try this:

    SELECT NEWID()

hope helped you

**What is a GUID?** GUID is a 16 byte binary SQL Server data type that is globally unique across tables, databases, and servers. The term GUID stands for Globally Unique Identifier and it is used interchangeably with UNIQUEIDENTIFIER.

To create a GUID in SQL Server, the NEWID() function is used as shown below:

    SELECT NEWID()

Execute the above line of SQL multiple times and you will see a different value every time. This is because the NEWID() function generates a unique value whenever you execute it.

To declare a variable of type GUID, the keyword used is UNIQUEIDENTIFIER as mentioned in the script below:

    DECLARE @UNI UNIQUEIDENTIFIER;
    SET @UNI = NEWID(); 
    SELECT @UNI;

As mentioned earlier, GUID values are unique across tables, databases, and servers. GUIDs can be considered as global primary keys. Local primary keys are used to uniquely identify records within a table. On the other hand, GUIDs can be used to uniquely identify records across tables, databases, and servers.

**For Example:**

    create table AspNetUsers
    (
    Id UNIQUEIDENTIFIER PRIMARY KEY default NEWID(),
    Name nvarchar(200)
    )
    
    INSERT INTO AspNetUsers VALUES (default,&#39;Shane&#39;)
    INSERT INTO AspNetUsers VALUES (default,&#39;Jonny&#39;)
    
    select * from AspNetUsers

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/LYR5C.png

A aspnet role created manually 

    DECLARE @ID UNIQUEIDENTIFIER
    SET @ID = NEWID()
     
    DECLARE @STAMP UNIQUEIDENTIFIER
    SET @STAMP = NEWID()
    
    INSERT INTO [dbo].[AspNetRoles]
               ([Id]
               ,[Name]
               ,[NormalizedName]
               ,[ConcurrencyStamp])
         VALUES
               (@ID
               ,&#39;Admin&#39;
               ,&#39;ADMIN&#39;
               ,@STAMP)

I&#39;m trying to push a docker image to the AWS ECR repository using the aws-cli.

 - I just run the `get-login` command
 - execute the output (which returns `login succeeded`) 
 - then try to push a docker image then I get the
   message:  
`denied: Your Authorization Token has expired. Please run
   &#39;aws ecr get-login&#39; to fetch a new one.`

I don&#39;t know whats going wrong,  I&#39;m pushing to the right repo, the time on my mac is correct. 
This was working before, but since I reinstalled my mac and upgraded to macOS Sierra it&#39;s not working anymore, so probably related to that.

My `aws --version` output:

`aws-cli/1.11.34 Python/2.7.10 Darwin/16.3.0 botocore/1.4.91`

The complete output of the commands I run:

    $ aws ecr get-login --region eu-west-1
    docker login -u AWS -p AQECAHh....b6Wk -e none https://1234567890.dkr.ecr.eu-west-1.amazonaws.com
    $ docker login -u AWS -p AQECAHh....b6Wk -e none https://1234567890.dkr.ecr.eu-west-1.amazonaws.com
    Flag --email has been deprecated, will be removed in 1.13.
    Login Succeeded
    $ docker push 1234567890.dkr.ecr.eu-west-1.amazonaws.com/service-web:latest
    The push refers to a repository [1234567890.dkr.ecr.eu-west-1.amazonaws.com/service-web]
    c1f87971dfa9: Preparing 
    2eb644aea3de: Preparing 
    9c8843ffe48e: Preparing 
    39bb58d049d4: Preparing 
    f053bc969599: Preparing 
    7169084246b8: Waiting 
    bb134a1936fd: Waiting 
    184e76848a1c: Waiting 
    75c8fcf65748: Waiting 
    eb9b9ee1ea58: Waiting 
    f4bf35723edd: Waiting 
    ddffe1a64b3c: Waiting 
    fd1a1154db16: Waiting 
    b542e946067a: Waiting 
    d49ed2a5e1ed: Waiting 
    bb39b980367a: Waiting 
    25b8358d062f: Waiting 
    997eee521fc7: Waiting 
    50b5447183a8: Waiting 
    4339b5cb0e1d: Waiting 
    3dbd4a53b21b: Waiting 
    2bec16216500: Waiting 
    b9fd8e264df6: Waiting 
    b6ca02dfe5e6: Waiting 
    denied: Your Authorization Token has expired. Please run &#39;aws ecr get-login&#39; to fetch a new one.



`Authorization Token has expired` issue AWS-CLI on MacOS Sierra

## Example Problem
As a simple example, consider the numpy array `arr` as defined below:

    import numpy as np
    arr = np.array([[5, np.nan, np.nan, 7, 2],
                    [3, np.nan, 1, 8, np.nan],
                    [4, 9, 6, np.nan, np.nan]])
where `arr` looks like this in console output:

    array([[  5.,  nan,  nan,   7.,   2.],
           [  3.,  nan,   1.,   8.,  nan],
           [  4.,   9.,   6.,  nan,  nan]])

I would now like to row-wise &#39;forward-fill&#39; the `nan` values in array `arr`. By that I mean replacing each `nan` value with the nearest valid value from the left. The desired result would look like this:

    array([[  5.,   5.,   5.,  7.,  2.],
           [  3.,   3.,   1.,  8.,  8.],
           [  4.,   9.,   6.,  6.,  6.]])

***
## Tried thus far
I&#39;ve tried using for-loops:

    for row_idx in range(arr.shape[0]):
        for col_idx in range(arr.shape[1]):
            if np.isnan(arr[row_idx][col_idx]):
                arr[row_idx][col_idx] = arr[row_idx][col_idx - 1]

I&#39;ve also tried using a pandas dataframe as an intermediate step (since pandas dataframes have a very neat built-in method for forward-filling):

    import pandas as pd
    df = pd.DataFrame(arr)
    df.fillna(method=&#39;ffill&#39;, axis=1, inplace=True)
    arr = df.as_matrix()

Both of the above strategies produce the desired result, but I keep on wondering: wouldn&#39;t a strategy that uses only numpy vectorized operations be the most efficient one?

***
## Summary
Is there another more efficient way to &#39;forward-fill&#39; `nan` values in numpy arrays? (e.g. by using numpy vectorized operations)

***
# Update: Solutions Comparison
I&#39;ve tried to time all solutions thus far. This was my setup script:

    import numba as nb
    import numpy as np
    import pandas as pd

    def random_array():
        choices = [1, 2, 3, 4, 5, 6, 7, 8, 9, np.nan]
        out = np.random.choice(choices, size=(1000, 10))
        return out

    def loops_fill(arr):
        out = arr.copy()
        for row_idx in range(out.shape[0]):
            for col_idx in range(1, out.shape[1]):
                if np.isnan(out[row_idx, col_idx]):
                    out[row_idx, col_idx] = out[row_idx, col_idx - 1]
        return out

    @nb.jit
    def numba_loops_fill(arr):
        &#39;&#39;&#39;Numba decorator solution provided by shx2.&#39;&#39;&#39;
        out = arr.copy()
        for row_idx in range(out.shape[0]):
            for col_idx in range(1, out.shape[1]):
                if np.isnan(out[row_idx, col_idx]):
                    out[row_idx, col_idx] = out[row_idx, col_idx - 1]
        return out

    def pandas_fill(arr):
        df = pd.DataFrame(arr)
        df.fillna(method=&#39;ffill&#39;, axis=1, inplace=True)
        out = df.as_matrix()
        return out

    def numpy_fill(arr):
        &#39;&#39;&#39;Solution provided by Divakar.&#39;&#39;&#39;
        mask = np.isnan(arr)
        idx = np.where(~mask,np.arange(mask.shape[1]),0)
        np.maximum.accumulate(idx,axis=1, out=idx)
        out = arr[np.arange(idx.shape[0])[:,None], idx]
        return out



followed by this console input:

    %timeit -n 1000 loops_fill(random_array())
    %timeit -n 1000 numba_loops_fill(random_array())
    %timeit -n 1000 pandas_fill(random_array())
    %timeit -n 1000 numpy_fill(random_array())

resulting in this console output:

    1000 loops, best of 3: 9.64 ms per loop
    1000 loops, best of 3: 377 &#181;s per loop
    1000 loops, best of 3: 455 &#181;s per loop
    1000 loops, best of 3: 351 &#181;s per loop

Most efficient way to forward-fill NaN values in numpy array

I need to create an Id as Guid in SQL(no identity) How I can do this? I defined the Id as uniqueidentifier but what is save in Db is 00000000-0000-0000-0000-000000000000

How to generate a Guid in SQL Server?

<p>I need to create an Id as Guid in SQL(no identity) How I can do this? I defined the Id as uniqueidentifier but what is save in Db is 00000000-0000-0000-0000-000000000000</p>


I am new to PostgresSQL.I tried 

    select * from employee where employee_name=&quot;elina&quot;;

But that results error as follows:

    ERROR: column &quot;elina&quot; does not exist.
Then I tried by replacing double quotes with single quotes as follows:

    select * from employee where employee_name=&#39;elina&#39;;

It result fine..So what is the difference between single quotes and double quotes in postgresql.If we can&#39;t use double quotes in postgres query,then if any other use for this double quotes in postgreSQL?

What is the difference between single quotes and double quotes in PostgreSQL?

I&#39;m writing a `Java` application to automatically build and run SQL queries. For many tables my code works fine but on a certain table it gets stuck by throwing the following exception:

    Exception in thread &quot;main&quot; org.postgresql.util.PSQLException: ERROR: column &quot;continent&quot; does not exist
      Hint: Perhaps you meant to reference the column &quot;countries.Continent&quot;.
      Position: 8

The query that has been run is the following:

    SELECT Continent
    FROM network.countries
    WHERE Continent IS NOT NULL
    AND Continent &lt;&gt; &#39;&#39;
    LIMIT 5

This essentially returns `5` non-empty values from the column.

I don&#39;t understand why I&#39;m getting the &quot;column does not exist&quot; error when it clearly does in [pgAdmin 4][1]. I can see that there is a schema with the name `Network` which contains the table `countries` and that table has a column called `Continent` just as expected.

Since all column, schema and table names are retrieved by the application itself I don&#39;t think there has been a spelling or semantical error so why does [PostgreSQL][2] cause problems regardless? Running the query in pgAdmin4 nor using the suggested `countries.Continent` is working.

My PostgreSQL version is the newest as of now:

    $ psql --version
    psql (PostgreSQL) 9.6.1

How can I successfully run the query?

  [1]: https://www.pgadmin.org/download/windows4.php
  [2]: https://www.postgresql.org/

PostgreSQL &quot;Column does not exist&quot; but it actually does

Consider:

    ./mysqladmin -u root -p** &#39;_redacted_&#39;  

Output (including typing the password):

&gt; Enter password: 
&gt;
&gt; mysqladmin: connect to server at &#39;localhost&#39; failed error:  
&gt; **&#39;Access denied for user &#39;root&#39;@&#39;localhost&#39; (using password: YES)&#39;**

How can I fix this?


MySQL Error: : &#39;Access denied for user &#39;root&#39;@&#39;localhost&#39;

I would like to include null values in an Apache Spark join.  Spark doesn&#39;t include rows with null by default.

Here is the default Spark behavior.

&lt;!-- language: scala --&gt;

    val numbersDf = Seq(
      (&quot;123&quot;),
      (&quot;456&quot;),
      (null),
      (&quot;&quot;)
    ).toDF(&quot;numbers&quot;)
    
    val lettersDf = Seq(
      (&quot;123&quot;, &quot;abc&quot;),
      (&quot;456&quot;, &quot;def&quot;),
      (null, &quot;zzz&quot;),
      (&quot;&quot;, &quot;hhh&quot;)
    ).toDF(&quot;numbers&quot;, &quot;letters&quot;)
    
    val joinedDf = numbersDf.join(lettersDf, Seq(&quot;numbers&quot;))

Here is the output of `joinedDf.show()`:


&lt;!-- language: none --&gt;

    +-------+-------+
    |numbers|letters|
    +-------+-------+
    |    123|    abc|
    |    456|    def|
    |       |    hhh|
    +-------+-------+

This is the output I would like:


&lt;!-- language: none --&gt;

    +-------+-------+
    |numbers|letters|
    +-------+-------+
    |    123|    abc|
    |    456|    def|
    |       |    hhh|
    |   null|    zzz|
    +-------+-------+

Including null values in an Apache Spark Join

I&#39;m getting the following error when doing the following type of insert:

Query:

    INSERT INTO accounts (type, person_id) VALUES (&#39;PersonAccount&#39;, 1) ON
    CONFLICT (type, person_id) WHERE type = &#39;PersonAccount&#39; DO UPDATE SET
    updated_at = EXCLUDED.updated_at RETURNING *

Error:

&gt; SQL execution failed (Reason: ERROR: there is no unique or exclusion
&gt; constraint matching the ON CONFLICT specification)

I also have an unique INDEX:

    CREATE UNIQUE INDEX uniq_person_accounts ON accounts USING btree (type,
    person_id) WHERE ((type)::text = &#39;PersonAccount&#39;::text);

The thing is that sometimes it works, but not every time. I *randomly* get
that exception, which is really strange. It seems that it can&#39;t access that
INDEX or it doesn&#39;t know it exists.

Any suggestion?

I&#39;m using PostgreSQL 9.5.5.

Example while executing the code that tries to find or create an account:

    INSERT INTO accounts (type, person_id, created_at, updated_at) VALUES (&#39;PersonAccount&#39;, 69559, &#39;2017-02-03 12:09:27.259&#39;, &#39;2017-02-03 12:09:27.259&#39;) ON CONFLICT (type, person_id) WHERE type = &#39;PersonAccount&#39; DO UPDATE SET updated_at = EXCLUDED.updated_at RETURNING *
     SQL execution failed (Reason: ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification)

In this case, I&#39;m sure that the account does not exist. Furthermore, it never outputs the error when the person has already an account. The problem is that, in some cases, it also works if there is no account yet. The query is exactly the same. 

No unique or exclusion constraint matching the ON CONFLICT

I&#39;m having major SQL performance problems when using async calls. I have created a small case to demonstrate the problem.

I have create a database on a SQL Server 2016 which resides in our LAN (so not a localDB).

In that database, I have a table `WorkingCopy` with 2 columns: 

    Id (nvarchar(255, PK))
    Value (nvarchar(max))

**DDL**

    CREATE TABLE [dbo].[Workingcopy]
    (
  	    [Id] [nvarchar](255) NOT NULL, 
 	    [Value] [nvarchar](max) NULL, 

	    CONSTRAINT [PK_Workingcopy] 
            PRIMARY KEY CLUSTERED ([Id] ASC)
	                    WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, 
                              IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, 
                              ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
    ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

In that table, I have inserted a single record (`id`=&#39;PerfUnitTest&#39;, `Value` is a 1.5mb string (a zip of a larger JSON dataset)).

Now, if I execute the query in SSMS :

    SELECT [Value] 
    FROM [Workingcopy] 
    WHERE id = &#39;perfunittest&#39;

I immediately get the result, and I see in SQL Servre Profiler that the execution time was around 20 milliseconds. All normal.

When executing the query from .NET (4.6) code using a plain `SqlConnection` :

	// at this point, the connection is already open
	var command = new SqlCommand($&quot;SELECT Value FROM WorkingCopy WHERE Id = @Id&quot;, _connection);
	command.Parameters.Add(&quot;@Id&quot;, SqlDbType.NVarChar, 255).Value = key;

	string value = command.ExecuteScalar() as string;
			
The execution time for this is also around 20-30 milliseconds. 

But when changing it to async code : 

    string value = await command.ExecuteScalarAsync() as string;

The execution time is suddenly **1800 ms** ! Also in SQL Server Profiler, I see that the query execution duration is more than a second. Although the executed query reported by the profiler is exactly the same as the non-Async version.

But it gets worse. If I play around with the Packet Size in the connection string, I get the following results :

&gt; Packet size  32768 : [TIMING]: ExecuteScalarAsync in SqlValueStore -&gt;
&gt; elapsed time : 450 ms
&gt; 
&gt; Packet Size 4096 : [TIMING]: ExecuteScalarAsync in SqlValueStore -&gt;
&gt; elapsed time : 3667 ms
&gt; 
&gt; Packet size  512 : [TIMING]: ExecuteScalarAsync in SqlValueStore -&gt;
&gt; elapsed time : 30776 ms

**30,000 ms**!! That&#39;s over a 1000x slower than the non-async version. And SQL Server Profiler reports that the query execution took over 10 seconds. That doesn&#39;t even explain where the other 20 seconds are gone to!

Then I&#39;ve switched back to the sync version and also played around with the Packet Size, and although it did impact a little the execution time, it was nowhere as dramatic as with the async version.

As a sidenote, if it put just a small string (&lt; 100bytes) into the value, the async query execution is just as fast as the sync version (result in 1 or 2 ms).

I&#39;m really baffled by this, especially since I&#39;m using the built-in `SqlConnection`, not even an ORM. Also when searching around, I found nothing which could explain this behavior. Any ideas?

Horrible performance using SqlCommand Async methods with large data

Looking to pass a list of User IDs to return a list names. I have a plan to handle the outputed names (with a COALESCE something or other) but trying to find the best way to pass in the list of user IDs.
The guts of my sproc will look something like this:

    create procedure [dbo].[get_user_names]
    @user_id_list, --which would equal a list of incoming ID numbers like (5,44,72,81,126)
    @username varchar (30) output
    as
    select last_name+&#39;, &#39;+first_name 
    from user_mstr
    where user_id in @user_id_list

Passing the values for @user_id_list is my main concern here.


How do I pass a list as a parameter in a stored procedure?

I have downloaded the SQL Server Management Studio (SSMS) 2016 to recover a huge .bak file which is an old backup of a database. But first of all I need to connect to a DB Server.

After install, I execute SSMS and it asks me to connect to a DB Server. I don&#39;t have any and I saw that it is possible to create a &quot;local&quot; db by typing only a dot &#39;.&#39; for Server Name and use Windows authentication. 

It is not working; how to do it?

How to connect to a local database in SQL Server Management Studio?

I&#39;ve used SQL Server Management Studio before, but only when the server is already up and running.

I need to start from the beginning and create my own instance on the local computer.

The instructions I&#39;m getting, is just put &quot;.&quot; on the server name and use Windows Authentication. But that gives me a &quot;server not found&quot; error.

Can someone please help? I&#39;m using SQL Server 2012 Management Studio.

I really thought it would be just like Access, create my tables and start creating queries.

Create Local SQL Server database

I am trying to do this:

    ALTER TABLE CompanyTransactions DROP COLUMN Created

But I get this:

&gt;Msg 5074, Level 16, State 1, Line 2
The object &#39;DF__CompanyTr__Creat__0CDAE408&#39; is dependent on column &#39;Created&#39;.
Msg 4922, Level 16, State 9, Line 2
ALTER TABLE DROP COLUMN Created failed because one or more objects access this column.

This is a code first table.  Somehow the migrations have become all messed up and I am trying to manually roll back some changed.

I have *no* idea what this is:

    DF__CompanyTr__Creat__0CDAE408

Content Type	Original Author	Original Content on Stackoverflow
Question	Alma	View Question on Stackoverflow
Solution 1 - Sql	Amazigh.Ca	View Answer on Stackoverflow
Solution 2 - Sql	Manish Kumar Gurjar	View Answer on Stackoverflow
Solution 3 - Sql	Diego Venâncio	View Answer on Stackoverflow

How to generate a Guid in SQL Server?

Sql Problem Overview

Sql Solutions

Solution 1 - Sql

Solution 2 - Sql

Solution 3 - Sql

Most efficient way to forward-fill NaN values in numpy array

`Authorization Token has expired` issue AWS-CLI on MacOS Sierra

Attributions