Nik's Technology Blog

Travels through programming, networks, and computers

Resolving ADSL Synchronisation Set-up Problems

After installing ADSL recently I encountered several problems getting my USB Alcatel Modem to synchronise on the line. I tried everything, or so I thought...

After changing ADSL filters and phone cables from my USB modem to the phone socket I still was unable to get the little green LED on the front of the modem not to blink. According to the manual this synchronisation LED should switch from blinking to a solid green after booting the machine. However there was either a problem with my phone line or a problem between my master phone socket and BT's exchange.

I phoned my ISP and after confirming everything I had done he had run out of ideas for me to try. Before calling BT and fork out £60 on a call-out charge I thought I'd check the phone extension that extends the master socket upstairs. I unplugged the upstairs phone and tried synchronising.

BOOOM!...It worked!

I tried plugging in a different phone upstairs, but still the same problem. So it can't be the phone I thought. It must be the extension cable. Since ASDL runs at high frequencies a bad termination of the phone socket upstairs must be to blame for the problem, perhaps causing the signal to reflect and cause interference on the line.

So for now we can either have an upstairs phone or an ADSL connection. Oh well... one phone isn't so bad!

T-SQL to MySQL Conversions

I've been converting my live web statistics page to PHP and MySQL and after spending a while trying to find MySQL alternatives to Transact SQL (T-SQL) only SQL statements, I thought I'd share a few common solutions to the problems I eventually managed to solve.

Microsoft developers commonly use TOP in a select statement to select the first n rows from a table. The MySQL equivalent is LIMIT, which is superior in that you can specify what row to start on and well as how many to retrieve.

SELECT TOP 20 * FROM MY_TABLE

SELECT * FROM MY_TABLE LIMIT 0,20

Other problems arise from T_SQL's use of Visual Basic (VB). So statements using LCASE, UCASE, INSTR and MID won't work. MySQL of course has alternatives...

SELECT LOWER(name) FROM MY_TABLE

SELECT UPPER(name) FROM MY_TABLE

The SUBSTRING MySQL statement is equivalent to MID or LEFT if you start at the first character. The following statement would result in abcd.

SELECT SUBSTRING('abcdefghijklmnopqrstuvwxyz',1,4)

VB's INSTR is another useful function in T-SQL, the MySQL equivalent is LOCATE. Like INSTR you define a starting point in which you would like to start searching within the string. The following SQL statement would result in 4.

SELECT LOCATE('d','abcdefghijklmnopqrstuvwxyz',1)

MySQL's version of T-SQL's LEN function works in exactly the same manor, only it's called LENGTH. The following statement will result in 26.

SELECT LENGTH('abcdefghijklmnopqrstuvwxyz')

MySQL Manual - String Functions

CompTIA A+ Certification

The CompTIA A+ Certification is designed for PC technicians and PC support staff and is designed to test knowledge of computer installation, configuring and upgrading as well as system diagnostics and troubleshooting. The exam covers computer hardware and operating systems, including basic networking and maintenance skills.

220-231 and 220 232 Exams to Retire

As of November 26th 2003 CompTIA new 2003 objectives come into action and the old 2001 220-231 / 220 232 exams will be retired. However if you have taken one of the two exams required for the A+ Certification using the old 2001 syllabus, this WILL still count towards your certification.

The new 2003 objectives incorporate new hardware and operating systems that have come on the market since the last syllabus, including new types of memory, peripherals, wireless networking, Windows ME and XP.

The A+ exam like other IT Certifications is tested through Prometric or VUE testing centres at a cost of between $93 and $225. Exams are approximately 90 minutes long and are available to take in five languages, Japanese, Spanish, French and German as well as English. The old 90-day rule whereby you had to take the second exam 90 days after you have completed the first no longer applies.

Free A+ test to prepare you for your CompTIA A+ examArticle Image