code 128 checksum c# Writing the search procedure in Visual C#.NET

Generator Code128 in Visual C#.NET Writing the search procedure

Writing the search procedure
Code-128 Creator In Visual C#.NET
Using Barcode drawer for .NET Control to generate, create Code 128 Code Set C image in VS .NET applications.
www.OnBarcode.com
Recognizing Code 128 Code Set C In Visual C#.NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Although the principle for the table should be fairly easy to grasp, writing a search procedure that uses it is not as trivial as it may seem. I went through some trial and error, until I arrived at a good solution. Before I go on, I should say that to keep things simple I ignore the possibility that the search string may include wildcards like % or _, as well as range patterns like [a-d]
Printing 2D Barcode In C#
Using Barcode generation for Visual Studio .NET Control to generate, create Matrix image in .NET framework applications.
www.OnBarcode.com
Code 128C Printer In C#.NET
Using Barcode encoder for .NET Control to generate, create Code 128A image in Visual Studio .NET applications.
www.OnBarcode.com
Fragments and persons
Draw Barcode In C#.NET
Using Barcode creation for .NET framework Control to generate, create Barcode image in .NET framework applications.
www.OnBarcode.com
Drawing USS-128 In C#.NET
Using Barcode generator for .NET framework Control to generate, create EAN / UCC - 13 image in VS .NET applications.
www.OnBarcode.com
or [^a-d]. The best place to deal with these would probably be in the wordfragments function. To handle range patterns correctly would probably call for an implementation in the CLR.
QR Generation In Visual C#.NET
Using Barcode printer for .NET Control to generate, create QR Code JIS X 0510 image in VS .NET applications.
www.OnBarcode.com
ISSN - 10 Creation In C#.NET
Using Barcode maker for VS .NET Control to generate, create ISSN - 13 image in VS .NET applications.
www.OnBarcode.com
THE QUEST
Scan Code 128 Code Set A In VB.NET
Using Barcode reader for Visual Studio .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Create Code 128 Code Set C In Objective-C
Using Barcode creator for iPhone Control to generate, create Code 128 Code Set B image in iPhone applications.
www.OnBarcode.com
The first issue I ran into was that the optimizer tried to use the index on the email column as the starting point, which entirely nullified the purpose of the new table. Thankfully, I found a simple solution. I replaced the LIKE expression with the logical equivalent as follows:
Create UCC - 12 In Objective-C
Using Barcode printer for iPhone Control to generate, create EAN128 image in iPhone applications.
www.OnBarcode.com
Scan QR Code 2d Barcode In Visual C#
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
WHERE patindex('%' + @wild + '%', email) > 0
Barcode Scanner In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Code 128B Encoder In Java
Using Barcode generator for Java Control to generate, create Code-128 image in Java applications.
www.OnBarcode.com
By wrapping the column in an expression, I prevented SQL Server from considering the index on the column. My next mistake was that I used the patindex expression as soon as an email address matched any fragment from the search string. This was not good at all, when the search string was a .com address. When I gave it new thought, it seemed logical to find the persons for which the email address included all the fragments of the search string. But this too proved to be expensive with a .com address. The query I wrote had to read all rows in fragments_persons for the fragments .co and com.
ECC200 Creation In Java
Using Barcode generator for Java Control to generate, create Data Matrix image in Java applications.
www.OnBarcode.com
Universal Product Code Version A Generation In Java
Using Barcode maker for Java Control to generate, create Universal Product Code version A image in Java applications.
www.OnBarcode.com
ENTER STATISTICS
Generating Code 128 Code Set B In Java
Using Barcode encoder for Android Control to generate, create Code 128A image in Android applications.
www.OnBarcode.com
Code128 Creator In Visual Basic .NET
Using Barcode generator for VS .NET Control to generate, create Code 128 Code Set A image in VS .NET applications.
www.OnBarcode.com
I then said to myself: what if I look for the least common fragment of the search string To be able to determine which fragment this is, I introduced a second table as follows:
Barcode Printer In Java
Using Barcode encoder for Android Control to generate, create Barcode image in Android applications.
www.OnBarcode.com
Printing ANSI/AIM Code 128 In None
Using Barcode drawer for Software Control to generate, create Code 128C image in Software applications.
www.OnBarcode.com
CREATE TABLE fragments_statistics (fragment char(3) NOT NULL, cnt int NOT NULL, CONSTRAINT pk_fragments_statistics PRIMARY KEY (fragment) )
The script 03_fragments_persons.sql creates this table, and the stored procedure load_fragments_persons loads the table in a straightforward way:
INSERT fragments_statistics(fragment, cnt) SELECT fragment, COUNT(*) FROM fragments_persons GROUP BY fragment
Not only do we have our own index, we now also have our own statistics! Equipped with this table, I finally made progress, but I was still not satisfied with the performance for the test string omamo@petinosemdesetletnicah.com. When data was on disk, this search took over 4 seconds, which can be explained by the fact that the least common fragment in this string maps to 2851 persons.
THE FINAL ANSWER
I did one final adjustment: look for persons that match both of the two least common fragments in the search string. Listing 2 shows the procedure I finally arrived at.
Build your own index
Listing 2
The procedure map_search_five
CREATE PROCEDURE map_search_five @wild varchar(80) AS DECLARE @frag1 char(3), @frag2 char(3) ; WITH numbered_frags AS ( SELECT fragment, rowno = row_number() OVER(ORDER BY cnt) FROM fragments_statistics WHERE fragment IN (SELECT frag FROM wordfragments(@wild)) ) SELECT @frag1 = MIN(fragment), @frag2 = MAX(fragment) FROM numbered_frags WHERE rowno <= 2 SELECT FROM WHERE AND person_id, first_name, last_name, birth_date, email persons p patindex('%' + @wild + '%', email) > 0 EXISTS (SELECT * FROM fragments_persons fp WHERE fp.person_id = p.person_id AND fp.fragment = @frag1) EXISTS (SELECT * FROM fragments_persons fp WHERE fp.person_id = p.person_id AND fp.fragment = @frag2)
The common table expression (CTE) numbered_frags ranks the fragments by their frequency. The condition rowno <= 2 extracts the two least common fragments, and with the help of MIN and MAX, we get them into variables. When we have the variables, we run the actual search query. You may think that a single EXISTS clause with a condition of IN (@frag1, @frag2) would suffice. I tried this, but I got a table scan in the fragments_persons table, where there are two separate EXISTS clauses. When I ran map_search_five through tester_sp, I got this result:
Disk Cache joy 373 16 aam 260 16 niska 4936 203 omamo@ 306 140
The performance is good. It still takes 5 seconds to search niska from disk, but for 2,000 hits, this should be acceptable. Nevertheless, there are still some problematic strings. For instance the string coma matches only 17 persons, but it takes over 10 seconds to return these, as both the strings com and oma are common in the material. You find the script for map_search_five in the file 04_map_search.sql. This file also includes my first four less successful attempts. If you decide to look at, say, the three least common fragments, you can use a procedure that is more extensible called map_search_six, which uses a different technique to find the least two common fragments.
Copyright © OnBarcode.com . All rights reserved.