Try this :

    select if(Id is null, 0, id) as Id;

[The documentation][1] is your friend; you should read it!

It says:

&gt;     IFNULL(expr1,expr2)
&gt; 
&gt; If `expr1` is not `NULL`, `IFNULL()` returns `expr1`; otherwise it returns
&gt; `expr2`.

And then lots of examples. This is equivalent to using a ternary conditional with a comparison to `NULL` and the comparison subject as the second operand; that it doesn&#39;t happen to use the symbols `?` and `:` to get you there is not really relevant to anything.

So, in your case:

    SELECT IFNULL(`id`, 0) FROM `table`

If you&#39;re desperate to provide three operands explicitly (why?!), then switch to `IF`:

    SELECT IF(`id` IS NULL, 0, `id`) FROM `table`

  [1]: http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html

There are two ways that you can implement the same logic as a ternary operator:

 1. Use the `IF` function, eg. `IF(expression, true result, false result)`
 2. Use the `CASE` expression, eg. 
      
        CASE WHEN expression THEN &lt;true result&gt; ELSE &lt;false_result&gt; END

When you are checking for NULL then you can use the `IFNULL` or `COALESCE` functions, eg.

    IFNULL(ID, 0)
    COALESCE(ID, 0)

`createuser` allows creation of a user (ROLE) in PostgreSQL. Is there a simple way to check if that user(name) exists already? Otherwise createuser returns with an error:

    createuser: creation of new role failed: ERROR:  role &quot;USR_NAME&quot; already exists

UPDATE: The solution should be executable from shell preferrably, so that it&#39;s easier to automate inside a script.

How to check if a postgres user exists?


I am trying to play an audio file when I click the button, but it&#39;s not working, my html code is:

    &lt;html&gt;    
        &lt;body&gt;
            &lt;div id=&quot;container&quot;&gt;
                &lt;button id=&quot;play&quot;&gt;
                    Play Music
                &lt;/button&gt;
            &lt;/div&gt;
        &lt;/body&gt;
    &lt;/html&gt;

my JavaScript is :

    $(&#39;document&#39;).ready(function () {
        $(&#39;#play&#39;).click(function () {
            var audio = {};
            audio[&quot;walk&quot;] = new Audio();
            audio[&quot;walk&quot;].src = &quot;http://www.rangde.org/static/bell-ring-01.mp3&quot;
            audio[&quot;walk&quot;].addEventListener(&#39;load&#39;, function () {
                audio[&quot;walk&quot;].play();
            });
        });
    });   

I have created a [Fiddle][1] for that too.


  [1]: http://jsfiddle.net/sureshpattu/gD4Dr/1/


Play an audio file using jQuery when a button is clicked

I want to implement ternary conditional operator in MySQL. I have a table in which one field id exist. Its value may be null. I want to display `id` in ternary conditional format like this:

    select id = id == null ? 0 : id;

Is it possible in MySQL?


How to implement ternary conditional operator in MySQL

I want to implement ternary conditional operator in MySQL. I have a table in which one field id exist. Its value may be null. I want to display <code>id</code> in ternary conditional format like this:
<pre><code class="hljs language-bash">select id = id == null ? 0 : id;
</code></pre>
Is it possible in MySQL?

In the table below, how do I get just the **most recent row** with `id=1` based on the `signin` column, and not all 3 rows?

    +----+---------------------+---------+
    | id | signin              | signout |
    +----+---------------------+---------+
    |  1 | 2011-12-12 09:27:24 | NULL    |
    |  1 | 2011-12-13 09:27:31 | NULL    |
    |  1 | 2011-12-14 09:27:34 | NULL    |
    |  2 | 2011-12-14 09:28:21 | NULL    |
    +----+---------------------+---------+

Get most recent row for given ID

I&#39;m trying to do this:

    SELECT CAST(columnName AS INT), moreColumns, etc
    FROM myTable
    WHERE ...

I&#39;ve looked at the help FAQs here: http://dev.mysql.com/doc/refman/5.0/en/cast-functions.html , it says I can do it like `CAST(val AS TYPE)`, but it&#39;s not working.

Trying to convert a decimal to int, real value is 223.00 and I want 223

CAST DECIMAL to INT

I am trying to setup a few simple SQL scripts to help with some short term DB administration.
As such, I&#39;m setting up variables to try to make it easier to reuse these scripts.

The problem I&#39;m having is specifically with the LIKE clause.

    SET @email = &#39;test@test.com&#39;;
    
    SELECT email from `user` WHERE email LIKE &#39;%@email%&#39;;

So I want to have it finding results based on the email SET in the variable.  The query works if I manually enter the email into the LIKE clause.

How can I get the LIKE clause to work with the user variable?

UPDATE:
@dems&#39;s answer works for this simple case, but I&#39;m having trouble with a more complex query.

    SET @email = &#39;test@test.com&#39;;

    SELECT project.projectno, project.projectname, login.username, 
    CONCAT(login.firstname, &#39; &#39;, login.lastname), projectuser.title 
    FROM projectuser 
    INNER JOIN login ON projectuser.uid = login.uid 
    LEFT JOIN project ON projectuser.pid = project.pid
    WHERE login.username LIKE CONCAT (&#39;%&#39;, @email, &#39;%&#39;)

Gives me the error &quot;FUNCTION mydb.CONCAT does not exist&quot;

The query works without the CONCAT():

    SET @email = &#39;test@test.com&#39;;
    
    SELECT project.projectno, project.projectname, login.username, 
    CONCAT(login.firstname, &#39; &#39;, login.lastname), projectuser.title 
    FROM projectuser 
    INNER JOIN login ON projectuser.uid = login.uid 
    LEFT JOIN project ON projectuser.pid = project.pid
    WHERE login.username LIKE @email

How to use an user variables in MySQL LIKE clause?

When I execute this command in MySQL:

    SET FOREIGN_KEY_CHECKS=0;

Does it affect the whole engine or it is only my current transaction?

Does MySQL foreign_key_checks affect the entire database?

Is there a way in a MySQL statement to order records (through a date stamp) by &gt;= NOW() -1 so all records from the day before today to the future are selected?

Select records from NOW() -1 Day

Why does the first return a reference?

	int x = 1;
	int y = 2;
	(x &gt; y ? x : y) = 100;

While the second does not?

	int x = 1;
	long y = 2;
	(x &gt; y ? x : y) = 100;

Actually, the second did not compile at all - &quot;not lvalue left of assignment&quot;.


Return type of &#39;?:&#39; (ternary conditional operator)

I know that in PHP 5.3 instead of using this redundant ternary operator syntax:

    startingNum = startingNum ? startingNum : 1

...we can use a shorthand syntax for our ternary operators where applicable:

    startingNum = startingNum ?: 1

And I know about the ternary operator in JavaScript:

    startingNum = startingNum ? startingNum : 1

...but is there a shorthand?




JavaScript shorthand ternary operator

Can we use `elif` in list comprehension?  

Example :  

    l = [1, 2, 3, 4, 5]

    for values in l:
        if values==1:
            print &#39;yes&#39;
        elif values==2:
            print &#39;no&#39;
        else:
            print &#39;idle&#39;

Can we include the `elif` in our list comprehension, in a similar fashion to the code above?

For example, an answer like:   

    [&#39;yes&#39;, &#39;no&#39;, &#39;idle&#39;, &#39;idle&#39;, &#39;idle&#39;]

Up until now, I have only used `if` and `else` in list comprehension.

`elif` in list comprehension conditionals

How can I use an inline `if` statement in JavaScript? Is there an inline `else` statement too?

Something like this:

    var a = 2;
    var b = 3;
    
    if(a &lt; b) {
        // do something
    }

How to write an inline IF statement in JavaScript?

Two questions about using a question mark &quot;?&quot; and colon &quot;:&quot; operator within the parentheses of a print function:  What do they do? Also, does anyone know the standard term for them or where I can find more information on their use?  I&#39;ve read that they are similar to an &#39;if&#39; &#39;else&#39; statement.

    int row = 10;
    int column;
    while (row &gt;= 1)
	{
		column = 1;
		while(column &lt;= 10)
		{
			System.out.print(row % 2 == 1 ? &quot;&lt;&quot; : &quot;\r&gt;&quot;);
			++column;
		}
		--row;
		System.out.println();
	}

Content Type	Original Author	Original Content on Stackoverflow
Question	user1086355	View Question on Stackoverflow
Solution 1 - Mysql	Dewasish Mitruka	View Answer on Stackoverflow
Solution 2 - Mysql	Lightness Races in Orbit	View Answer on Stackoverflow
Solution 3 - Mysql	a'r	View Answer on Stackoverflow

How to implement ternary conditional operator in MySQL

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

Solution 3 - Mysql

Play an audio file using jQuery when a button is clicked

How to check if a postgres user exists?

Attributions