code></pre>
Could you please help me?

I have more than 50 databases hosted in my postgresql server. I need to move some of them on another host, to free-up some disk space,but how can I measure the disk-space used by each database on my volume?

Is there any function exists to get the information that I want?

Postgresql find total disk space used by a database

I have an application developed using the MVC pattern and I would like to index now multiple models of it, this means each model has a different data structure.

*  Is it better to use mutliple indexes, one for each model or have a type within the same index for each model? Both ways would also require a different search query I think. I just started on this.

* Are there differences performancewise between both concepts if the data set is small or huge?

I would test the 2nd question myself if somebody could recommend me some good sample data for that purpose.

Elastic search, multiple indexes vs one index and types for different data sets?

We have a table of photos with the following columns: 

    id, merchant_id, url 

this table contains duplicate values for the combination `merchant_id, url`. so it&#39;s possible that one row appears more several times. 

    234 some_merchant  http://www.some-image-url.com/abscde1213
    235 some_merchant  http://www.some-image-url.com/abscde1213
    236 some_merchant  http://www.some-image-url.com/abscde1213



What is the best way to delete those duplications?
(I use PostgreSQL 9.2 and Rails 3.)


Find duplicate rows with PostgreSQL

If we had a table like this:

Books (pretend &quot;ISBN&quot; doesn&#39;t exist)


 - Author
 - Title
 - Edition
 - Year of publication
 - Price

One could argue that {Author,Title,Edition} could be a candidate/primary key. 

What determines whether the candidate/primary key should be {Author,Title,Edition} or whether an ID column should be used, with {Author,Title,Edition} a unique index/key constraint?

So is

 - Author (PK)
 - Title (PK)
 - Edition (PK)
 - Year of publication
 - Price

better, or:

 - ID (PK)
 - Author
 - Title
 - Edition
 - Year of publication
 - Price

where {Author,Title,Edition} is an additional unique index/constraint?

Composite Primary key vs additional &quot;ID&quot; column?

I would like to know how much space does my MySQL database use, in order to select a web host.
I found the command `SHOW TABLE STATUS LIKE &#39;table_name&#39;` so when I do the query, I get something like this:

    Name       | Rows | Avg. Row Length | Data_Length | Index Length
    ----------   ----   ---------------   -----------   ------------
    table_name   400          55            362000        66560

* numbers are rounded.

So do I have **362000**  or 400*362000 = **144800000** bytes of data for this table?
And what does Index Length mean?
Thanks !

How to Get True Size of MySQL Database?

**Scenario**: Consider the following is the part of code from a node web app.

    app.get(&#39;/users/:id?&#39;, function(req, res, next){
        var id = req.params.id;
        if (id) {
            // do something
        } else {
            next(); //or return next();
        }
    });

**Issue**: I am checking which one to go with just `next()` or `return next()`. Above sample code works exactly the same for both &amp; did not show any difference in execution. 

**Question**: Can some one put light on this, when to use `next()` and when to use `return next()` and some important difference?

When to use next() and return next() in Node.js

I am developing one app, and what I think I wanna do is receive data from server database in android. So I started to run some tutorials. I found one that is doing pretty much what I want. 
But I am getting: 

    detailMessage	&quot;failed to connect to localhost/127.0.0.1 (port 8080): connect failed: ECONNREFUSED (Connection refused)&quot; (id=830021648792)	

Whole code of this tutorial is here [link][1]

Error occurs on : 

`OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream());`


  [1]: http://veereshr.com/Android/AndroidToServlet

I checked that:

 - firewall is disabled
 - ping is working
 - connection string is exactly the same as when I run the servlet from server admin interface - `http://localhost:8080/Requestor/RQSRV`
-the servlet is running 

My configuration :


 - Server : Glass Fish 4.0
 - Android App - Developed in Eclipse
 - Servlet - Developed in NetBeans



connect failed: ECONNREFUSED

I&#39;m a node.js developer who creates web apps using express.js.
By now, my problem is:

Whenever I create an app on my computer, npm install its stuff and run it (with node app.js and nodemon) I get this message in the console:

    connect.multipart() will be removed in connect 3.0
    visit https://github.com/senchalabs/connect/wiki/Connect-3.0 for alternatives
    connect.limit() will be removed in connect 3.0
    Express server listening on port 3000

The app works, that&#39;s fine. But when I clone an app created in other computer I don&#39;t get that message, so I&#39;m supposing I have something outdated in my computer.

I went to the site mentioned in the message and confirmed my speculations. That is a deprecation warning. However, I&#39;ve updated node and npm and globally express but I still getting the note. 

My problem is, therefore: I don&#39;t know what do I need to update in order to get rid of the deprecation notes because they&#39;re freaking me out. 

I hope someone can help me. 
Thanks a lot. 

How to get rid of Connect 3.0 deprecation alert?

I am new with ```Express```. As ```Express 4.x``` has removed bundled middlewares.
Any middleware I want to use should be required. When I read the README with [express-session][1] and [cookie-session][2] on github, I feel it hard to understand the difference.

So I try to write simple code to figure it out. I run twice for each middleware.

    var express = require(&#39;express&#39;)
	  , cookieParser = require(&#39;cookie-parser&#39;)
	  , session = require(&#39;cookie-session&#39;)
	  , express_sess = require(&#39;express-session&#39;)
	  , app = express();

	app.use(cookieParser())
	app.use(session({ keys: [&#39;abc&#39;], name: &#39;user&#39; }));
	//app.use(express_sess({ secret: &#39;abc&#39;, key: &#39;user&#39;}));
	app.get(&#39;/&#39;, function (req, res, next) {
		res.end(JSON.stringify(req.cookies));
		console.log(req.session)
		console.log(req.cookies)
	});

	app.listen(3000);

For ```cookie-session```, I always get {} in my terminal.

For ```express-session```, I get things like this.

    req.session: { cookie: { 
         path: &#39;/&#39;,
         _expires: null,
         originalMaxAge: null,
         httpOnly: true 
       } 
    }

    req.cookie: {user: &#39;s:aJ97vKA5CCwxqdTj0AV1siRQ.fWusS5+qfCKICtwkfrzcZ/Gq8P0Qdx/kx8mTBhoOhGU&#39;}

It really confuses me. So how to explain the result with the basic use? And what&#39;s the difference between them? When should I use them? 



  [1]: https://github.com/expressjs/session
  [2]: https://github.com/expressjs/cookie-session

What&#39;s difference with express-session and cookie-session?

NOTE: I have tried other solution given [here][1] but it didn&#39;t work

A newbie with NodeJs. I am trying to follow AngularJS pro and got stuck with setting up NodeJs server. According to book, I installed nodejs and then installed connect package using
npm install connect

then downloaded angularjs in folder next to nodejs folder. Then wrote server.js file to connect to server. Here is the content of the file:

        var connect = require(&#39;connect&#39;);
    connect.createServer(connect.static(&quot;../angularjs&quot;)).listen( 5000);


  When I run this server.js file using: 

    node server.js

I get following error:

     function app(req, res, next){ app.handle(req, res, next); }
     merge(app, proto);
     merge(app, EventEmitter.prototype);
     app.route = &#39;/&#39;;
     app.stack = [];
     return app;
     has no method &#39;static&#39;
       at Object.&lt;anonymous&gt; (C:\web\nodejs\server.js:2:36)
       at Module._compile (module.js:456:26)
       at Object.Module._extensions..js (module.js:474:10)
       at Module.load (module.js:356:32)
       at Function.Module._load (module.js:312:12)
       at Function.Module.runMain (module.js:497:10)
       at startup (node.js:119:16)
       at node.js:906:3
    
    
  [1]: https://stackoverflow.com/questions/23978734/node-connect-issue-object-function-createserver-has-no-method-static

Any ideas guys?
Thanks.


nodejs connect cannot find static

I have few SQL queries which has very low query running performance and I want to check the query execution plan for this query. I am trying to execute the below query but its not showing any query execution plan. Its only display message plan FOR succeeded. I dont know is there any settings that we have to do in oracle sql developer to vies explain plan for query :

    EXPLAIN PLAN FOR 
    Select SO.P_OPTION_ID FROM
    SIMSIM 
       JOIN P_TYPE PT on PT.KEY=SIM.P_TYPE_KEY JOIN P_CONFIG PC ON PC.ID=PT.PRODUCT_CONFIG_ID
    JOIN P_OPTION PO ON PO.OPTION_KEY=PC.DEFAULT_PRODUCT_OPTIONS JOIN S_OPTION SO ON SO.SERVICE_ID=SIM.ASSIGNED_TO_SERVICE_ID
    JOIN AVV_NO AN ON SIM.ASSIGNED_ANUMBER_ID = AN.ID
     where SO.STATUS_ID IN (20,40) 
     and SO.ID &lt; to_char(SYSDATE - numtodsinterval (  1,&#39;MINUTE&#39; ), &#39;YYYYMMDDHH24MISS&#39;)||&#39;0000&#39;
     and SO.ID &gt; to_char(SYSDATE - numtodsinterval (  1, &#39;HOUR&#39; ), &#39;YYYYMMDDHH24MISS&#39;)||&#39;0000&#39;
    and NOT EXISTS(SELECT ID from TEMP_BPL T WHERE T.ID = SO.ID );

How do I view the Explain Plan in Oracle Sql developer?

I have exported database from Oracle SQL developer tool into .sql file. Now I want to run this file which is of size 500+ MB.

I read about running scripts [here][1], but I didn&#39;t understand the way. Is there any command or query by which we can run this sql script by providing path?


  [1]: https://stackoverflow.com/questions/13137258/oracle-sql-developer-how-to-dynamicly-run-sql-scripts

How to run .sql file in Oracle SQL developer tool to import database?

I created the table Test_Project2 in Oracle SQL Developer. After that I realized that the column proj_name is of a small size, so I decided to modify the column using the follwoing statement

	ALTER TABLE TEST_PROJECT2 MODIFY proj_name VARCHAR2(300);
	
but for some reason Oracle SQL Developer underscores the semi-colon with red and I do not what is mistake and how to correct it

**Test_Project2**:

	CREATE TABLE Test_Project2 (
	proj_id number(30),
	proj_name VARCHAR2 (30),
	proj_desc VARCHAR2(300)
	);

how to modify the size of a column

I downloaded Windows 64-bit with JDK 8 included of SQL Developer 18.1.

To run Oracle SQL Developed I just unzipped the file and run the sqldeveloper.exe contained in the folder.

Unfortunately, as you can see in the image the size of everything is extremely small and very difficult to see.[![enter image description here][1]][1]

This issue appears exclusively with this software.

How can I resolve it? 

  [1]: https://i.stack.imgur.com/g3Znw.png

Content Type	Original Author	Original Content on Stackoverflow
Question	Gutenberg	View Question on Stackoverflow
Solution 1 - Database	Wajid Hussain Siddiqi	View Answer on Stackoverflow
Solution 2 - Database	luckyfish	View Answer on Stackoverflow
Solution 3 - Database	user3766355	View Answer on Stackoverflow
Solution 4 - Database	Punith Raj	View Answer on Stackoverflow

Vendor code 17002 to connect to SQLDeveloper

Database Problem Overview

Database Solutions

Solution 1 - Database

Solution 2 - Database

Solution 3 - Database

Solution 4 - Database

Convert Text to Numbers in SQLite

git push heroku master permission denied

Attributions