Today, I'm gonna talk about how to handle error in SQL Server using THROW. In versions prior to SQL Server 2012, you can use @@RAISE_ERROR to generate error messages dynamically or using the sys.messages catalog.

Consider the following example:

SELECT ROUND(800.0, -3)

On executing this statement, you get the following error:

This error is caused by the value does not fit into the decimal data type.

You can use @@RAISERROR to raise a message:

BEGIN TRY
SELECT ROUND(800.0, -3)
END TRY
BEGIN CATCH
DECLARE @ErrorMsg nvarchar(1000), @Severity int
SELECT @ErrorMsg = ERROR_MESSAGE(),
@Severity = ERROR_SEVERITY()
RAISERROR (@ErrorMsg, @Severity, 1)
END CATCH

Note: The old syntax of RAISERROR syntax specifying the error number and message number got deprecated (RAISEERROR 50005 ‘Exception Occurred’). Instead the new syntax RAISEERROR(50005, 10, 1) allowed you to specify the messageid, severity and state). For new applications use THROW.

However in SQL Server 2012 and above, there’s a better way to this without much efforts, using THROW. Consider the following code:

BEGIN TRY
SELECT ROUND(800.0, -3)
END TRY
BEGIN CATCH
THROW
END CATCH

As you can see, with just one word THROW, we were able to handle the error with grace and get a result too.

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If you want to know if a table has a primary key or foreign key, you can find out this in many ways. Just follow these steps on this tutorial.

Step 1

First, let us create these a table using code below:

CREATE TABLE product_master
(
prod_id INT PRIMARY KEY,
prod_name VARCHAR(100),
price DECIMAL(12,2)
)
GO
CREATE TABLE product_details
(
prod_id INT,
sales_date DATETIME,
sales_qty INT,
sales_amount DECIMAL(16,2)
)
GO
CREATE TABLE company_master
(
compnay_id INT,
company_name VARCHAR(100),
address VARCHAR(1000)
)
GO

Step 2

Now, let us create foreign key:

ALTER TABLE product_details ADD CONSTRAINT ck_item FOREIGN KEY(prod_id) REFERENCES product_master(prod_id)

Step 3

If you want to check if a table has a primary key, you can use the following methods:

1. Use sp_pkeys system stored procedure

The result will be:

2. Use Objectproperty function

SELECT
*
FROM
INFORMATION_SCHEMA.TABLES
WHERE
OBJECTPROPERTY(OBJECT_ID(TABLE_NAME),'TABLEHASPRIMARYKEY')=1 AND
TABLE_TYPE='BASE TABLE'
ORDER BY
TABLE_NAME

Step 4

If you want to check if a table has a foreign key, you can use the following method:

SELECT
*
FROM
INFORMATION_SCHEMA.TABLES
WHERE
OBJECTPROPERTY(OBJECT_ID(TABLE_NAME),'TABLEHASFOREIGNKEY')=1 AND
TABLE_TYPE='BASE TABLE'
ORDER BY
TABLE_NAME

And the result is:

Step 5

If you want to check for the tables that do not have primary key or foreign key, you can use the following method:

SELECT
*
FROM
INFORMATION_SCHEMA.TABLES
WHERE
OBJECTPROPERTY(OBJECT_ID(TABLE_NAME),'TABLEHASPRIMARYKEY')=0 AND
OBJECTPROPERTY(OBJECT_ID(TABLE_NAME),'TABLEHASFOREIGNKEY')=0 AND
TABLE_TYPE='BASE TABLE'
ORDER BY
TABLE_NAME

This is the result:

Easy right?

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In this post, I am going to explain how you can list all CONSTRAINT of database or table in SQl Server. When you are working on database sometimes you need to check or get the CONSTRAINT on database or table. Using below given query we can get the CONSTRAINT of table or database quickly.

Step 1

Query to list all fields of sys.objects:
SELECT * FROM sys.objects WHERE type_desc LIKE '%CONSTRAINT'
Using above query we get all fields of sys.objects.

Step 2

To get only Constraint name, tabe name and Constraint type I use the refined query mention below:
SELECT OBJECT_NAME(object_id) AS ConstraintName,
SCHEMA_NAME(schema_id) AS SchemaName,
OBJECT_NAME(parent_object_id) AS TableName,
type_desc AS ConstraintType
FROM sys.objects
WHERE type_desc LIKE '%CONSTRAINT'

Step 3

To get the Constraint detail of a particular table use the below given query:
SELECT OBJECT_NAME(object_id) AS ConstraintName,
SCHEMA_NAME(schema_id) AS SchemaName,
type_desc AS ConstraintType
FROM sys.objects
WHERE type_desc LIKE '%CONSTRAINT' AND OBJECT_NAME(parent_object_id)='Student_Register'

The last, replace the Student_Register with your database table name.

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Sometimes, you may want to delete rows because they are no longer needed, or they were incorrectly added in the first place. The DELETE statement is used to remove rows from a SQL Server table. A single DELETE statement can remove a single row, or number of rows. In this article, I will explore how to remove rows from a table using the DELETE statement.

Here is the basic syntax of the DELETE statement:

DELETE
[ TOP ( expression ) [ PERCENT ] ]
[ FROM ] <object>
[ <OUTPUT Clause> ]
[ WHERE <search_condition>]

( expression ) - is a number or an expression that equates to a number used to limit the number of rows deleted.

<object> - is the name of an object in a database from which you want to delete records

<OUTPUT Clause> - identifies the column values of the deleted rows to be returned from the DELETE statement

<search_condition> - the condition used to identify the rows to be deleted

In order to demonstrate how to use the DELETE statement I will be creating a DemoDelete table. Here is the code I used to create and populate my DemoDelete table.

USE tempdb;
GO
CREATE TABLE DemoDelete (ID int,
DeleteDesc varchar(100));
GO
INSERT INTO DemoDelete VALUES
(1,'Thing One'),
(2,'Thing Two'),
(3, 'The Cat'),
(4, 'Sally'),
(5, 'The Brother'),
(6, 'The Mother'),
(7, 'The Fish');

Deleting a Single Row Using WHERE Constraint

In order to delete a single row from a table you need to identify that row with a WHERE constraint. Below is some code that deletes a single row from my DemoDelete table:

DELETE FROM DemoDelete
WHERE DeleteDesc = 'The Mother';

In this code I used the DeleteDesc column to constrain the records that I would be deleting. By specifying that the DeleteDesc column value had to be equal to the value "The Mother", only one record in my table got deleted, because only one row in my table had that value. Now if my table contained a number of rows that had a column value of "The Mother" then all the rows that contained that value would be deleted.

If you are unsure of the rows you are identifying to be deleted using the above example, and you want to make sure the rows you have targeted with the WHERE constraint are correct, then you can first run a SELECT statement. After you are confident that your SELECT statement is selecting the rows you want to delete you can then convert it to a DELETE statement.

Using the TOP Clause to Delete a Single Row

You can also use the TOP clause to delete a single row. Below is an example where I used the TOP clause to delete one row from my DemoDelete table:

DELETE TOP (1) FROM DemoDelete;

This statement deleted a random row from my DemoDelete table. It was random because SQL Server does not guarantee a sorted set will be returned where it can delete the top record of the ordered set. When I review the records left in my table I see I deleted the record that had an Id value of 1 and a DeleteDesc of "Thing One". Note if I change the TOP clause to another number like 3, then this statement would delete the number of rows equal to the value specified.

Deleting the TOP 1 Records from a Sorted Set

If you want to delete the first record from a sorted set you need to write your TSQL DELETE statement similar to the following code:

DELETE TOP (1) FROM DemoDelete
WHERE ID in
(SELECT TOP (1) ID FROM DemoDelete
ORDER BY ID DESC);

In the above code I create a subquery that returned a single ID value based on the descending sort order of ID column value in my DemoDelete table. I then used the WHERE constraint to only delete records that had that ID value. I also place a TOP (1) clause on my DELETE statement to only delete a single row should my DemoDelete table contain multiple records with the same ID value. If you are following along you can see the above code deleted the DemoDelete record that had an ID value of 7.

Since my DemoDelete table did not contain multiple records with the same ID value I could have also deleted the largest ID value row by running the following code:

DELETE FROM DemoDelete
WHERE ID in
(SELECT TOP (1) ID FROM DemoDelete
ORDER BY ID DESC);

When I run this code against my DemoDelete table it will delete ID value of 5.

Using Another Table to Identify the Rows to Delete and the OUTPUT Clause

There are times when you might what to delete the rows in a table based on values from another table. An example of where you might want to do this is to remove rows from your inventory table based on some sales data. To demo this first I will need to generate another table that contains key values for the rows I want to delete. Here is the code to create and populate my other table:

CREATE TABLE RecordsToDelete (
DeleteDesc varchar(100));
GO
INSERT INTO RecordsToDelete VALUES
('Thing Two'),
('Sally');

At this point after running all my different DELETE statements against my DemoDelete table there are only three rows left in my table. By selecting all the rows in my DemoDelete table I see that these three rows are left:

ID DeleteDesc
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
2 Thing Two
3 The Cat
4 Sally

In order to use the RecordsToDelete table to delete specific records in my DemoDelete table I need to run the code below:

DELETE FROM DemoDelete
OUTPUT DELETED.*
FROM DemoDelete INNER JOIN RecordsToDelete
on DemoDelete.DeleteDesc = RecordsToDelete.DeleteDesc;

This code joins the table DemoDelete and RecordsToDelete based on the DeleteDesc column. When the DeleteDesc matches between the two tables the matched rows within the DemoDelete table are deleted.

My delete statement above also contains the OUTPUT clause. The OUTPUT clause is used to return the column values of the deleted rows that are identified in the OUTPUT clause. In the code above I specified "DELETED.*". The "*" means to return all the columns values from the DELETED rows. When I ran this code the following rows were returned:

ID DeleteDesc
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -
2 Thing Two
4 Sally

These returned rows could be used by your application for some purpose, like creating an audit trail.

Inserting OUTPUT Clause Data into a Table

There are times when you might retain the data created by the OUTPUT clause in a table instead of just returning the deleted row values to the application. To demonstrate running a DELETE statement that populates the row values being deleted into a table I will run the code below:

DECLARE @DeletedRows TABLE
(ID INT, DeleteDesc varchar(100));
DELETE FROM DemoDelete
OUTPUT DELETED.ID, DELETED.DeleteDesc
INTO @DeletedRows
WHERE DeleteDesc = 'The Cat';
SELECT * FROM @DeletedRows;

In this code sample I first created a table to contain my deleted rows. This table is a table variable name @DeletedRows. Next I ran my DELETE statement. This time my DELETE statement specified the deleted row output was to go into my table variable. That specification was made using the INTO clause of the DELETE statement.

The following output displayed the SELECT statement in the above code snippet:

ID DeleteDesc
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -
3 The Cat

In both of my examples that used the OUTPUT clause of the DELETE statement I specified "DELETED.*" to denote outputting all the column values for the rows being deleted. I could have specified the actual column values I wanted to output. The code below is equivalent to the code above.

DECLARE @DeletedRows TABLE
(ID INT, DeleteDesc varchar(100));
DELETE FROM DemoDelete
OUTPUT DELETED.ID, DELETED.DeleteDesc
INTO @DeletedRows
WHERE DeleteDesc = 'The Cat';
SELECT * FROM @DeletedRows;

In this code you can see I specified "DELETED.ID, DELETED.DeleteDesc", instead of "DELETE.*". You can verify this code is equivalent by inserting the "The Cat" row back into the DemoDelete table and then running the code above.

As you can see there are multiple ways to delete rows from a SQL Server table. You can use the WHERE clause to identify specific criteria for the rows that need to be deleted. You can join a table to the table in which you are deleting rows to identify which rows to delete. You can even use the TOP clause to restrict the number of rows that will be deleted. The article should help you with developing your DELETE statement next time you have to remove some rows from a SQL Server table.

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Recently one of our costumer emailed us below question:

Hi Hostforlife,
Need your urgent help. In recent past, we have been attacked by the hacker who was able to get in to our SQL Server via sysadmin account and made big damage to our data. To make sure it doesn’t happen in future, I have taken task to find out SQL Server password which are weak.
Do you have any suggestions for me?

This is one of the area which is always haunting all SQL DBAs. There are recommendations to use Windows Authentication to connect to SQL Server and that would save from all such problem. But it is not always feasible to use Windows Authentication. Now, if you decided to choose SQL Authentication, there is a setting which is “Enforce Password Policy” which would ensure that you are choosing a strong password.

If recommendations are not followed, you might end up in situation where SQL Logins have weak and basic passwords. SQL Server has provided a function PWDCOMPARE which can become very useful to find known password. Below are few example use of this out of box funtion:

SELECT NAME,
NAME 'password'
FROM   sys.sql_logins
WHERE  Pwdcompare(NAME, password_hash) = 1
UNION
SELECT NAME,
'<blank>' AS 'password'
FROM   sys.sql_logins
WHERE  Pwdcompare('', password_hash) = 1
UNION
SELECT NAME,
'password123' AS 'password'
FROM   sys.sql_logins
WHERE  Pwdcompare('password123', password_hash) = 1

In above query, we are trying to find:

•     Password same as user name – first query
•     Blank password – second query
•     Password = password123 – third query

These are one of the most common password used in the industry. I am sure you can extend this further by modifying it and adding more weak passwords.

Here is the sample output for the above:

Hope this article would help you in finding weak passwords and make it more complex.

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In this tutorial, I will show you how to use extended events to identify page splits in SQL Server. The easiest way to track if page splits are happening in SQL Server is to use the PerfMon Counters. For the records you can start from  “SQL Server: Access Methods -> Page Splits/sec”. This counter is quite handy to understand if this behavior happens in our SQL Server instance.

Step 1

Let us first create a database for our experiment. We will also create our Extended Event to track the PageSplits.

-- Create a dummy database
CREATE DATABASE PageSplits
GO
-- Get the DB ID, we will use it in next step
SELECT DB_ID('PageSplits')
GO
-- Create Session
CREATE EVENT SESSION [Catch_PageSplit] ON SERVER
ADD EVENT sqlserver.page_split(
WHERE ([package0].[equal_uint64]([database_id],(10))))  -- NOTE: Please make sure you change the DATABASE_ID
ADD TARGET package0.ring_buffer
WITH (MAX_MEMORY=4096 KB,EVENT_RETENTION_MODE=ALLOW_SINGLE_EVENT_LOSS,
MAX_DISPATCH_LATENCY=30 SECONDS,MAX_EVENT_SIZE=0 KB,
MEMORY_PARTITION_MODE=NONE,TRACK_CAUSALITY=OFF)
GO
-- Start the event session
ALTER EVENT SESSION [Catch_PageSplit] ON SERVER
STATE = start;
GO

Step 2

Before we get to the next step, let us start monitoring our Extended Events for any possible page splits.

USE PageSplits
GO
CREATE TABLE mytest (
myCompany CHAR(5) NOT NULL CONSTRAINT pk_mytest PRIMARY KEY CLUSTERED,
FillData VARCHAR(3000) NOT NULL
)
GO
INSERT mytest ( myCompany, FillData )
VALUES( '00001', REPLICATE( 'A', 3000 ) ),
( '00002', REPLICATE( 'B', 1000 ) ),
( '00003', REPLICATE( 'C', 3000 ) ),
( '00004', REPLICATE( 'A', 3000 ) ),
( '00005', REPLICATE( 'B', 1000 ) ),
( '00006', REPLICATE( 'C', 3000 ) ),
( '00007', REPLICATE( 'A', 3000 ) ),
( '00008', REPLICATE( 'B', 1000 ) ),
( '00009', REPLICATE( 'C', 3000 ) )
GO

Step 3

Next step is to create a table with some values. Later we will use this to create a page split scenario:

Step 4

Then, create the scenario of page split by updating a row with some extra data.

-- Update to introduce a page split
UPDATE mytest
SET FillData = REPLICATE( 'B', 3000)
WHERE myCompany = '00002'
GO

Don’t forget to look at the Live Data feed for entries. If the Page Split happen you will see something like:

As you can see, this Page Split has happened because of an Update. The two pages under question are also shown. We can also see the database ID under question that caused the page split.

Step 5

Now that we learnt something new here, let us clean up the database we just created using this code:
-- Clean up time
USE MASTER
GO
DROP DATABASE PageSplits
GO
DROP EVENT SESSION [Catch_PageSplit] ON SERVER
GO

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Here I am going to share how can you take the database backup of all the SQL Server databases at once instead of taking it individually.

First, you need to create a folder in any drive to store the backup of database which you are going to take. For example, you have to create a folder named "dbBackup" in my drive "C:\"

Then, copy the below code & paste it in your SQL Server Query Executer page:

    DECLARE @DBName varchar(255)
    DECLARE @DATABASES_Fetch int
    DECLARE DATABASES_CURSOR CURSOR FOR
        select
            DATABASE_NAME   = db_name(s_mf.database_id)
        from
            sys.master_files s_mf
        where
           -- ONLINE
            s_mf.state = 0

           -- Only look at databases to which we have access
        and has_dbaccess(db_name(s_mf.database_id)) = 1

            -- Not master, tempdb or model
        and db_name(s_mf.database_id) not in ('Master','tempdb','model')
        group by s_mf.database_id
        order by 1

    OPEN DATABASES_CURSOR

    FETCH NEXT FROM DATABASES_CURSOR INTO @DBName

    WHILE @@FETCH_STATUS = 0
    BEGIN
        declare @DBFileName varchar(256)   
        set @DBFileName = datename(dw, getdate()) + ' - ' +
                           replace(replace(@DBName,':','_'),'\','_')

        exec ('BACKUP DATABASE [' + @DBName + '] TO  DISK = N''c:\dbBackup\' +
            @DBFileName + '.bak' + ''' WITH NOFORMAT, INIT,  NAME = N''' +
            @DBName + '-Full Database Backup'', SKIP, NOREWIND, NOUNLOAD,  STATS = 100')

        FETCH NEXT FROM DATABASES_CURSOR INTO @DBName
    END

    CLOSE DATABASES_CURSOR
    DEALLOCATE DATABASES_CURSOR

Now execute the page and check your Folder "dbBackup" in Drive "C:/" . You will find all the databases backup in it.

Now, you are done! Simple, right?

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In this tutorial, I'm gonna tell you about inserting large amount of random data into sql server tables for performance testing. 

Just follow these step to create a large table with random data for performance testing:

Step 1

If Table exists drop the tables:

If (Exists (select *
            from information_schema.tables
            where table_name = 'tblProductSales'))
Begin
 Drop Table tblProductSales
End

If (Exists (select *
            from information_schema.tables
            where table_name = 'tblProducts'))
Begin
 Drop Table tblProducts
End

Step 2

Then you can recreate the tables:

Create Table tblProducts
(
 [Id] int identity primary key,
 [Name] nvarchar(50),
 [Description] nvarchar(250)
)

Create Table tblProductSales
(
 Id int primary key identity,
 ProductId int foreign key references tblProducts(Id),
 UnitPrice int,
 QuantitySold int
)

Step 3

Insert Sample data into tblProducts table

Declare @Id int
Set @Id = 1

While(@Id <= 300000)
Begin
 Insert into tblProducts values('Product - ' + CAST(@Id as nvarchar(20)),
 'Product - ' + CAST(@Id as nvarchar(20)) + ' Description')
 
 Print @Id
 Set @Id = @Id + 1
End

Step 4

Declare variables to hold a random ProductId, UnitPrice and QuantitySold

declare @RandomProductId int
declare @RandomUnitPrice int
declare @RandomQuantitySold int

Declare and set variables to generate a random ProductId between 1 and 100000

declare @UpperLimitForProductId int
declare @LowerLimitForProductId int

set @LowerLimitForProductId = 1
set @UpperLimitForProductId = 100000

Declare and set variables to generate a random UnitPrice between 1 and 100

declare @UpperLimitForUnitPrice int
declare @LowerLimitForUnitPrice int

set @LowerLimitForUnitPrice = 1
set @UpperLimitForUnitPrice = 100

Declare and set variables to generate a random QuantitySold between 1 and 10

declare @UpperLimitForQuantitySold int
declare @LowerLimitForQuantitySold int

set @LowerLimitForQuantitySold = 1
set @UpperLimitForQuantitySold = 10

Step 5

Now, you have to insert Sample data into tblProductSales table

Declare @Counter int
Set @Counter = 1

While(@Counter <= 450000)
Begin
 select @RandomProductId = Round(((@UpperLimitForProductId - @LowerLimitForProductId) * Rand() + @LowerLimitForProductId), 0)
 select @RandomUnitPrice = Round(((@UpperLimitForUnitPrice - @LowerLimitForUnitPrice) * Rand() + @LowerLimitForUnitPrice), 0)
 select @RandomQuantitySold = Round(((@UpperLimitForQuantitySold - @LowerLimitForQuantitySold) * Rand() + @LowerLimitForQuantitySold), 0)
 
 Insert into tblProductsales
 values(@RandomProductId, @RandomUnitPrice, @RandomQuantitySold)

 Print @Counter
 Set @Counter = @Counter + 1
End

Step 6

Finally, check the data in the tables using a simple SELECT query to make sure the data has been inserted as expected.
Select * from tblProducts
Select * from tblProductSales

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Indexes play an important role in SQL Server performance. Coins always have two sides, just like a well-designed index can improve query performance and an incorrect index can impact query performance. So it is important to find which indexes are not being used. It helps us to reduce storage and reduce the overhead of the database engine to maintain unused indexes. But how can we find indexes that are not being used? In this article, I'm gonna tell you how to identify unused indexes in SQL Server.

The absence of an index can result in table or index scans that reduce performance in some case and also too many indexes require extra storage and extra effort to maintain the database and it might slow down insert / update operations. One of the approaches to improve the overall performance is keep used indexes but drop all unused indexes.

"dm_db_index_physical_stats" is a dynamic management view related to index statistics. This view gives information about indexes used or unused, it complete or missing some columns is irrelevant. This dynamic view has many important columns like user_seeks (number of seeks by user queries), user_scans (number of scans by user queries), user_lookups (number of bookmark lookups by user queries) and a combination of these three columns provide us a total read count. The column user updates (number of updates by user queries) indicates the level of maintenance on the index caused by insert / update / delete operations on the table or view. A proper join among these DVM and system tables such as indexes, objects and schemas enable us to list all unused indexes for a single database.

The following query helps us to find unused indexes in our database:

    SELECT  
    o.name AS TableName, 
    i.name AS Indexname, 
    i.is_primary_key AS PrimaryKey, 
    s.user_seeks + s.user_scans + s.user_lookups AS NumOfReads, 
    s.user_updates AS NumOfWrites, 
    (SELECT SUM(p.rows) FROM sys.partitions p WHERE p.index_id = s.index_id AND s.object_id = p.object_id) AS TableRows, 
    'DROP INDEX ' + QUOTENAME(i.name) + ' ON ' + QUOTENAME(c.name) + '.' + QUOTENAME(OBJECT_NAME(s.object_id)) AS 'DropStatement' 
    FROM sys.dm_db_index_usage_stats s  
    INNER JOIN sys.indexes i ON i.index_id = s.index_id AND s.object_id = i.object_id  
    INNER JOIN sys.objects o ON s.object_id = o.object_id 
    INNER JOIN sys.schemAS c ON o.schema_id = c.schema_id 
    WHERE OBJECTPROPERTY(s.object_id,'IsUserTable') = 1 
    AND s.databASe_id = DB_ID()  
    AND i.type_desc = 'NONCLUSTERED' 
    AND i.is_primary_key = 0 
    AND i.is_unique_constraint = 0 

The preceding query includes the following helpful information.

•     Table name
•     Index name
•     Primary key
•     Number of read count
•     Number of writes
•     Total number of rows
•     Drop statement

The following  is the output of the preceding query:

After running the preceding query for the database it will list all the non-clustered indexes for all tables. Now we can determine the unused indexes by comparing the number of reads applied to an index with the number of writes. If we have a number of reads (NumOfReads column in the preceding query) then the indexes are not being used.

Base on the query result and application knowledge, we may decide which index needs to be dropped and the last column of the query contains a drop index statement.

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You know that RAND() function in SQL Server generates a random float value 0 through 1 (excluding 0 and 1). In this article, I will show you how to generate different random number for each group using RAND() Function.

First, let's us create the following dataset:

CREATE TABLE #random(no INT)
INSERT INTO #random(no)
SELECT 1 UNION ALL
SELECT 1 UNION ALL
SELECT 1 UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 3

If you want to generate a random value, you can use the following code:

SELECT no, RAND() AS random_number FROM #random

This code will result to:
no random_number
 1 0.370366365964781
 1 0.370366365964781
 1 0.370366365964781
 2 0.370366365964781
 3 0.370366365964781
 3 0.370366365964781

Please note that when you execute it , you may get different random number than what I got for column 2 but all will be same. What if you want to generate random number in such a way that it is reset to each column value (in this case the column is no)? Did you know that RAND() accepts a seed value as well?

If you execute the following code:

SELECT no, RAND() AS random_number,RAND(no) AS random_number_reset FROM #random

Then, it will comes to the result:
no random_number random_number_reset
 1 0.58334760467751 0.713591993212924
 1 0.58334760467751 0.713591993212924
 1 0.58334760467751 0.713591993212924
 2 0.58334760467751 0.713610626184182
 3 0.58334760467751 0.71362925915544
 3 0.58334760467751 0.71362925915544

Please note that when you execute it , you may get different random number than what I got for column2 2 and 3. If you notice the result the values of second column is same for all rows, whereas the values of third column is same withing a group (column no), and different across groups. So if you want to generate random number differently for each group, you can make use of this method.

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