    DECLARE @uuid VARCHAR(50)
    SET @uuid = &#39;a89b1acd95016ae6b9c8aabb07da2010&#39;
    SELECT  CAST(
            SUBSTRING(@uuid, 1, 8) + &#39;-&#39; + SUBSTRING(@uuid, 9, 4) + &#39;-&#39; + SUBSTRING(@uuid, 13, 4) + &#39;-&#39; +
            SUBSTRING(@uuid, 17, 4) + &#39;-&#39; + SUBSTRING(@uuid, 21, 12)
            AS UNIQUEIDENTIFIER)



It would make for a handy function. Also, note I&#39;m using STUFF instead of SUBSTRING.

    create function str2uniq(@s varchar(50)) returns uniqueidentifier as begin
        -- just in case it came in with 0x prefix or dashes...
        set @s = replace(replace(@s,&#39;0x&#39;,&#39;&#39;),&#39;-&#39;,&#39;&#39;)
        -- inject dashes in the right places
        set @s = stuff(stuff(stuff(stuff(@s,21,0,&#39;-&#39;),17,0,&#39;-&#39;),13,0,&#39;-&#39;),9,0,&#39;-&#39;)
        return cast(@s as uniqueidentifier)
    end

your varchar col C:

    SELECT CONVERT(uniqueidentifier,LEFT(C, 8)
                                    + &#39;-&#39; +RIGHT(LEFT(C, 12), 4)
                                    + &#39;-&#39; +RIGHT(LEFT(C, 16), 4)
                                    + &#39;-&#39; +RIGHT(LEFT(C, 20), 4)
                                    + &#39;-&#39; +RIGHT(C, 12))

    SELECT CONVERT(uniqueidentifier,STUFF(STUFF(STUFF(STUFF(&#39;B33D42A3AC5A4D4C81DD72F3D5C49025&#39;,9,0,&#39;-&#39;),14,0,&#39;-&#39;),19,0,&#39;-&#39;),24,0,&#39;-&#39;))

The guid provided is not correct format(.net Provided guid).

    begin try
    select convert(uniqueidentifier,&#39;a89b1acd95016ae6b9c8aabb07da2010&#39;)
    end try
    begin catch
    print &#39;1&#39;
    end catch
	

I am new to JDBC and I am trying to make a connection to a MySQL database.
I am using Connector/J driver, but I cant find the JDBC connection string for my `Class.forName()` method.



What is the MySQL JDBC driver connection string?

Is it possible to preload or otherwise cache @font-face fonts, most likely with javascript, before the page loads so you don&#39;t get that ugly jump when the page finally does load?

Preloading @font-face fonts?

A table I have no control of the schema for, contains a column defined as varchar(50) which stores uniqueidentifiers in the format &#39;a89b1acd95016ae6b9c8aabb07da2010&#39; (no hyphens)

I want to convert these to uniqueidentifiers in SQL for passing to a .Net Guid. However, the following query lines don&#39;t work for me:

    select cast(&#39;a89b1acd95016ae6b9c8aabb07da2010&#39; as uniqueidentifier)
    select convert(uniqueidentifier, &#39;a89b1acd95016ae6b9c8aabb07da2010&#39;)

and result in:
&lt;pre&gt;Msg 8169, Level 16, State 2, Line 1
Conversion failed when converting from a character string to uniqueidentifier.&lt;/pre&gt;

The same queries using a hyphenated uniqueidentifier work fine but the data is not stored in that format.

Is there another (efficient) way to convert these strings to uniqueidentifiers in SQL. -- I don&#39;t want to do it in the .Net code.

Convert varchar to uniqueidentifier in SQL Server

A table I have no control of the schema for, contains a column defined as varchar(50) which stores uniqueidentifiers in the format 'a89b1acd95016ae6b9c8aabb07da2010' (no hyphens)
I want to convert these to uniqueidentifiers in SQL for passing to a .Net Guid. However, the following query lines don't work for me:
<pre><code class="hljs language-sql">select cast('a89b1acd95016ae6b9c8aabb07da2010' as uniqueidentifier)
select convert(uniqueidentifier, 'a89b1acd95016ae6b9c8aabb07da2010')
</code></pre>
and result in:
<pre>Msg 8169, Level 16, State 2, Line 1
Conversion failed when converting from a character string to uniqueidentifier.</pre>
The same queries using a hyphenated uniqueidentifier work fine but the data is not stored in that format.
Is there another (efficient) way to convert these strings to uniqueidentifiers in SQL. -- I don't want to do it in the .Net code.

I want to create a SQL interface on top of a non-relational data store. Non-relational data store, but it makes sense to access the data in a relational manner.

I am looking into using [ANTLR](http://www.antlr.org/) to produce an AST that represents the SQL as a relational algebra expression. Then return data by evaluating/walking the tree.

I have never implemented a parser before, and I would therefore like some advice on how to best implement a SQL parser and evaluator.

* Does the approach described above sound about right?
* Are there other tools/libraries I should look into? Like [PLY](http://www.dabeaz.com/ply/) or [Pyparsing](https://pypi.org/project/pyparsing/).
* Pointers to articles, books or source code that will help me is appreciated.

**Update:**

I implemented a simple SQL parser using pyparsing. Combined with Python code that implement the relational operations against my data store, this was fairly simple.

As I said in one of the comments, the point of the exercise was to make the data available to reporting engines. To do this, I probably will need to implement an ODBC driver. This is probably a lot of work.

Parsing SQL with Python

I&#39;m trying to flip a bit field in SQL Server using an update query, that is, I want to make all the 0&#39;s into 1&#39;s and vice versa. What&#39;s the most elegant solution? 

There doesn&#39;t seem to be a bitwise NOT operator in T-SQL (unless I&#39;m missing something obvious) and I haven&#39;t been able to find any other way of performing the update.


How to flip bit fields in T-SQL?

What is the purpose of naming your constraints (unique, primary key, foreign key)?

Say I have a table which is using natural keys as a primary key:

    CREATE TABLE Order
    (
        LoginName        VARCHAR(50)    NOT NULL,
        ProductName      VARCHAR(50)    NOT NULL,
        NumberOrdered    INT            NOT NULL,
        OrderDateTime    DATETIME       NOT NULL,
        PRIMARY KEY(LoginName, OrderDateTime)
    );

What benefits (if any) does naming my PK bring?

Eg.
Replace:

        PRIMARY KEY(LoginName, OrderDateTime)

With:

        CONSTRAINT Order_PK PRIMARY KEY(LoginName, OrderDateTime)

Sorry if my data model is not the best, I&#39;m new to this!

What is the purpose of constraint naming

This is a follow-on question from the one I asked [here][1].

Can constraints in a DB have the same name?

Say I have:

    CREATE TABLE Employer
    (
        EmployerCode    VARCHAR(20)    PRIMARY KEY,
        Address         VARCHAR(100)   NULL
    )


    CREATE TABLE Employee
    (
        EmployeeID      INT            PRIMARY KEY,
        EmployerCode    VARCHAR(20)    NOT NULL,
        CONSTRAINT employer_code_fk FOREIGN KEY (EmployerCode) REFERENCES Employer
    )


    CREATE TABLE BankAccount
    (
        BankAccountID   INT            PRIMARY KEY,
        EmployerCode    VARCHAR(20)    NOT NULL,
        Amount          MONEY          NOT NULL,
        CONSTRAINT employer_code_fk FOREIGN KEY (EmployerCode) REFERENCES Employer
    )

Is this allowable? Does it depend on the DBMS (I&#39;m on SQL Server 2005)? If it is not allowable, does anyone have any suggestions on how to work around it?


  [1]: https://stackoverflow.com/questions/1397440/

Can there be constraints with the same name in a DB?

After going thru some tutorials on SQL Server 2008&#39;s new feature &quot;SPARSE COLUMN&quot;, I have found that it doesn&#39;t take any space if the column value is 0 or NULL but when there is a value, it takes 4 times the space a regular(non sparse) column holds.

If my understanding is correct, then why I will go for that at the time of database design?
And if I use that, then at what situation will I be?

Also out of curiosity, how does no space get reserved when a column is defined as sparse column (I mean to say, what is the internal implementation for that?)


Why &amp; When should I use SPARSE COLUMN? (SQL SERVER 2008)

I&#39;ve seen many different ways to create and populate a numbers table.  However, what is the best way to create and populate one?  With &quot;best&quot; being defined from most to least important:

+ Table created with optimal indexing
+ rows generated fastest
+ simple code used to create and populate

If you don&#39;t know what a numbers table is, look here: [Why should I consider using an auxiliary numbers table?](https://web.archive.org/web/20100330144111/http://web.archive.org/web/20150411042510/http://sqlserver2000.databases.aspfaq.com/why-should-i-consider-using-an-auxiliary-numbers-table.html)

What is the best way to create and populate a numbers table?

I&#39;m using MS SQL 2005, and I want to check two dates for equality, but ignoring the time part.

I know I can make use of [DATEDIFF][1], but am concerned that it may be slow - this SP gets used in the DB a lot!

Any suggestions?


  [1]: http://msdn.microsoft.com/en-us/library/ms189794.aspx


&lt;b&gt;Edit:&lt;/b&gt; David Andres&#39; comment: &lt;blockquote&gt;&#39;&quot;comparison&quot; includes much more than equality&#39; &lt;/blockquote&gt; made me realise that I didn&#39;t make my question clear enough - I am actually just checking for equality, that is all.

Compare dates in T-SQL, ignoring the time part

So Oracle has NULLS FIRST, which I can use to have null values sorted at the top followed by my column value in descending order:

    ORDER BY date_sent NULLS FIRST

What is comparable in SQL Server?  There are these alternatives, assuming the date values are NULL or in the past:

    ORDER BY ISNULL(date_sent, GETDATE()) DESC
    ORDER BY (CASE WHEN t.setinactive IS NULL THEN 1 ELSE 2 END), t.setinactive DESC
    ORDER BY -CAST(date_sent as int) ASC

Any others?

SQL Server equivalent to Oracle&#39;s NULLS FIRST?

Consider the need to create a resultset of dates. We&#39;ve got start and end dates, and we&#39;d like to generate a list of dates in between.

    DECLARE  @Start datetime
             ,@End  datetime
    DECLARE @AllDates table
            (@Date datetime)

    SELECT @Start = &#39;Mar 1 2009&#39;, @End = &#39;Aug 1 2009&#39;
    
    --need to fill @AllDates. Trying to avoid looping. 
    -- Surely if a better solution exists.

Consider the current implementation with a `WHILE` loop:

    DECLARE @dCounter datetime
    SELECT @dCounter = @Start
    WHILE @dCounter &lt;= @End
    BEGIN
     INSERT INTO @AllDates VALUES (@dCounter)
     SELECT @dCounter=@dCounter+1 
    END

**Question:** How would you create a set of dates that are within a user-defined range using T-SQL? Assume SQL 2005+. If your answer is using SQL 2008 features, please mark as such.

Generate a resultset of incrementing dates in TSQL

I want to create a GUID and store it in the DB.

In C# a guid can be created using Guid.NewGuid().  This creates a 128 bit integer.  SQL Server has a uniqueidentifier column which holds a huge hexidecimal number.  

Is there a good/preferred way to make C# and SQL Server guids play well together? (i.e. create a guid using Guid.New() and then store it in the database using nvarchar or some other field ... or create some hexidecimal number of the form that SQL Server is expecting by some other means)



C# guid and SQL uniqueidentifier

Can anyone tell me if there is an equivalent of `SCOPE_IDENTITY()` when using GUIDs as a primary key in SQL Server?

I don&#39;t want to create the GUID first and save as a variable as we&#39;re using sequential GUIDs as our primary keys.

Any idea on what the best way to retrieve the last inserted GUID primary key?

SCOPE_IDENTITY() for GUIDs?

How would it be possible to generate a random, unique string using numbers and letters for use in a verify link? Like when you create an account on a website, and it sends you an email with a link, and you have to click that link in order to verify your account

How can I generate one of those using PHP?

How to generate a random, unique, alphanumeric string?

I&#39;d like to get an id unique to a computer with Java, on Windows, MacOS and, if possible, Linux. It could be a disk UUID, motherboard S/N...

`Runtime.getRuntime().exec` can be used (it is not an applet).

Ideas?

How to get a unique computer identifier in Java (like disk ID or motherboard ID)?

I&#39;m aware that MD5 has had some collisions but this is more of a high-level question about hashing functions. 

If MD5 hashes any arbitrary string into a 32-digit hex value, then according to the [Pigeonhole Principle][1] surely this can not be unique, as there are more unique arbitrary strings than there are unique 32-digit hex values.


  [1]: https://en.wikipedia.org/wiki/Pigeonhole_principle &quot;Pigeonhole Principle&quot;

Content Type	Original Author	Original Content on Stackoverflow
Question	grenade	View Question on Stackoverflow
Solution 1 - Sql	Quassnoi	View Answer on Stackoverflow
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Solution 3 - Sql	manji	View Answer on Stackoverflow
Solution 4 - Sql	Matthew	View Answer on Stackoverflow
Solution 5 - Sql	user3082965	View Answer on Stackoverflow

Convert varchar to uniqueidentifier in SQL Server

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Preloading @font-face fonts?

What is the MySQL JDBC driver connection string?

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