Nullables in Free Pascal and Delphi

Submitted by st on Wed, 30/01/2013 - 00:44

An example of generic implementation of nullable value types in FreePascal (easy to adapt for Delphi).

Programming

Delphi |
Free Pascal

Fast inserting a file into a table

Submitted by st on Sat, 01/12/2012 - 11:15

How to insert fast a file (i.e. binary one) from disk to a SQL Server table?

Certainly the SQL Server account should have a corresponding permissions to access the file on the disk. For example I take the file C:\WINDOWS\system32\oembios.bin having the size about 12 MB. For really big files you'd better switch to the FILESTREAM approach.

Programming

SQL Server

SQL: generate date/time series

Submitted by st on Fri, 27/04/2012 - 20:31

There are many examples of user defined table functions generating the series of dates(times) between two specified values. Usually, in OLAP you can see a table filled by the date/time series, too. Such table avoid to generate the values "on the fly".

However, in some cases you may be unable to use an UDF or a table. Fortunately, "pure SQL" method still works.

Suppose, the start and finish dates are specified as entry parameters. The transact SQL code below generates the series "moth by month".

Programming

SQL: delete duplicated rows

Submitted by st on Fri, 09/03/2012 - 16:17

How to delete the rows having the duplicated values of one or more columns and considered as duplicates? The example in Transact SQL is below.

Programming

SQL Server

Transact SQL: exporting table or view in CSV

Submitted by st on Mon, 20/02/2012 - 12:38

It's pretty easy on SQL Server but pay attention to the database/server rights of used connection. Usually, the preparing like sp_configure requires a system administrator privileges.

Programming

SQL Server

DateTime in C++

Submitted by st on Sat, 04/12/2010 - 13:48

Many years ago we had a need to manipulate the data of types "date" and "time" (DateTime in C# and Delphi/C++Builder). I had developed the corresponding class for these purposes.

Here is the interface with comments:

Programming

GUI: evolution of descriptions

Submitted by st on Thu, 02/12/2010 - 11:37

Let's see one simple example showing how the methods and the languages of graphical user interface (GUI) description are progressing (or regressing, it depends) during the last 15-20 years.

The primitive form description requires:

Indexing columns of bit type

Submitted by st on Wed, 24/11/2010 - 20:06

Clearly, an index build on only one column of the bit type is useless because the selectivity is poor (50% of a table in average). However, when a table has several columns of the bit type, the composite index may be efficient.

For the test example, we'll create a table and fill it with random data.

Programming

SQL Server

Dynamic filtering with SQL

Submitted by st on Mon, 15/11/2010 - 18:45

The one of the most frequent asked question in database development is "How to filter the data returned by a query according to some user selected criteria?". To complete the solution with dynamic ordering see my other blog post.

For every method template I will add icons indicating corresponding advantages and drawbacks.

SQL Server

Dynamic result ordering in SQL

Submitted by st on Tue, 18/05/2010 - 17:19

There are several methods to implement the dynamic ordering of result returned by SQL query. The examples of stored procedures below use the Microsoft's demo database AdventureWorks.

USE AdventureWorks
GO

Programming

SQL Server

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