Since you want to add *hours*, it should rather be:

    SELECT date_field + interval &#39;1 hour&#39; * start_time

`start_time` can be any numerical value.  
`&#39;1 hour&#39;` can be shortened to `&#39;1h&#39;`.  
[`interval` can be multiplied by a scalar.][1]


  [1]: https://www.postgresql.org/docs/current/functions-datetime.html#OPERATORS-DATETIME-TABLE

Found the answer, [in another SO question](https://stackoverflow.com/questions/10909902/how-to-add-number-of-days-in-postgresql-datetime):

    date + interval &#39;1&#39; minute * FLOOR(start_time * 60)

Hope that helps anyone

The one worked for me is

    SELECT date_field + interval &#39;1&#39; HOUR * start_time

**start_time** can be any numerical value.

If anyone wants to add in time stamp then
~~~
select time &#39;05:00&#39; - interval &#39;2 hours&#39;	
~~~

I currently have migration called Products, and I simply want to add few more strings to this migration such as description and product type. What is the best way to do this? 

    class CreateProducts &lt; ActiveRecord::Migration
      def change
        create_table :products do |t|
          t.string  :name
          t.decimal :price
          t.text    :description
          t.timestamps
        end
       end
     end




Rails generate Migration

I am working with Mongo DB and I am a newbie to it. I am about to install it on a server specifically for Mongo.

I would like to create 2 instances of it - 1 to support a QA environment, the other to support a Staging Environment.

I am more familiar with SQL Server where I can create multiple instances.

Is it possible to do the same with Mongo DB and if so, how?

multiple instances of Mongo DB on same server

[Apparently][1], PostgreSQL doesn&#39;t have `DATEADD`, because you can just use the `+` or `-` operators.

I need to add a number of hours to a date, which is accomplished like this:

    date_field + interval &#39;8.25 hour&#39; 

Which is great, but I need the number of hours to come from a field in the table. Would be something like this:

    date_field + interval start_time &#39;hour&#39; 

I can&#39;t find anywhere how to do this. Is this actually impossible?

I don&#39;t mind resorting to ugly hacks like taking the field value and dividing by 3600, multiplying by 86400. Whatever I need to do, but I haven&#39;t found any way to do that either.


  [1]: http://wiki.postgresql.org/wiki/Working_with_Dates_and_Times_in_PostgreSQL

How to add a variable number of hours to a date in PostgreSQL?

<a href="http://wiki.postgresql.org/wiki/Working_with_Dates_and_Times_in_PostgreSQL" target="_blank" rel="noopener noreferrer">Apparently</a>, PostgreSQL doesn't have <code>DATEADD</code>, because you can just use the <code>+</code> or <code>-</code> operators.
I need to add a number of hours to a date, which is accomplished like this:
<pre><code class="hljs language-sql">date_field + interval '8.25 hour' 
</code></pre>
Which is great, but I need the number of hours to come from a field in the table. Would be something like this:
<pre><code class="hljs language-sql">date_field + interval start_time 'hour' 
</code></pre>
I can't find anywhere how to do this. Is this actually impossible?
I don't mind resorting to ugly hacks like taking the field value and dividing by 3600, multiplying by 86400. Whatever I need to do, but I haven't found any way to do that either.

I&#39;m trying to run a query of about 50,000 records using ActiveRecord&#39;s `find_each` method, but it seems to be ignoring my other parameters like so:

    Thing.active.order(&quot;created_at DESC&quot;).limit(50000).find_each {|t| puts t.id }

Instead of stopping at 50,000 I&#39;d like and sorting by `created_at`, here&#39;s the resulting query that gets executed over the *entire* dataset:

    Thing Load (198.8ms)  SELECT &quot;things&quot;.* FROM &quot;things&quot; WHERE &quot;things&quot;.&quot;active&quot; = &#39;t&#39; AND (&quot;things&quot;.&quot;id&quot; &gt; 373343) ORDER BY &quot;things&quot;.&quot;id&quot; ASC LIMIT 1000

Is there a way to get similar behavior to `find_each` but with a total max limit and respecting my sort criteria?

ActiveRecord find_each combined with limit and order

How can I quickly remove all rows in the table using Entity Framework?

I am currently using:

```c#
var rows = from o in dataDb.Table
		   select o;
foreach (var row in rows)
{
	dataDb.Table.Remove(row);
}
dataDb.SaveChanges();
```

However, it takes a long time to execute.

Are there any alternatives?


Entity Framework. Delete all rows in table

I have a .sql file with a bunch of insert commands that I want to execute on my postgres database on heroku. But I don&#39;t know how to do it:-

If I had access to postgres console I&#39;d type the following:

    psql -h localhost -d database -U username -f datafile.sql

but it seems that heroku doesn&#39;t support this command. I&#39;ve tried with

    heroku pg:psql

but that doesn&#39;t let me input a file.

Are there any other options?

how to execute a .sql script on heroku?

I am looking for help to import a `.csv` file into SQL Server using `BULK INSERT` and I have few basic questions.

**Issues:**  

1. The CSV file data may have `,` (comma) in between (Ex: description), so how can I  make import handling these data?  

2. If the client creates the CSV from Excel then the data that have comma are enclosed within `&quot;&quot;` (double quotes) [as the below example] so how do the import can handle this?  

3. How do we track if some rows have bad data, which import skips? (does import skips rows that are not importable)

Here is the sample CSV with header:

    Name,Class,Subject,ExamDate,Mark,Description
    Prabhat,4,Math,2/10/2013,25,Test data for prabhat.
    Murari,5,Science,2/11/2013,24,&quot;Test data for his&#39;s test, where we can test 2nd ROW, Test.&quot;
    sanjay,4,Science,,25,Test Only.

And SQL statement to import:

    BULK INSERT SchoolsTemp
    FROM &#39;C:\CSVData\Schools.csv&#39;
    WITH
    (
        FIRSTROW = 2,
        FIELDTERMINATOR = &#39;,&#39;,  --CSV field delimiter
        ROWTERMINATOR = &#39;\n&#39;,   --Use to shift the control to next row
        TABLOCK
    )

Import CSV file into SQL Server

I have a database table called &#39;**tbl_transaction**&#39; with the following definition:
    
    id INT(11) Primary Key
    action_type ENUM(&#39;Expense&#39;, &#39;Income&#39;)
    action_heading VARCHAR (255)
    action_amount FLOAT

I would like to generate two columns: `Income Amt` and `Expense Amt`.

Is it possible to populate the columns conditionally, using only a SQL Query, such that the output appears in the correct column, depending on whether it is an Expense item or an Income item?

For example:
    
    ID        Heading         Income Amt       Expense Amt
    1         ABC             1000             -
    2         XYZ             -                2000


I&#39;m using MySQL as the database. I&#39;m trying to use the CASE statement to accomplish this. 

Cheers!

Case statement in MySQL

Why psql can&#39;t find relation name for existing table?

I&#39;m a postgres novice. 

I installed the postgres.app for mac. I was playing around with the psql commands and I accidentally dropped the postgres database. I don&#39;t know what was in it. 

I&#39;m currently working on a tutorial: http://www.rosslaird.com/blog/building-a-project-with-mezzanine/

And I&#39;m stuck at `sudo -u postgres psql postgres`

ERROR MESSAGE: `psql: FATAL:  role &quot;postgres&quot; does not exist`

$ which psql 
     
    /Applications/Postgres.app/Contents/MacOS/bin/psql


This is what prints out of `psql -l`

	                                List of databases
	    Name    |   Owner    | Encoding | Collate | Ctype |     Access privileges     
	------------+------------+----------+---------+-------+---------------------------
	 user       | user       | UTF8     | en_US   | en_US | 
	 template0  | user       | UTF8     | en_US   | en_US | =c/user                  +
	            |            |          |         |       | user      =CTc/user      
	 template1  | user       | UTF8     | en_US   | en_US | =c/user                  +
	            |            |          |         |       | user      =CTc/user      
	(3 rows)



So what are the steps I should take? Delete an everything related to psql and reinstall everything?

Thanks for the help guys!

psql: FATAL: role &quot;postgres&quot; does not exist

postgreSQL: how to duplicate a row

I tried to run simple SQL command:

    select * from site_adzone;

and I got this error

&gt; ERROR:  permission denied for relation site_adzone

What could be the problem here?

I tried also to do select for other tables and got same issue. I also tried to do this:

    GRANT ALL PRIVILEGES ON DATABASE jerry to tom;

but I got this response from console

&gt; WARNING:  no privileges were granted for &quot;jerry&quot;

Does anyone have any idea what can be wrong?

Permission denied for relation

I am trying to compare the current date and time with dates and times specified in models using comparison operators:

    if challenge.datetime_start &lt;= datetime.now() &lt;= challenge.datetime_end:

The script errors out with: 

    TypeError: can&#39;t compare offset-naive and offset-aware datetimes

The models look like this:

    class Fundraising_Challenge(models.Model):
    	name = models.CharField(max_length=100)
    	datetime_start = models.DateTimeField()
    	datetime_end = models.DateTimeField()

I also have django using locale date and times.

What I haven&#39;t been able to find is the format django uses for DateTimeField().  Is it naive or aware?  And how do I get datetime.now() to recognize locale datetime?


Can&#39;t compare naive and aware datetime.now() &lt;= challenge.datetime_end

Is it possible to do that? If yes, then how do I do the conversion from [Joda-Time][1] to [Date][2] and vice versa?


  [1]: http://www.joda.org/joda-time/
  [2]: http://docs.oracle.com/javase/7/docs/api/java/util/Date.html

How to convert Joda-Time DateTime to java.util.Date and vice versa?

I want to add days in some date. I have a code like this: 

    DateTime endDate = Convert.ToDateTime(this.txtStartDate.Text); 
    Int64 addedDays = Convert.ToInt64(txtDaysSupp.Text); 
    endDate.AddDays(addedDays); 
    DateTime end = endDate; 
    this.txtEndDate.Text = end.ToShortDateString();

But this code is not working, days are not added! What the stupid mistake I&#39;m doing?

Datetime in C# add days

    // Difference from a date in the future:
    $a = new DateTime(&#39;2000-01-01&#39;);
    $b = new DateTime(&#39;2000-01-05&#39;);
    $interval = $b-&gt;diff($a);
    return $interval-&gt;days;             // Returns 4


    // Difference from a date in the past:
    $a = new DateTime(&#39;2000-01-01&#39;);
    $b = new DateTime(&#39;1999-12-28&#39;);
    $interval = $a-&gt;diff($b);           // Arguments swapped
    return $interval-&gt;days;             // Returns 4

Why do both of these functions return positive 4?
How do I return a negative number if a date is in the past?

Why does datetime-&gt;days always returns a positive number

Is there a way to extract month and day using isoformats? Lets assume today&#39;s date is March 8, 2013.

    &gt;&gt;&gt; d = datetime.date.today()
    &gt;&gt;&gt; d.month
    3
    &gt;&gt;&gt; d.day
    8

I want:

    &gt;&gt;&gt; d = datetime.date.today()
    &gt;&gt;&gt; d.month
    03
    &gt;&gt;&gt; d.day
    08

I can do this by writing if statements and concatenating a leading 0 in case the day or month is a single digit but was wondering whether there was an automatic way of generating what I want.

Content Type	Original Author	Original Content on Stackoverflow
Question	Daniel Magliola	View Question on Stackoverflow
Solution 1 - Sql	Erwin Brandstetter	View Answer on Stackoverflow
Solution 2 - Sql	Daniel Magliola	View Answer on Stackoverflow
Solution 3 - Sql	Willie Z	View Answer on Stackoverflow
Solution 4 - Sql	Rohil Patel	View Answer on Stackoverflow

How to add a variable number of hours to a date in PostgreSQL?

Sql Problem Overview

Sql Solutions

Solution 1 - Sql

Solution 2 - Sql

Solution 3 - Sql

Solution 4 - Sql

multiple instances of Mongo DB on same server

Rails generate Migration

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