Your AskTOM Top 10 for 2018

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Here we go folks…here are the top 10 most viewed questions in AskTOM this year!

We’ll count them down from 10 to 1

10) Inserting values into a table with ‘&’

Viewed 80,000 times.

First asked in 2012, this actually is not a database issue but a client issue. Many client tools view ampersand as a substitution variable, and this they intercept the execution before the command is sent to the database. Full details here

9) What is a SID, how to change it, how to find out what it is

Viewed 95,000 times.

A timeless classic. This question was asked in June 2000 – only 1 month after AskTOM went live. Given that most of our documentation contains, and most people are aware of the terms “instance” and “database”, I’ll never really understand why we didn’t go with ORACLE_INSTANCE instead of ORACLE_SID. Full details here.

8) How to Update millions or records in a table

Viewed 100,000 times.

Asked back in 2002, I can understand the popularity of this one. Perhaps the most common performance tuning issue is data conversion or data loading. Sometimes you just need to forget the word UPDATE and re-load the data – it can be much faster. Full details here.

7) How to connect SQLPlus without tnsnames.ora

Viewed 110,000 times.

Is it that much of a big deal to have a tnsnames.ora file? I guess so. Nowadays the EZ connect syntax makes connecting to any database trivial. Full details here.


Viewed 130,000 times.

Another understandable one for the top 10 because of the transition from old style export/import to data pump around the timeframe that this question was first asked. There is also the classic chicken-and-egg issue to deal with, namely, that you need a database in order to import, but won’t a full import than clash with all the existing objects? Full details here.

5) Converting CLOBS TO VARCHAR

Viewed 132,000 times.

Once a golden oldie from 2001! It seems an odd proposition – if you have a CLOB, there’s a good chance you have it because it exceeds the allowable size for VARCHAR2. So converting back down seems a risky exercise. Full details here.

4) ORA-12560: TNS:protocol adapter error

Viewed 135,000 times.

Ah yes, not our finest hour this one. Try to use a database on Windows that has not been started, and do you get an error saying “Database not started”? No. You get a crytpic TNS error. Full details here.

3) Format the Number for display

Viewed 143,000 times.

There is such a thing as “too much of a good thing”. And perhaps our incredible flexibility when it comes to formatting data, and the range of format masks is tough for people to swallow. Full details here.

2) IN (vs) EXISTS and NOT IN (vs) NOT EXISTS

Viewed 144,000 times.

Well, there’s a simple reason this gem keeps on coming back year after year after year. For years, books on performance tuning and blogs on performance tuning would claim that EXISTS was better than IN, or vice versa. Amazingly it has never been the case that one was guaranteed to be better than the other, and more alarmingly a straight swap from one to the other can even impact the results you get back. I think we’ll see this guy in the list every year…..forever. Full details here.

And finally we have arrived at the number 1 most viewed question this year. Which begs me to ask the question:

Why do so many of you need to know how many are in each table? Smile

1) Finding the number of rows in each table by a single sql

Viewed 510,000 times.

Wow. Half a million people need to know how many rows are in their database tables. I’ve no idea why, because the moment you count them, you’re already out of date. Full details here.

And there you … our top 10 for 2018.

Have a great festive season!


  1. Even after 2+ years retired from Oracle and DBA work…. all this brings back old memories…. ha, good to see your light-hearted sense of humor here….. and thanks for all your help in the past!
    Merry Christmas! best wishes.

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