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SQL Server 2012 Hosting Belgium - HostForLIFE.eu :: How to Fix Distribution setup SQL Server Agent error: "RegCreateKeyEx() returned error 5, 'Access is denied.'" ?

clock October 15, 2019 12:15 by author Peter

With this short article, I will tell you about How to Fix Distribution setup SQL Server Agent error: "RegCreateKeyEx() returned error 5, 'Access is denied.'" on my SQL Server 2012 Hosting.

In the Configure Distribution Wizard, the step "Configuring SQL Server Agent to start automatically" errors with the following text:

TITLE: Configure Distribution Wizard
------------------------------
An error occurred configuring SQL Server Agent.
------------------------------
ADDITIONAL INFORMATION:
RegCreateKeyEx() returned error 5, 'Access is denied.' (Microsoft SQL Server, Error: 22002)

This is a very minor error, and not difficult to work around at all. The wizard is making an attempt to alter the SQL Server Agent service "Start Mode" to Automatic. you'll be able to try this via the SQL Server Configuration Manager instead.

In the Sysinternals method Monitor, you'll see: Operation: RegCreateKey Result: ACCESS DENIED Path: "HKLM\System\CurrentControlSet\Services\SQLAgent$SQL2012"

 

If you encounter this error, choose "No" in the "SQL Server Agent Start" page in the configure Distribution Wizard (as shown below), so set your agent service to Automatic start Mode via the SQL Server Configuration Manager.

The third step of the wizard that failed before won't happen. Why the failure truly happens I didn't figure this out, and i am open to feedback, however this seems like a vestigial step to a wizard that otherwise has no negative impact. Running SSMS with "run as Administrator" doesn't seem to fix this error either. i would like to recognize why this error happens within the 1st place.

HostForLIFE.eu SQL Server 2012 Hosting
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SQL Server 2019 Hosting - HostForLIFE.eu :: Enforcing Foreign Key Constraint In A Multi-Valued Column In SQL Server

clock October 4, 2019 09:04 by author Peter

I have seen that sometimes, a few developers create a multi-valued column to store more than one value in a comma-separated manner (like 1,3,4) and then, they read the individual values by splitting using comma.

However, due to such design, they can't add a foreign key constraint like below.

  • ALTER TABLE <Table-name> 
  • ADD CONSTRAINT <FK-Name> FOREIGN KEY (<col-name>) REFERENCES <Lookup Table-name>(<Lookup col-name>); 

PS - Personally, I am not a fan of such design and I would recommend having a mapping table in such cases; however, at times, mostly on the existing system, you don't have the choice to rewrite or change the design and hence finding a quick fix is the only option.
 
To illustrate the problem and solution, let's take an example of two tables - Employee and Country - as below.
    CREATE TABLE Country ( 
       Id INT NOT NULL PRIMARY KEY, 
       Name varchar(100) NOT NULL, 
       Code varchar(50) NULL 
    ); 
      
    CREATE TABLE Employee ( 
       Id INT NOT NULL PRIMARY KEY, 
       HomeCountryId INT NOT NULL, 
       VisitedCountryIds varchar(200) NULL, 
       Constraint FK_Employee_Country FOREIGN KEY (HomeCountryId) REFERENCES Country(Id) 
    ); 


Let's assume the country id as 1, 2 till 249 (As per the latest data available during the time of writing the post).
 
As you can see there is FK constraint on the HomeCountryId, hence only valid Country Id (from 1-249) can be entered; however, in the field VisitedCountryIds, there is no check and any id (like 250, 251, etc.) can also be added even if it doesn't exist in the country table. Well, this can lead to the data integrity issue.
 
So how we can make sure that users can only enter valid country ids (from 1-249) in the VisitedCountryIds column?
 
The fix is two-fold as following.
 
Create the function in the SQL Server as below.
    CREATE FUNCTION [dbo].[svf_CheckCountryIds](@CountryIds nvarchar(200)) 
    RETURNS bit AS 
    BEGIN 
    declare @valid bit 
    declare @rowsInserted INT 
    declare @addedCountryIds table([CountryId] nvarchar(200)) 
     
    insert into @addedCountryIds 
    select value from STRING_SPLIT(@CountryIds, ',') 
    set @rowsInserted = @@rowcount 
     
    if (@rowsInserted = (select count(a.CountryId) from @addedCountryIds a join [Country] b on a.CountryId = b.Id)) 
    begin 
    set @valid = 1 
    end 
    else 
    begin 
    set @valid = 0 
    end 
     
    RETURN @valid 
    END 


As you can see in the above function, we are passing the column data that is in the comma concatenated form and then they are split using STRING_SPLIT function and stored in the addedCountryIds table variable. Also, the inserted row count is stored in the rowsInserted variable.
 
Later, the values on addedCountryIds arejoined with Country table and if the count is matching, i.e., if all the passed country id is present in the Country table, true/1 is returned else false/0 is returned.
 
Create the FK with check constraint on the VisitedCountryIds as follows,
    ALTER TABLE Employee 
    ADD CONSTRAINT [FK_Employee_VisitedCountryIds] CHECK ([dbo].[svf_CheckCountryIds]([VisitedCountryIds]) = 1) 


As you can see constraint FK_Employee_VisitedCountryIds is created on VisitedCountryIds with condition that function svf_CheckCountryIds should return value as 1/true.
Now when you enter any country id other than 1 to 249, for example, if you enter VisitedCountryIds as '103,236,250', an error will be thrown as follows as id 250 is not the part of the country id list.
 
Msg 547, Level 16, State 0, Line 4
The INSERT statement conflicted with the CHECK constraint "FK_Employee_VisitedCountryIds". The conflict occurred in database "TestDb", table "dbo.Employee", column 'VisitedCountryIds'.
The statement has been terminated.
 
However, if you enter VisitedCountryIds as '103,236,249', it will be successfully inserted because all the ids are part of the country list.
 
I hope you found this post useful in handling the foreign keys in multivalued columns. Looking forward to your comments.



SQL Server Hosting - HostForLIFE.eu :: How To Find Running Total And Final Total In SQL Server?

clock September 11, 2019 10:04 by author Peter

Here, we will explain how to find Running Total and Final Total or Grand Total in SQL Server. For example, you have the below given #tblEmployee temporary table and has the data, as shown below.

    CREATE TABLE #tblEmployee 
    ( 
       EmpID int identity, 
       Salary Decimal(8,2), 
       Grade varchar(10) 
    ) 


Insert some values in a temporary table like this.
    INSERT INTO #tblEmployee(Salary,Grade) Values(10000.51,'B') 
    INSERT INTO #tblEmployee(Salary,Grade) Values(20000.12,'B') 
    INSERT INTO #tblEmployee(Salary,Grade) Values(25000.02,'B') 
    INSERT INTO #tblEmployee(Salary,Grade) Values(9000.28,'C') 
    INSERT INTO #tblEmployee(Salary,Grade) Values(7000,'C') 
    INSERT INTO #tblEmployee(Salary,Grade) Values(6000,'C') 


Find the Running Total in the SQL Server

Write the following SQL Query to find the running total for the Salary column from #tblEmployee temporary table.
SELECT EmpID, Grade, Emp.Salary ,(SELECT SUM(Salary) FROM #tblEmployee WHERE EmpID <= Emp.EmpID) 'Running Total' FROM #tblEmployee Emp 
I have used the sub-query to find the running total.
 
Find the Final Total or Grand Total in SQL Server
 Write the following SQL Query to find the final total or grand total for the Salary column from #tblEmployee temporary table.
    SELECT EmpID, SUM(Salary) AS Salary FROM #tblEmployee GROUP BY EmpID WITH ROLLUP 

Here I used ROLLUP to achieve the desired result.
 
What is ROLLUP
The ROLLUP is an extension of the GROUP BY clause. The ROLLUP option allows you to include extra rows that represent the subtotals, which are commonly referred to as super-aggregate rows, along with the grand total row. By using the ROLLUP option, you can use a single query to generate multiple grouping sets.
 
Following Result produce by this SQL Query,

So, in this blog, we tried to explain how to find the running total from the SQL table. I hope this blog helps all of us. It is also most asked question from the interview.

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SQL Server Hosting - HostForLIFE.eu :: Instead Of Triggers

clock September 4, 2019 12:41 by author Peter

Instead of triggers are used to skip DML commands. They fire when you try to execute insert, update or delete statement but instead of executing these commands trigger actually works and trigger functionality executes.
 

Example
    create table approved_emp ( eid int identity(1,1), ename varchar(30)) 
    create table emp ( id int identity(1,1) , ename varchar(30), AddedBy varchar(30)) 
      
    Create trigger instead_of on approved_emp 
    instead of insert 
    as 
    begin 
    declare @name varchar(30) 
    select @name=ename from inserted 
    insert into temp_audit values(@name, USER ) 
    end 


So, basically, trigger will work as, when we will try to add new record in approved_emp table, instead of inserting new records it will add ename into emp table. No data will reflect in approved_emp table as trigger is fired on the table every time while adding data into that table.
 
You can also create instead of triggers for update and delete as well.
 



SQL Server 2019 Hosting - HostForLIFE.eu :: Store Multiple NULL Values With Unique Data In SQL Server

clock August 30, 2019 12:01 by author Peter

Sometimes, we get data that needs to be unique but we can also get NULL records. Existing ways to achieve uniqueness don’t allow NULLs (Primary Key) or allow a maximum of one NULL (Unique Constraint).
 
Let’s take an example to understand this better. Suppose, you have an Employee table with fields like Id, FirstName, MiddleName, LastName, Email, etc. As per the requirement, the email needs to be unique (if supplied), however, users are also allowed to register without entering their email and hence in the database Email is a nullable field.
 
So, how would you achieve the Email uniqueness having more than one NULL?

    CREATE UNIQUE NONCLUSTERED INDEX [UX_Employee_Email] ON [dbo].Employee WHERE Email IS NOT NULL 

The above code will ensure that the Email doesn’t have duplicate data, however, it may store more than one NULL.

 



SQL Server 2016 Hosting - HostForLIFE.eu :: SQL Server Full Text Search with rank values

clock August 28, 2019 12:51 by author Peter

OnceSQL Server Full-Text Search with rank values  I wrote a post titled enabling Fulltext search in Azure SQL database discussing Full-Text search in Azure. while using it with one of my databases, needed to show the result of the search ordered by however well they match to the search criteria. in order to sort the result as i need, the best is, get a rank generated for every row and use it for ordering the result. I had used Freetext operate for obtaining the result but if i realized that this can not be achieved using the Freetext function.

The CONTAINSTABLE and FREETEXTTABLE functions return a column named Rank for showing the rank related to the record based on matching. this can be used get the result sorted based on it, showing most relevant records at the top. Remember, the higher value of the Rank generated indicates the best matching.

Now, write the following code:
view plainprint?

    -- Creating a table  
    CREATE TABLE dbo.EmployeeDetails  
    (  
     EmployeeDetailsId int identity(1,1) not null  
     , constraint pk_EmployeeDetails primary key (EmployeeDetailsId)  
     , WorkingExperience nvarchar(4000) not null  
     , ProjectsWorked nvarchar(4000) not null  
     , Resume nvarchar(max)   
    )  
    GO  
      
    CREATE FULLTEXT CATALOG EmployeeCatelog;  
    GO  
      
    CREATE FULLTEXT INDEX ON dbo.EmployeeDetails   
     (WorkingExperience, ProjectsWorked, Resume) KEY INDEX pk_EmployeeDetails  
     ON EmployeeCatelog;  
     -- By default CHANGE_TRACKING = AUTO  
      
      
    -- Once enabled, search can be performed;  
    SELECT *  
    FROM dbo.EmployeeDetails  
    WHERE freetext ((WorkingExperience, ProjectsWorked, Resume), 'SQL');  
      
    SELECT *  
    FROM dbo.EmployeeDetails  
    WHERE freetext ((Resume), 'SQL');  
      
    -- Get the rank and sort the result using it  
    SELECT t.Rank, e.*  
    FROM dbo.EmployeeDetails e  
     INNER JOIN CONTAINSTABLE (dbo.EmployeeDetails, (WorkingExperience, ProjectsWorked, Resume), 'SQL') AS t  
      ON e.EmployeeDetailsId = t.[Key]  
    ORDER BY t.Rank DESC  

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SQL Server 2016 Hosting - HostForLIFE.eu :: Execute SQL Query In String Format

clock August 23, 2019 11:11 by author Peter

There are times when we need to pass a SQL query as a string that has been created dynamically and execute it on database or from the code. For this purpose, we can use a built-in stored procedure, sp_executesql.

Stored procedure, sp_executesql executes a SQL statement or batch that can be reused many times, or one that has been built dynamically.

Here is the syntax:
sp_executesql [ @stmt = ] statement 

{ , [ @params = ] N'@parameter_name data_type [ OUT | OUTPUT ][ ,...n ]' } 
{ , [ @param1 = ] 'value1' [ ,...n ] } 


Here is an example where SQL is compiled as a string, str1. The SELECT SQL statement is executed via the string parameter passed to the sp_executesql.
declare @str1 nvarchar(200) -----declare a variable 
set @str1='SELECT * FROM tablename' --- set your query to variable 
exec sp_executesql @str1 



SQL Server 2019 Hosting - HostForLIFE.eu :: How To Find Indian Financial Year And Financial Quarter From A Particular Date In SQL?

clock August 7, 2019 12:15 by author Peter

Here we will explain how to find the Indian financial year and financial quarter in a particular date with an example in SQL Server.  I have used the CASE statement and DATEPART() function to achieve this requirement.

DATEPART() in SQL Server
The DATEPART() function returns a specified part of a date, like – year, month, day, hour, minute, etc.

CASE Statement in SQL Server
CASE is the extension of IF ... ELSE statement. So, once a condition is true, it will stop reading & return the result. If no conditions are true, it returns the value in the ELSE block.
 
A) Find the FINANCIAL YEAR from date
 Write the below-given SQL code to find the financial year from given particular date,
    DECLARE@FilterDateASDATETIME 
    SET@FilterDate = GETDATE() 
    SELECTCASEWHENDATEPART(QUARTER,@FilterDate)= 1 THENYEAR(@FilterDate)ELSEYEAR(@FilterDate)+ 1 ENDAS[FINANCIAL_YEAR] 
    ** Note - @FilterDate - The date to be find the financial year


Output
Following is the result of the SQL query for financial year,

 
B) Find the FINANCIAL QUARTER from date
 
Write the below SQL code to find the financial Quarter from given particular date,
    DECLARE@FilterDateASDATETIME 
    SET@FilterDate = GETDATE() 
    SELECTCASEDATEPART(QUARTER, @FilterDate)WHEN 1 THEN'Q4'WHEN 2 THEN'Q1'WHEN 3 THEN'Q2'WHEN 4 THEN'Q3'ENDAS[FINANCIAL_QUARTER] 
    ** Note - @FilterDate - The date to be find the financial Quarter


Output
Following is the result of the SQL query for the financial quarter,



SQL Server 2012 Hosting - HostForLIFE.eu :: SQL Queries for Database Analysis

clock August 2, 2019 12:03 by author Peter

In this post, I'll share few useful SQL queries for database analysis on SQL Server 2012. I shared few SQL queries useful in analyzing database, which I use quite often. This query will return all table names and no.of rows in it for built-in tables.

    -- List all table names and number of rows in it for user-defined tables 
    SELECT distinct t.name,prt.rows 
    FROM sys.tables t INNER JOIN sys.partitions AS prt 
    ON t.object_id = prt.object_id where t.is_ms_shipped=1 -- 0 for user-defined tables 
    order by prt.rows desc 


This query will return column names and its data type of a table.
    -- Get column names and its types of a table 
    SELECT cols.name,t.name 
    FROM sys.objects o join sys.columns cols on o.object_id= cols.object_id 
    join sys.types t on t.system_type_id=cols.system_type_id 
    and o.name='Employee'-- Table Name


This query will return file name, its size and file group name of a database.
    SELECT sdf.name AS [FileName], 
    size/128 AS [Size], 
    fg.name AS [File_Group_Name] 
    FROM sys.database_files sdf 
    INNER JOIN 
    sys.filegroups fg 
    ON sdf.data_space_id=fg.data_space_id 


Batch file to execute all sql files in a directory, Save it as .bat in a folder that have sql script files to be executed.
    @Echo Off 
    FOR /f %%i IN ('DIR *.Sql /B') do call :RunSql %%i 
    GOTO :END 
    :RunSql 
    Echo Executing SQL: %1 
    SQLCMD -S server1 -U user1 -P pwd1 -d DB1 -i %1 
    Echo Completed SQL: %1 
    :END 


This query will return all table names that have a Foreign key:
    SELECT SCHEMA_NAME(schema_id) AS SchemaName, 
    name AS TableName 
    FROM sys.tables where OBJECTPROPERTY(OBJECT_ID,'TableHasForeignKey') = 1 -- Return all

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SQL Server Hosting - HostForLIFE.eu :: Rename SQL Server Database

clock July 24, 2019 12:47 by author Peter

Database Administrators usually use the sp_renamedb system stored procedure to quickly rename a SQL Server Database. However, the drawback of using sp_renamedb is that it doesn't rename the Logical and Physical names of the underlying database files. It's a best practice to make sure the Logical Name and Physical File Name of the database is also renamed to reflect the actual name of the database to avoid any confusion with backup, restore or detach/attach operations.

Let's first create a new database named CoreDB using the T-SQL below:

USE master
GO
IF EXISTS (SELECT name FROM sys.databases WHERE name = N'CoreDB')
DROP DATABASE CoreDB
GO
USE master
GO
CREATE DATABASE [CoreDB]
ON PRIMARY
(
NAME = N'CoreDB',
FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\CoreDB.mdf' ,
SIZE = 2048KB ,
FILEGROWTH = 1024KB
)
LOG ON
(
NAME = N'CoreDB_log',
FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\CoreDB_log.ldf' ,
SIZE = 1024KB ,
FILEGROWTH = 10%
)
GO

Rename CoreDB Database Using sp_renamedb System Stored Procedure

Now let's rename the CoreDB database to ProductsDB by executing the below T-SQL code.

USE master
GO
ALTER DATABASE CoreDB
SET SINGLE_USER

WITH ROLLBACK IMMEDIATE
GO
EXEC master..sp_renamedb 'CoreDB','ProductsDB'
GO
ALTER DATABASE ProductsDB
SET MULTI_USER
GO

Once the above T-SQL has executed successfully the database name will change however the Logical Name and File Name will not change. You can verify this by executing the T-SQL below:

USE master
GO
/* Identify Database File Names */
SELECT

name AS [Logical Name],
physical_name AS [DB File Path],
type_desc AS [File Type],
state_desc AS [State]
FROM sys.master_files
WHERE database_id = DB_ID(N'ProductsDB')
GO

Your output should look something like this from the above query.

You can see in the above snippet that the Logical Name and File Name in the DB File Path column for ProductsDB are still reflecting the old name of CoreDB. This is not a good practice to follow in a Production Environment. Below you will see the steps which a DBA can follow to rename the database and its respective files.

Steps to Rename a SQL Server Database

DBAs should follow the below steps which will not only rename the database, but at the same time will also rename the Logical Name and File Name of the database.

This first set of commands put the database in single user mode and also modifies the logical names.


/* Set Database as a Single User */
ALTER DATABASE CoreDB SET SINGLE_USER WITH ROLLBACK IMMEDIATE
/* Change Logical File Name */
ALTER DATABASE [CoreDB] MODIFY FILE (NAME=N'CoreDB', NEWNAME=N'ProductsDB')
GO
ALTER DATABASE [CoreDB] MODIFY FILE (NAME=N'CoreDB_log', NEWNAME=N'ProductsDB_log')
GO

This is the output from the above code.


Now we need to detach the database, so we can rename the physical files.  If the database files are open you will not be able to rename the files.

/* Detach Current Database */
USE [master]
GO
EXEC master.dbo.sp_detach_db @dbname = N'CoreDB'
GO

Once the CoreDB database is detached successfully then the next step will be to rename the Physical Files. This can be done either manually or by using the xp_cmdshell system stored procedure. You can enable xp_cmdshell feature using the sp_configure system stored procedure.

USE master
GO
sp_configure 'show advanced options'
GO
/* 0 = Disabled , 1 = Enabled */
sp_configure 'xp_cmdshell', 1
GO
RECONFIGURE WITH OVERRIDE
GO

Once xp_cmdshell is enabled you can use the below script to rename the physical files of the database.

/* Rename Physical Files */
USE [master]
GO
EXEC xp_cmdshell 'RENAME "C:\Program Files\Microsoft SQL ServerMSSQL10.SQL2008\
MSSQL\DATA\CoreDB.mdf", "ProductsDB.mdf"'
GO
EXEC xp_cmdshell 'RENAME "C:\Program Files\Microsoft SQL ServerMSSQL10.SQL2008\
MSSQL\DATA\CoreDB_log.ldf", "ProductsDB_log.ldf"'
GO

Once the above step has successfully executed then the next step will be to attach the database, this can be done by executing the T-SQL below:

/* Attach Renamed ProductsDB Database Online */
USE [master]
GO
CREATE DATABASE ProductsDB ON
( FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\ProductsDB.mdf' ),
( FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\ProductsDB_log.ldf' )
FOR ATTACH
GO

Once the above step has successfully executed then the final step will be to allow multi user access for the user database by executing the below T-SQL:

/* Set Database to Multi User*/
ALTER DATABASE ProductsDB SET MULTI_USER
GO

You can verify the Logical and File Names for the ProductsDB database by executing the T-SQL below:

USE master
GO
/* Identify Database File Names */
SELECT
name AS [Logical Name],
physical_name AS [DB File Path],
type_desc AS [File Type],
state_desc AS [State]
FROM sys.master_files
WHERE database_id = DB_ID(N'ProductsDB')

 

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About HostForLIFE.eu

HostForLIFE.eu is European Windows Hosting Provider which focuses on Windows Platform only. We deliver on-demand hosting solutions including Shared hosting, Reseller Hosting, Cloud Hosting, Dedicated Servers, and IT as a Service for companies of all sizes.

We have offered the latest Windows 2016 Hosting, ASP.NET Core 2.2.1 Hosting, ASP.NET MVC 6 Hosting and SQL 2017 Hosting.


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