The following command through sqllocaldb utility works for me.

    sqllocaldb stop mssqllocaldb
    sqllocaldb delete mssqllocaldb
    sqllocaldb start &quot;MSSQLLocalDB&quot;

[![enter image description here][1]][1]

After that I restarted the sql server management studio, and it is successfully established connection through `(LocalDB)\MSSQLLocalDB` 


  [1]: http://i.stack.imgur.com/Vqiv6.png

For this particular error, what gave me access to my MDF in VS2019 was:

 1. In Solution Explorer, right click your MDF file
 2. Detach

That was it and I now have access.  I was expecting to detach and attach, but that wasn&#39;t needed.

I also could not get to my (localdb) in SSMS either, so what helped me there was a solution by Leniel Maccaferri. Here is the link to his site, along with the excerpt that helped me:

https://www.leniel.net/2014/02/localdb-sqlserver-2012-cannot-open-database-requested-by-login-the-login-failed-error-4060.html



[![enter image description here][1]][1]

So guess what: the solution is ridiculously easy once you know what to do of course…

Click that Options &gt;&gt; button in Figure 1. Now select the Connection Properties tab.

SSMS Connect to Server | Connection Properties | Connect to database optionFigure 2 - SSMS Connect to Server | Connection Properties | Connect to database option

I had to type master in Connect to database field since I did not have it in the list of available databases.

Now click connect and you’re done.


  [1]: https://i.stack.imgur.com/xuIsg.png

How do I investigate a &quot;style sheet could not be loaded&quot; message in Firefox?  This message appears as a red bar below the page contents and above the developer tools.  How do I find out what file the browser is referring to?  I&#39;m running version 46.0 on Linux Mint 17.3.

**Update**

If I look at the console of the developer&#39;s tools in Firefox, it shows all the css files and says &quot;HTTP/1.1 200 OK&quot; against each file.

**Another Update**

This error bar comes and goes, it is not consistent for a particular page.

How do I investigate a &quot;style sheet could not be loaded&quot; message in Firefox?

I have started using the JSON data type in mysql 5.7. Is there a way to extract a value without the quotation marks? For instance when setting up a virtual index.

Example: 

    mysql&gt; INSERT INTO test (data) VALUES (&#39;{&quot;type&quot;: &quot;user&quot; , 
    &quot;content&quot; : { &quot;username&quot;: &quot;jdoe&quot;, &quot;firstname&quot; : &quot;John&quot;, &quot;lastname&quot; : &quot;Doe&quot; } }&#39;);

    mysql&gt; SELECT json_extract(data,&#39;$.type&#39;) FROM test;
    +-----------------------------+
    | json_extract(data,&#39;$.type&#39;) |
    +-----------------------------+
    | &quot;user&quot;                      |
    +-----------------------------+

How to get

    +-----------------------------+
    | json_extract(data,&#39;$.type&#39;) |
    +-----------------------------+
    | user                        |
    +-----------------------------+

?

Extract value without quotation mark from MySQL JSON data type

I am getting an error, While I am trying to connect (LocalDB)\MSSQLLocalDB through SQL Server management studio. I also tried to login with default database as master the error is same.

[![enter image description here][1]][1]
Here is the Server details.
[![enter image description here][2]][2]


  [1]: http://i.stack.imgur.com/Q3Gyb.png
  [2]: http://i.stack.imgur.com/dE9Aw.png

Cannot connect to (LocalDB)\MSSQLLocalDB -&gt; Login failed for user &#39;User-PC\User&#39;

<p>I am getting an error, While I am trying to connect (LocalDB)\MSSQLLocalDB through SQL Server management studio. I also tried to login with default database as master the error is same.</p>
<p><a href="http://i.stack.imgur.com/Q3Gyb.png" target="_blank" rel="noopener noreferrer"><img src="http://i.stack.imgur.com/Q3Gyb.png" alt="enter image description here"></a>
Here is the Server details.
<a href="http://i.stack.imgur.com/dE9Aw.png" target="_blank" rel="noopener noreferrer"><img src="http://i.stack.imgur.com/dE9Aw.png" alt="enter image description here"></a></p>


I am importing data from a MySQL database into a Pandas data frame. The following excerpt is the code that I am using:

    import mysql.connector as sql
    import pandas as pd
    
    db_connection = sql.connect(host=&#39;hostname&#39;, database=&#39;db_name&#39;, user=&#39;username&#39;, password=&#39;password&#39;)
    db_cursor = db_connection.cursor()
    db_cursor.execute(&#39;SELECT * FROM table_name&#39;)

    table_rows = db_cursor.fetchall()

    df = pd.DataFrame(table_rows)

When I print the data frame it does properly represent the data but my question is, is it possible to also keep the column names? Here is an example output:

                              0   1   2     3     4     5     6     7     8
    0  :ID[giA0CqQcx+(9kbuSKV== NaN NaN  None  None  None  None  None  None
    1  lXB+jIS)DN!CXmj&gt;0(P8^]== NaN NaN  None  None  None  None  None  None   
    2  lXB+jIS)DN!CXmj&gt;0(P8^]== NaN NaN  None  None  None  None  None  None   
    3  lXB+jIS)DN!CXmj&gt;0(P8^]== NaN NaN  None  None  None  None  None  None   
    4  lXB+jIS)DN!CXmj&gt;0(P8^]== NaN NaN  None  None  None  None  None  None   

What I would like to do is keep the column name, which would replace the pandas column indexes. For example, instead of having 0, the column name would be: &quot;First_column&quot; as in the MySQL table. Is there a good way to go about this? or is there a more efficient approach of importing data from MySQL into a Pandas data frame than mine?

Importing data from a MySQL database into a Pandas data frame including column names

How does SQL engines differ when we use equal sign and IN operator have same value? Does execution time changes?

1st one using equality check operator

    WHERE column_value = &#39;All&#39;

2nd one using `IN` operator and single value

    WHERE column_value IN (&#39;All&#39;)

Does SQL engine changes `IN` to `=` if only one value is there?

Is there any difference for same in MySQL and PostgreSQL?

Performance differences between equal (=) and IN with one literal value

Question is pretty much in the title. I can&#39;t find any detailed documentation regarding the differences.

I do notice a difference because when interchanging cube and groupBy function calls, I get different results. I noticed that for the result using &#39;cube&#39;, I got a lot of null values on the expressions I often grouped by.

What is the difference between cube, rollup and groupBy operators?

I would like to &quot;declare&quot; what are effectively multiple TEMP tables using the WITH statement. 
The query I am trying to execute is along the lines of:

    WITH table_1 AS (
    SELECT GENERATE_SERIES(&#39;2012-06-29&#39;, &#39;2012-07-03&#39;, &#39;1 day&#39;::INTERVAL) AS date
    )
    
    WITH table_2 AS (
    SELECT GENERATE_SERIES(&#39;2012-06-30&#39;, &#39;2012-07-13&#39;, &#39;1 day&#39;::INTERVAL) AS date
    )
    
    SELECT * FROM table_1
    WHERE date IN table_2

I&#39;ve read [PostgreSQL documentation][1] and researched into using multiple `WITH` statements and was unable to find an answer. 



  [1]: https://www.postgresql.org/docs/9.5/static/functions-srf.html

How to use multiple WITH statements in one PostgreSQL query?

What is the difference between `-&gt;&gt;` and `-&gt;` in SQL?

In this thread (https://stackoverflow.com/questions/19422233/check-if-field-exists-in-json-type-column-postgresql), the answerer basically recommends using,

    json-&gt;&#39;attribute&#39; is not null

instead of,

    json-&gt;&gt;&#39;attribute&#39; is not null

Why use a single arrow instead of a double arrow? In my limited experience, both do the same thing.

What is the difference between `-&gt;&gt;` and `-&gt;` in Postgres SQL?

When comparing an SQLServer project in Visual Studio 2015 Update 2 against a database SQL Server 2012, it shows the error &quot;Target is unavailable&quot; or &quot;Source is unavailable&quot; when change the direction.

It used to work properly a couple of months ago. Is there any workaround? I couldn&#39;t find any.



SQL Schema Comparison Error &quot;Target is unavailable&quot;

I came across an issue with EF creating terrible queries when searching on a string field. Its produced a query in the style of lazy programmers to encompass null checking which forces the whole index to be scanned. 

consider the following queries.

 1. Query 1

        var p1 = &quot;x&quot;;
        var r1 = ctx.Set&lt;E&gt;().FirstOrDefault(
                                subject =&gt;
                                    p1.Equals(subject.StringField));

 2. Query 2

        const string p2 = &quot;x&quot;;
        var r2 = ctx.Set&lt;E&gt;().FirstOrDefault(
                                subject =&gt;
                                    p2.Equals(subject.StringField));



Query 1 produces 

&lt;!-- language: lang-sql --&gt;

    WHERE ((&#39;x&#39; = [Extent2].[StringField]) OR ((&#39;x&#39; IS NULL) AND ([Extent2].[StringField] IS NULL))) 
and executes in 4 seconds

Query 2 produces

&lt;!-- language: lang-sql --&gt;

    WHERE (N&#39;x&#39; = [Extent2].[StringField]) 

and executes in 2 milliseconds

Does anyone know of any work arounds? (no the parameter cant be a const as it is entered by user input but cannot be null.)
 
N.B When profiled, both queries are prepared with sp_executesql by EF; as of-cause if they were just executed the query optimiser would negate the OR &#39;x&#39; IS NULL check.

[![for @Martin][1]][1]


  [1]: http://i.stack.imgur.com/wrysq.png

Why is EF generating SQL queries with unnecessary null-checks?

I am trying to parse out a value from a string that involves getting the [last][1] [index][2] of a [string][3].  Currently, I am doing a horrible hack that involves reversing a string:

    SELECT REVERSE(SUBSTRING(REVERSE(DB_NAME()), 1, 
        CHARINDEX(&#39;_&#39;, REVERSE(DB_NAME()), 1) - 1))

To me this code is nearly unreadable.  I just upgraded to SQL Server 2016 and I hoping there is a better way.
Is there?


  [1]: https://stackoverflow.com/questions/15709712/what-is-best-way-to-get-last-indexof-character-in-sql-2008
  [2]: https://stackoverflow.com/questions/1024978/find-index-of-last-occurrence-of-a-sub-string-using-t-sql
  [3]: http://www.sqlmatters.com/Articles/Searching%20a%20string%20for%20the%20last%20occurrence%20of%20a%20given%20string.aspx

Is there a LastIndexOf in SQL Server?

I have data in an Excel file - actually [XLSX][1] format since it is now 2020. My requirement is to get this data into SQL Server as follows:

 1. ad hoc, the use case being feeding tables with test data, or infrequent data loads of small amounts of data (say &lt; 3k rows), and

 2. In a repeatable, robust, and possibly automated way for a production system.

  [1]: https://en.wikipedia.org/wiki/Microsoft_Excel#Current_file_extensions



How can I import an Excel file into SQL Server?

I try to map my other DB to a user by going to &lt;br/&gt;Security &gt; Logins &gt; right click someuser &gt; Properties &gt; User Mapping &gt; Select DB &gt; set as db_owner and then ok, but I keep on getting an error saying 

&gt; User, group, or role &#39;someuser&#39; already exists in the current database. (Microsoft SQL Server, Error: 15023)

What is causing the error, and how do I map that user to the database? 

SQL Server User Mapping Error 15023

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;m trying to alter the length of the column &quot;Body&quot; in table &quot;Post&quot; like this:

    ALTER TABLE Post ALTER COLUMN Body nvarchar(8000) NOT NULL;

The column is defined as nvarchar(4000) and it gives me this error:

&gt; Msg 2717, Level 16, State 2, Line 1
The size (8000) given to the parameter &#39;Body&#39; exceeds the maximum allowed (4000).

How to alter column nvarchar length without drop

I notice that Database Diagrams are not supported in SSMS version 18, any idea why, and is there a way to get the same functionality?

And why is the T-SQL debugger gone now?

Content Type	Original Author	Original Content on Stackoverflow
Question	Musakkhir Sayyed	View Question on Stackoverflow
Solution 1 - Sql	Musakkhir Sayyed	View Answer on Stackoverflow
Solution 2 - Sql	James Lee	View Answer on Stackoverflow

Cannot connect to (LocalDB)\MSSQLLocalDB -> Login failed for user 'User-PC\User'

Sql Problem Overview

Sql Solutions

Solution 1 - Sql

Solution 2 - Sql

Extract value without quotation mark from MySQL JSON data type

How do I investigate a "style sheet could not be loaded" message in Firefox?

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