You need to right-click in the table designer and pick `Indexes/Keys`:

![enter image description here][1]

Then a dialog pops up and you can add a new index to the list of indices (on the left hand side) and define it to be a `unique` index:

![enter image description here][2]


  [1]: http://i.stack.imgur.com/dWQfa.png
  [2]: http://i.stack.imgur.com/UWX0r.png

Do right-click in the table designer and choose **Indexes/Keys**.

![enter image description here][1]

Indexes/Keys window will open. Click the button **Add**, to create the new index/key, and choose the column to be unique in the **Columns** property:

![enter image description here][2]

In the properties of the new index/key, set **Type** to **Unique Key**:

![enter image description here][3]

And this is the generated code for the unique constraint:

    ALTER TABLE [dbo].[Table_1] ADD  CONSTRAINT [IX_Table_1] UNIQUE NONCLUSTERED 
    (
        [myUniqueColumn] ASC
    )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
    GO


  [1]: http://i.stack.imgur.com/GbzzX.png
  [2]: http://i.stack.imgur.com/JRC2o.png
  [3]: http://i.stack.imgur.com/CHDKC.png

Try right clicking and choosing `Indexes/Keys`, adding a new index and setting `Is Unique` to Yes.

You just Right Click from which column you need to add unique key from your table and you can select the `Indexes/Keys`. Then you can add or delete the column which you want to set unique key

I&#39;ve started using transitions to &quot;modernise&quot; the feel of a site. So far, `:hover` transitions are working great. Now I&#39;m wondering if it&#39;s possible to trigger a transition based on other things, such as when a class changes.

Here&#39;s the relevant CSS:

    #myelem {
        opacity: 0;
        display: none;
        transition: opacity 0.4s ease-in, display 0.4s step-end;
        -ms-transition: opacity 0.4s ease-in, display 0.4s step-end;
        -moz-transition: opacity 0.4s ease-in, display 0.4s step-end;
        -webkit-transition: opacity 0.4s ease-in, display 0.4s step-end;
    }
    #myelem.show {
        display: block;
        opacity: 1;
        transition: opacity 0.4s ease-out, display 0.4s step-start;
        -ms-transition: opacity 0.4s ease-out, display 0.4s step-start;
        -moz-transition: opacity 0.4s ease-out, display 0.4s step-start;
        -webkit-transition: opacity 0.4s ease-out, display 0.4s step-start;
    }

The JavaScript to trigger the change is:

    document.getElementById(&#39;myelem&#39;).className = &quot;show&quot;;

But the transition doesn&#39;t seem to be happening - it&#39;s just jumping from one state to the other.

What am I doing wrong?

CSS transition from `display: none` on class change?

I have the following in code in my `onClick()` method as 

     List&lt;Question&gt; mQuestionsList = QuestionBank.getQuestions();
 
Now I have the intent after this line, as follows :

      Intent resultIntent = new Intent(this, ResultActivity.class);
      resultIntent.putParcelableArrayListExtra(&quot;QuestionsExtra&quot;, (ArrayList&lt;? extends Parcelable&gt;) mQuestionsList);
      startActivity(resultIntent);

I don&#39;t know how to pass this question lists in the intent from one activity to another activity
My Question class

    public class Question {
        private int[] operands;
        private int[] choices;
        private int userAnswerIndex;
    
        public Question(int[] operands, int[] choices) {
            this.operands = operands;
            this.choices = choices;
            this.userAnswerIndex = -1;
        }
    
        public int[] getChoices() {
            return choices;
        }
    
        public void setChoices(int[] choices) {
            this.choices = choices;
        }
    
        public int[] getOperands() {
            return operands;
        }
    
        public void setOperands(int[] operands) {
            this.operands = operands;
        }
    
        public int getUserAnswerIndex() {
            return userAnswerIndex;
        }
    
        public void setUserAnswerIndex(int userAnswerIndex) {
            this.userAnswerIndex = userAnswerIndex;
        }
    
        public int getAnswer() {
            int answer = 0;
            for (int operand : operands) {
                answer += operand;
            }
            return answer;
        }
    
        public boolean isCorrect() {
            return getAnswer() == choices[this.userAnswerIndex];
        }
    
        public boolean hasAnswered() {
            return userAnswerIndex != -1;
        }
    
        @Override
        public String toString() {
            StringBuilder builder = new StringBuilder();
    
            // Question
            builder.append(&quot;Question: &quot;);
            for(int operand : operands) {
                builder.append(String.format(&quot;%d &quot;, operand));
            }
            builder.append(System.getProperty(&quot;line.separator&quot;));
    
            // Choices
            int answer = getAnswer();
            for (int choice : choices) {
                if (choice == answer) {
                    builder.append(String.format(&quot;%d (A) &quot;, choice));
                } else {
                    builder.append(String.format(&quot;%d &quot;, choice));
                }
            }
            return builder.toString();
           }
        
          }



How to pass ArrayList of Objects from one to another activity using Intent in android?

I have an existing table with data. I have just added a new column but I cannot find how to add a unique constraint on that column. Could someone please advise? Right-clicking and selecting &quot;check constraints&quot; wasn&#39;t helpful.

Add unique constraint in SQL Server 2008 GUI?

<p>I have an existing table with data. I have just added a new column but I cannot find how to add a unique constraint on that column. Could someone please advise? Right-clicking and selecting "check constraints" wasn't helpful.</p>


I&#39;m trying to achieve a &quot;One to one&quot; relationship in a MySQL database. For example, let&#39;s say I have a Users table and an Accounts table. I want to be sure that a User can have only one Account. And that there can be only one Account per User.

I found two solutions for this but don&#39;t know what to use, and are there any other options.

### First solution:

    DROP DATABASE IF EXISTS test;
    CREATE DATABASE test CHARSET = utf8 COLLATE = utf8_general_ci;
    USE test;
    
    CREATE TABLE users(
    	id INT NOT NULL AUTO_INCREMENT,
    	user_name VARCHAR(45) NOT NULL,
    	PRIMARY KEY(id)
    ) ENGINE = InnoDB DEFAULT CHARSET = utf8;
    
    CREATE TABLE accounts(
    	id INT NOT NULL AUTO_INCREMENT,
    	account_name VARCHAR(45) NOT NULL,
    	user_id INT UNIQUE,
    	PRIMARY KEY(id),
    	FOREIGN KEY(user_id) REFERENCES users(id)
    ) ENGINE = InnoDB DEFAULT CHARSET = utf8;

In this example, I define the foreign key in accounts pointing to the primary key in users.
And then I make foreign key UNIQUE, so there can&#39;t be two identical users in accounts.
To join tables I would use this query:

    SELECT * FROM users JOIN accounts ON users.id = accounts.user_id;

### Second solution:

    DROP DATABASE IF EXISTS test;
    CREATE DATABASE test CHARSET = utf8 COLLATE = utf8_general_ci;
    USE test;
    
    CREATE TABLE users(
    	id INT NOT NULL AUTO_INCREMENT,
    	user_name VARCHAR(45) NOT NULL,
    	PRIMARY KEY(id)
    ) ENGINE = InnoDB DEFAULT CHARSET = utf8;
    
    CREATE TABLE accounts(
    	id INT NOT NULL AUTO_INCREMENT,
    	account_name VARCHAR(45) NOT NULL,
    	PRIMARY KEY(id),
    	FOREIGN KEY(id) REFERENCES users(id)
    ) ENGINE = InnoDB DEFAULT CHARSET = utf8;

In this example, I create a foreign key that points from the primary key to a primary key in another table. Since Primary Keys are UNIQUE by default, this makes this relation One to One.
To join tables I can use this:

    SELECT * FROM users JOIN accounts ON users.id = accounts.id;

Now the questions:

 - What is the best way to create One to One relation in MySQL?
 - Are there any other solutions other than these two?

I&#39;m using MySQL Workbench, and when I design One To One relation in EER diagram and let MySQL Workbench produce SQL code, I get One to Many relation :S That&#39;s what&#39;s confusing me :S

And if I import any of these solutions into MySQL Workbench EER diagram, it recognizes relations as One to Many :S That&#39;s also confusing.

So, what would be the best way to define One to One relation in MySQL DDL. And what options are there to achieve this?


MySQL - One To One Relationship?

I have simple question:

I have a **`postgresql`** table: `Scores(score integer)`.

How would I get the highest 10 scores the fastest?  

**UPDATE:** 

I will be doing this query multiple times and am aiming for the fastest solution.

How to get the top 10 values in postgresql?

&gt; **Possible Duplicate:**  
&gt; [MySQL ON vs USING?](https://stackoverflow.com/questions/11366006/mysql-on-vs-using)  

&lt;!-- End of automatically inserted text --&gt;

Query 1:

    SELECT *
    FROM users
    JOIN orders ON (orders.user_id = users.user_id)
    WHERE users.user_id = 1;

Query 2:

    SELECT *
    FROM users
    JOIN orders USING (user_id)
    WHERE user_id = 1;

I want to join orders and users tables to get some certain data. It works fine. My issue is since both queries output the same results set, is it the same? Which one is more efficient to be used? Which one is good for performance ? Which one is the best practise ? 



USING Keyword vs ON clause - MYSQL

I just read part of an optimization article and *segfaulted* on the following statement:

&gt; When using SQL replace statements using `OR` with a `UNION`:

&gt;     select username from users where company = ‘bbc’ or company = ‘itv’;

&gt; to:
 
&gt;     select username from users where company = ‘bbc’ union
    select username from users where company = ‘itv’;

From a quick `EXPLAIN`:

Using `OR`:

![enter image description here][1]

Using `UNION`:

![enter image description here][2]

Doesn&#39;t this mean `UNION` does in *double the work*?

While I appreciate `UNION` may be more performant for certain RDBMSes and certain table schemas, this is not *categorically true* as the author suggestions.

### Question
Am I wrong?


  [1]: http://i.stack.imgur.com/sxoLS.png
  [2]: http://i.stack.imgur.com/HAqu6.png

SQL Performance UNION vs OR

I see many similar questions but they&#39;re either so complex I can&#39;t understand them, or they don&#39;t seem to be asking the same thing.

It&#39;s simple: I have two columns: users (dmid) and downloads (dfid).

1. Select all users who downloaded a specific file:

        SELECT DISTINCT dmid FROM downloads_downloads where dfid = &quot;7024&quot;

2. Using the users above, find all the files they all downloaded:

        SELECT dfid from downloads_downloads WHERE dmid = {user ids from #1 above}

3. Count and order the dfid results , so we can see how many downloads each file received:

        dfid    dl_count_field
        ----    --------------
        18       103
        3        77
        903      66

 
**My attempt at answering.**

This seems close, but MySql bogs down and doesn&#39;t respond even after 30 seconds--I restart Apache eventually. And I do not now how to structure the count and order by without getting syntax errors because of the complex statement--and it may not even be the right statement.

    SELECT dfid from downloads_downloads WHERE dmid IN (
        SELECT DISTINCT dmid FROM `downloads_downloads` where dfid = &quot;7024&quot;)


Use results from one sql query in another where statement (subquery?)

I want to update my column CODE_DEST with an incremental number.  I have:

    CODE_DEST   RS_NOM
    null        qsdf
    null        sdfqsdfqsdf
    null        qsdfqsdf

I would like to update it to be:

    CODE_DEST   RS_NOM
    1           qsdf
    2           sdfqsdfqsdf
    3           qsdfqsdf

I have tried this code:

    UPDATE DESTINATAIRE_TEMP
    SET CODE_DEST = TheId 
    FROM (SELECT  Row_Number()   OVER (ORDER BY [RS_NOM]) AS TheId FROM DESTINATAIRE_TEMP)

This does not work because of the `)`

I have also tried:

    WITH DESTINATAIRE_TEMP AS
      (
        SELECT 
        ROW_NUMBER() OVER (ORDER BY [RS_NOM] DESC) AS RN
        FROM DESTINATAIRE_TEMP
      )
    UPDATE DESTINATAIRE_TEMP SET CODE_DEST=RN

But this also does not work because of union.

How can I update a column using the `ROW_NUMBER()` function in SQL Server 2008 R2?

SQL Update with row_number()

I am creating a project in which I need to run 2-3 SQL commands in a single SQL connection.
Here is the code I have written: 

    SqlConnection con = new SqlConnection(@&quot;Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\project.mdf;Integrated Security=True&quot;);
    con.Open();
    SqlCommand cmd = new SqlCommand(&quot;select *  from &quot; + mytags.Text + &quot; &quot;, con);
    SqlDataReader rd = cmd.ExecuteReader();
    if (rd.Read())
    {
        con.Close();
        con.Open();
        SqlCommand cmd1 = new SqlCommand(&quot;insert into &quot; + mytags.Text + &quot; values (&#39;fname.lname@gmail.com&#39;,&#39;&quot; + TextBox3.Text + &quot;&#39;,&#39;&quot; + TextBox4.Text + &quot;&#39;,&#39;&quot; + TextBox5.Text + &quot;&#39;,&#39;&quot;+mytags.Text+&quot;&#39;)&quot;, con);
        cmd1.ExecuteNonQuery();
        label.Visible = true;
        label.Text = &quot;Date read and inserted&quot;;
    }
    else
    {
        con.Close();
        con.Open();
        SqlCommand cmd2 = new SqlCommand(&quot;create table &quot; + mytags.Text + &quot; ( session VARCHAR(MAX) , Price int , Description VARCHAR(MAX), Date VARCHAR(20),tag VARCHAR(10))&quot;, con);
        cmd2.ExecuteNonQuery();
        con.Close();
        con.Open();
        SqlCommand cmd3 = new SqlCommand(&quot;insert into &quot; + mytags.Text + &quot; values (&#39;&quot; + Session + &quot;&#39;,&#39;&quot; + TextBox3.Text + &quot;&#39;,&#39;&quot; + TextBox4.Text + &quot;&#39;,&#39;&quot; + TextBox5.Text + &quot;&#39;,&#39;&quot; + mytags.Text + &quot;&#39;)&quot;, con);
        cmd3.ExecuteNonQuery();
        label.Visible = true;
        label.Text = &quot;tabel created&quot;;
        con.Close();
    }
            
I have tried to remove the error and I got that the connection is not going to else condition. Please review the code and suggest if there is any mistake or any other solution for this.

How to run multiple SQL commands in a single SQL connection?

I have to insert about 2 million rows from a text file.

And with inserting I have to create some master tables. 

What is the best and fast way to insert such a large set of data into SQL Server?



Insert 2 million rows into SQL Server quickly

I need help from you, this is my sql query:

    select count(SID) 
    from Test 
    where Date = &#39;2012-12-10&#39; 
    group by SID

this is my result:

    |2|
    |3|
    |4|
    |3|

and now I have to count the results from first query! 

    Expected result: 4 



Select count(*) from result query

I have used the following namespace to connect my project to the sql server:

    using System.Configuration;

and also used 

    string str=System.Configuration.ConfigurationSettings.AppSettings[&quot;myconnection&quot;];
    SqlConnection oconnection = new SqlConnection(str);
    oconnection.Open();

when I run the program ,an error has been occurred and show the message 

&gt; &#39;System.Configuration.ConfigurationSettings.AppSettings&#39; is
&gt; obsolete.This method is obsolete,it has been replaced by
&gt; &#39;System.Configuration!
&gt; System.Configuration.ConfigurationManager.AppSettings &#39;

 but I have no found ConfigurationManager in that namespace and for `oconnection.Open();` the message is 

&gt; InvalidOperationException

was unhandled.

What can I do?

configurationManager does not exist in the namespace System.Configuration

I have a query that is returning the exchange rate value set up in our system. Not every order will have an exchange rate (currate.currentrate) so it is returning null values. 

Can I get it to return 1 instead of null?

Something like an if statement maybe:

     if isnull(currate.currentrate) then 1 else currate.currentrate 

Here is my query below.  I greatly appreciate all your help!

     SELECT     orderhed.ordernum, orderhed.orderdate, currrate.currencycode,  currrate.currentrate
     FROM         orderhed LEFT OUTER JOIN
                      currrate ON orderhed.company = currrate.company AND orderhed.orderdate = currrate.effectivedate

SQL query, if value is null then return 1

How to recover the unsaved scripts if the SSMS crashes / unsaved tab gets accidentally closed?

Recover unsaved SQL query scripts

I installed Microsoft SQL Server 2008.

When I start SQL Server Management Studio (SSMS), I get the `Connect to Server` login window with a blank textbox for `Server name`. I have tried a lot of names, but I couldn&#39;t solve it.

How can I find / get the server name?  

How to find server name of SQL Server Management Studio

I just upgraded from SSMS 2005 to 2012.  Previously, I could hit &lt;kbd&gt;CTRL&lt;/kbd&gt;+&lt;kbd&gt;R&lt;/kbd&gt; and the Query Results windows would disappear.

After I upgraded to SSMS I ran a query and, out of habit, hit &lt;kbd&gt;CTRL&lt;/kbd&gt;+&lt;kbd&gt;R&lt;/kbd&gt;.  Nothing happened.  At the bottom of SSMS I noticed that the status bar was reporting &quot;(Ctrl+R) was pressed.  Waiting for the second key of chord...&quot;

After checking out the details of this keyboard shortcut in the [MSDN documentation][1], I found out that &lt;kbd&gt;CTRL&lt;/kbd&gt;+&lt;kbd&gt;R&lt;/kbd&gt; was suppose to hide the resulting window as I had suspected.  However, my SSMS isn&#39;t behaving as documented.

Is there a way that I can restore this keyboard shortcut to hide my Query Result window?


  [1]: http://msdn.microsoft.com/en-us/library/ms174205.aspx

CTRL+R does not hide the Query Result window in SSMS

I&#39;m following [Code First to an Existing Database](http://msdn.microsoft.com/en-us/data/jj200620) tutorial and noticed that it suggested to connect to `(localdb)\v11.0` in learning purposes. I&#39;ve tried to connect to it using my SQL Management Studio and it worked. But when I&#39;ve restored a DB backup it created an `[DatabaseName].mdf` file in my user&#39;s directory.

I&#39;m quite surprised and have following questions:

 1. What is a `(localdb)\v11.0`? Does it uses my SQL Express or SQL Compact?
 2. Does it support only databases stored in `.mdf` files?
 3. How can I specify path for my restore other than my user&#39;s folder?
 4. What general purposes does it serve (is it for learning purposes only)?
 5. Where can I find more info about this kind of database?

 

SQL Server (localdb)\v11.0 explained

I am getting the following error

    Cannot execute as the database principal because the principal &quot;dbo&quot; 
    does not exist, this type of principal cannot be impersonated,
    or you do not have permission.

I read about `ALTER AUTHORIZATION`, but I have no idea what database this is happening in. This error is getting spit out very frequently, and grows the error log by about 1GB every day. 

SQL Server principal &quot;dbo&quot; does not exist,

I need to drop the primary key of a table `Student` in a SQL Server database.

I have edited in the table and the script I got is
  
    ALTER TABLE dbo.Student
    	DROP CONSTRAINT PK__Student__9CC368536561EF8B

But when I run this script in SQL Server query browser to drop the primary key

It shows the message

&gt; *Msg 3728, Level 16, State 1, Line 1  
&gt; &#39;PK\_\_Student\_\_9CC368536561EF8B&#39; is not a constraint.  
&gt; Msg 3727, Level 16, State 0, Line 1*

To my concern I think `PK__Student__9CC368536561EF8B` this will be generated randomly
please help me to drop the primary key constraint using **script**.

Thanks in advance


Drop primary key using script in SQL Server database

My code is like shown below :

    select col1,count(col2) as col7
    from --some join operation
    group by col1
    having col7 &gt;= 3 -- replace col7 by count(col2) to make the code work

My code causes the error &quot;Invalid column name &#39;col7&#39; &quot;. Why does this happen ? It seems illogical that SQL does not allow me to use col7 in the last line. 

I am using SQL server express 2008 

Why can&#39;t I use an alias for an aggregate in a having clause?

While I am searching through my database, I run an INSERT statement if I find that a particular item does not exist, and I run a different INSERT statement if I find one or more of this item.

I am not entirely sure how to use the IF ELSE expressions.

What I have so far is a statement that will count the number of times the target data appears; it will print TRUE if it is greater than 0, if not, it will print FALSE. I can&#39;t find any examples to help me understand how I can use this to run two different INSERT statements.

Here is what I have so far:

    SELECT CASE WHEN COUNT(*)&gt;0 THEN &#39;TRUE&#39; ELSE &#39;FALSE&#39; END
    (
      SELECT [Some Column], COUNT(*) TotalCount
      FROM INCIDENTS
      WHERE [Some Column] = &#39;Target Data&#39;
      GROUP BY [Some Column]
    )

Using IF ELSE statement based on Count to execute different Insert statements

Could you help me frame a query that retrieves the constraints in all the tables, the count of constraints in each table, and also display `NULL` for tables that do NOT have any constraints.

This is what I have so far:

    Select  SysObjects.[Name] As [Constraint Name] ,
    		Tab.[Name] as [Table Name],
    		Col.[Name] As [Column Name]
    From SysObjects Inner Join 
    (Select [Name],[ID] From SysObjects) As Tab
    On Tab.[ID] = Sysobjects.[Parent_Obj] 
    Inner Join sysconstraints On sysconstraints.Constid = Sysobjects.[ID] 
    Inner Join SysColumns Col On Col.[ColID] = sysconstraints.[ColID] And Col.[ID] = Tab.[ID]
    order by [Tab].[Name] 

Content Type	Original Author	Original Content on Stackoverflow
Question	mezamorphic	View Question on Stackoverflow
Solution 1 - Sql	marc_s	View Answer on Stackoverflow
Solution 2 - Sql	Guillermo Gutiérrez	View Answer on Stackoverflow
Solution 3 - Sql	podiluska	View Answer on Stackoverflow
Solution 4 - Sql	dinesh.k	View Answer on Stackoverflow

Add unique constraint in SQL Server 2008 GUI?

Sql Problem Overview

Sql Solutions

Solution 1 - Sql

Solution 2 - Sql

Solution 3 - Sql

Solution 4 - Sql

How to pass ArrayList of Objects from one to another activity using Intent in android?

CSS transition from `display: none` on class change?

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