`= NULL` is always `unknown` (this is piece of 3 state logic), but `WHERE` clause treats it as `false` and drops from the result set. So for `NULL` you should use `IS NULL`

Reasons are described here: https://stackoverflow.com/questions/1843451/why-does-null-null-evaluate-to-false-in-sql-server

To add to existing answers, it depends whether you have ANSI_NULLS on or not, when using &quot;= NULL&quot;.

    -- This will print TRUE
    SET ANSI_NULLS OFF;
    IF NULL = NULL
        PRINT &#39;TRUE&#39;
    ELSE
        PRINT &#39;FALSE&#39;
    
    -- This will print FALSE
    SET ANSI_NULLS ON;
    IF NULL = NULL
        PRINT &#39;TRUE&#39;
    ELSE
        PRINT &#39;FALSE&#39;



There is a difference between `IS NULL` and `= NULL` and this is because of the three-valued-logic of SQL:   

https://en.wikipedia.org/wiki/Null_%28SQL%29#Three-valued_logic_.283VL.29

Extract of a relevant paragraph:

&gt; **Challenges** 
&gt; 
&gt; Null has been the focus of controversy and a source of
&gt; debate because of its associated three-valued logic (3VL), special
&gt; requirements for its use in SQL joins, and the special handling
&gt; required by aggregate functions and SQL grouping operators. Computer
&gt; science professor Ron van der Meyden summarized the various issues as:
&gt; &quot;The inconsistencies in the SQL standard mean that it is not possible
&gt; to ascribe any intuitive logical semantics to the treatment of nulls
&gt; in SQL.&quot; Although various proposals have been made for resolving these
&gt; issues, the complexity of the alternatives has prevented their
&gt; widespread adoption.

The implementations of the major browsers seem to have problems with `text-transform: uppercase` with Turkish characters. As far as I know (I&#39;m not Turkish.) there are four different `i` characters: `ı i I İ` where the last two are the uppercase representations of the former two.

However applying `text-transform:uppercase` to `ı i`, the browsers (checked IE, Firefox, Chrome and Safari) results in `I I` which is not correct and may change the meaning of the words so much so that they become insults. (That&#39;s what I&#39;ve been told)

As my research for solutions did not reveal any my question is: Are there workarounds for this issue? The first workaround might be to remove `text-transform: uppercase` entirely but that&#39;s some sort of last resort.

Funny thing, the W3C has tests for this problem on their site, but lack of further information about this issue. http://www.w3.org/International/tests/tests-html-css/tests-text-transform/generate?test=5

I appreciate any help and looking forward to your answers :-)

Here&#39;s a [codepen][1]


  [1]: http://codepen.io/asim-coder/pen/pyYzOR

CSS: text-transform not working properly for Turkish characters

    30 days hath September,
       April, June and November,
     All the rest have 31,
       Excepting February alone
    (And that has 28 days clear,
       With 29 in each leap year).


Can I obtain this info anagrammatically?
(I don&#39;t mean the poem, of course)

How do I obtain the number of days within a given month using Joda-Time?

 I am surprised to see that IS NULL and =NULL are yielding different results in a select query. What is difference between them? When to use what. I would be glad if you can explain me in detail. 

Is there any difference between IS NULL and =NULL

<p>I am surprised to see that IS NULL and =NULL are yielding different results in a select query. What is difference between them? When to use what. I would be glad if you can explain me in detail.</p>


Background: I have a performance-critical query I&#39;d like to run and I don&#39;t care about dirty reads.

My question is; If I&#39;m using joins, do I have to specify the NOLOCK hint on those as well?

For instance; is:

    SELECT * FROM table1 a WITH (NOLOCK)
    INNER JOIN table2 b WITH (NOLOCK) ON a.ID = b.ID

Equivalent to:

    SELECT * FROM table1 a WITH (NOLOCK)
    INNER JOIN table2 b ON a.ID = b.ID

Or will I need to specify the `(NOLOCK)` hint on the join to ensure I&#39;m not locking the joined table?


SQL Server NOLOCK and joins

In my app I need to do a lot of INSERTS. Its a Java app and I am using plain JDBC to execute the queries. The DB being Oracle. I have enabled batching though, so it saves me network latencies to execute queries. But the queries execute serially as separate INSERTs:

    insert into some_table (col1, col2) values (val1, val2)
    insert into some_table (col1, col2) values (val3, val4)
    insert into some_table (col1, col2) values (val5, val6)

I was wondering if the following form of INSERT might be more efficient:

    insert into some_table (col1, col2) values (val1, val2), (val3, val4), (val5, val6)

i.e. collapsing multiple INSERTs into one.

Any other tips for making batch INSERTs faster?


Efficient way to do batch INSERTS with JDBC

I&#39;m trying to run a query that has a few columns that are a CLOB datatype. If i run the query like normal, all of those fields just have `(CLOB)` as the value.

I tried using `DBMS_LOB.substr(column`) and i get the error 

    ORA-06502: PL/SQL: numeric or value error: character string buffer too small

How can i query the CLOB column?

How to query a CLOB column in Oracle

I have something like:

    SELECT *
    FROM table
    WHERE id IN (118, 17, 113, 23, 72);

It returns the rows ordered by ID, ascending. Is there a way to get back the rows in the order specified in the `IN` clause?

Sort the rows according to the order specified in WHERE IN clause

&lt;!-- language-all: lang-sql --&gt;

As the title suggests, I&#39;d like to select the first row of each set of rows grouped with a `GROUP BY`.

Specifically, if I&#39;ve got a `purchases` table that looks like this:

    SELECT * FROM purchases;

**My Output:**


id | customer | total
---|----------|------
 1 | Joe      | 5
 2 | Sally    | 3
 3 | Joe      | 2
 4 | Sally    | 1


I&#39;d like to query for the `id` of the largest purchase (`total`) made by each `customer`. Something like this:

    SELECT FIRST(id), customer, FIRST(total)
    FROM  purchases
    GROUP BY customer
    ORDER BY total DESC;

**Expected Output:**

|FIRST(id) | customer | FIRST(total)|
|----------|----------|-------------|
|        1 | Joe      | 5|
|        2 | Sally    | 3|


Select first row in each GROUP BY group?

I have three stored procedures `Sp1`, `Sp2` and `Sp3`.

The first one (`Sp1`) will execute the second one (`Sp2`) and save returned data into `@tempTB1` and the second one will execute the third one (`Sp3`) and save data into `@tempTB2`.

If I execute the `Sp2` it will work and it will return me all my data from the `Sp3`, but the problem is in the `Sp1`, when I execute it it will display this error:

&gt; INSERT EXEC statement cannot be nested

I tried to change the place of `execute Sp2` and it display me another error:

&gt; Cannot use the ROLLBACK statement
&gt; within an INSERT-EXEC statement.

Errors: &quot;INSERT EXEC statement cannot be nested.&quot; and &quot;Cannot use the ROLLBACK statement within an INSERT-EXEC statement.&quot; How to solve this?

I am looking for a SQL Server function to return the minimum value for datetime, namely January 1, 1753. I&#39;d rather not hardcode that date value into my script.

Does anything like that exist? (For comparison, in C#, I could just do `DateTime.MinValue)`
Or would I have to write this myself?

I am using Microsoft SQL Server 2008 Express.

SQL Server function to return minimum date (January 1, 1753)

I have an MS SQL Server 2008 Express system which contains a database that I would like to &#39;copy and rename&#39; (for testing purposes) but I am unaware of a simple way to achieve this.

I notice that in the R2 version of SQL Server there is a copy database wizard, but sadly I can&#39;t upgrade.




The database in question is around a gig.
I attempted to restore a backup of the database I want to copy into a new database, but with no luck.


How can I clone an SQL Server database on the same server in SQL Server 2008 Express?

I was wondering if there was a way to do this in MS SQL Server 2005:

      DECLARE @theDate varchar(60)
      SET @theDate = &#39;&#39;&#39;2010-01-01&#39;&#39; AND &#39;&#39;2010-08-31 23:59:59&#39;&#39;&#39;

      SELECT	AdministratorCode, 
				SUM(Total) as theTotal, 
				SUM(WOD.Quantity) as theQty, 
				AVG(Total) as avgTotal, 
				(SELECT SUM(tblWOD.Amount)
					FROM tblWOD
					JOIN tblWO on tblWOD.OrderID = tblWO.ID
					WHERE tblWO.Approved = &#39;1&#39; 
					AND tblWO.AdministratorCode = tblWO.AdministratorCode
					AND tblWO.OrderDate BETWEEN @theDate
				)
     ... etc

Is this possible to do?

Declare Variable for a Query String

Executing dynamic SQL as follows in Stored Procedure:

    DECLARE @sqlCommand nvarchar(1000)
    DECLARE @city varchar(75)
    SET @city = &#39;London&#39;
    SET @sqlCommand = &#39;SELECT COUNT(*) FROM customers WHERE City = @city&#39;
    EXECUTE sp_executesql @sqlCommand, N&#39;@city nvarchar(75)&#39;, @city = @city

How do I use the count(*) column value as return value in the SP?



Getting result of dynamic SQL into a variable for sql-server

How can rows with non-ASCII characters be returned using SQL Server?  
If you can show how to do it for one column would be great.  

I am doing something like this now, but it is not working

    select *
    from Staging.APARMRE1 as ar
    where ar.Line like &#39;%[^!-~ ]%&#39;

**For extra credit,** if it can span _all_ `varchar` columns in a table, that would be outstanding! In this solution, it would be nice to return three columns:
  
* The identity field for that record. (This will allow the whole record to be reviewed with another query.)
* The column name
* The text with the invalid character

&lt;!-- language: lang-none --&gt;

     Id | FieldName | InvalidText       |
    ----+-----------+-------------------+
     25 | LastName  | Sol&#237;s             |
     56 | FirstName | Fran&#231;ois          |
    100 | Address1  | 123 &#220;mlaut street |

Invalid characters would be any outside the range of SPACE (32&lt;sub&gt;10&lt;/sub&gt;) through `~` (127&lt;sub&gt;10&lt;/sub&gt;)



Find non-ASCII characters in varchar columns using SQL Server

How can you tell what Tables are taking up the most space in a SQL Server 2005 Database?  

I am sure there is some System Stored Procedure that shows this information.

I have a TEST database that grew from 1tb to 23tb. We are currently doing a lot of client conversion testing in the database, which entails running the same conversion Stored Procedure multiple times. It does DELETEs which I am sure is increasing the Transaction Log. But this got me thinking to ask this question.

# info
the big problem is the dbo.Download table, it creates massive storage that is actually not needed, I had 3GB before truncating it, then 52MB ;)

How can you tell what Tables are taking up the most space in a SQL Server 2005 Database?

What are the differences between the `SET` and `SELECT` statements when assigning variables in T-SQL?

Content Type	Original Author	Original Content on Stackoverflow
Question	satya	View Question on Stackoverflow
Solution 1 - Sql	Andrey	View Answer on Stackoverflow
Solution 2 - Sql	AdaTheDev	View Answer on Stackoverflow
Solution 3 - Sql	Markus Winand	View Answer on Stackoverflow

Is there any difference between IS NULL and =NULL

Sql Problem Overview

Sql Solutions

Solution 1 - Sql

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Solution 3 - Sql

How do I obtain the number of days within a given month using Joda-Time?

CSS: text-transform not working properly for Turkish characters

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