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up vote -1 down vote favorite

I am doing some string replace in SQL on the fly.

MySQLString = " a.account=b.account ";
MySQLString = " a.accountnum=b.accountnum ";

Now if I do this

MySQLString.replaceAll("account", "account_enc");

the result will be

a.account_enc=b.account_enc

(This is good)

But look at 2nd result

a.account_enc_num=a.account_enc_num

(This is not good it should be a.accountnum_enc=b.accountnum_enc)

Please advise how can I achieve what I want with Java String Replace.

Many Thanks.

share|improve this question
    
You should look at using a capturing group in your regex. –  Code-Apprentice Feb 23 '13 at 1:42
1  
Next time, try to explain exactly what you need better, perhaps saying: I want this, this and this to be replaced, but not this, this and this. –  Oscar Mederos Feb 23 '13 at 2:41
    
@OscarMederos apologies, will do. –  user2101374 Feb 23 '13 at 2:55

3 Answers 3

up vote 1 down vote accepted

From your comment:

Is there anyway to tell in Regex only replace a.account=b.account or a.accountnum=b.accountnum. I do not want accountname to be replace with _enc

If I understand correctly you want to add _enc part only to account or accountnum. To do this you can use 

MySQLString = MySQLString.replaceAll("\\baccount(num)?\\b", "$0_enc");

(num)? mean that num is optional so regex will accept account or accountnum

\\b at start mean that there can be no letters, numbers or "_" before account so it wont accept (affect) something like myaccount, or my_account.

\\b at the end will prevent other letters, numbers or "_" after account or accountnum.

share|improve this answer
    
beat me to it ;) –  Oscar Mederos Feb 23 '13 at 2:40
    
@OscarMederos hope OP wont say now something like "but I want it to update only if two words that I am changing are identical" so no change in a.account=b.accountnum :) (I've seen that before :D) –  Pshemo Feb 23 '13 at 2:46
    
I don't think so :) –  Oscar Mederos Feb 23 '13 at 2:47
    
@Pshemo I need to try it out in Java to be sure but if \\b prevents letters or numbers or underscore before account will it catch a.account i.e. a. before account? –  user2101374 Feb 23 '13 at 2:50
1  
@user2101374 if this answer solves your problem you can [accept] it as solution to mark your problem as solved so other users wont waste their time trying to create other answers :) –  Pshemo Feb 23 '13 at 2:59
up vote 0 down vote

It's hard to extrapolate from so few examples, but maybe what you want is:

MySQLString = MySQLString.replaceAll("account\\w*", "$0_enc");

which will append _enc to any sequence of letters, digits, and underscores that starts with account.

share|improve this answer
    
Thank you very much Ruakh, I will give it a try, many thanks, you guys are amazing. –  user2101374 Feb 23 '13 at 1:31
    
Hi Ruakh, this will even cause accountname to be changed to accountname_enc which I do not want, any other suggestion? –  user2101374 Feb 23 '13 at 1:35
    
@user2101374: How can you tell that you want accountnum_enc but not accountname_enc? –  ruakh Feb 23 '13 at 1:40
    
Hi Ruakh, I have a list of columns in a file which I know I need to add enc. Actually enc stands for encrypted so only account number need to be changed to _enc. The column name containing account can either be called account or accountnum. –  user2101374 Feb 23 '13 at 1:46
up vote 0 down vote

try

    String s = " a.accountnum=b.accountnum ".replaceAll("(account[^ =]*)", "$1_enc");

it means replace any sequence characters which are not ' ' or '=' which starts the word "account" with the sequence found + "_enc".

$1 is a reference to group 1 in regex; group 1 is the expression in parenthesis (account[^ =]+), i.e. our sequence

See http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html for details

share|improve this answer
    
Thanks Evgeniy, could you please explain the regex you have used? Apologies I am not very good at Regex want to understand does the regex you have used means –  user2101374 Feb 23 '13 at 1:44
    
OK, see my update –  Evgeniy Dorofeev Feb 23 '13 at 1:55
    
Evgeniy, wouldnt this even replace a.name=b.name with a.name_enc=b.name_enc? I only like to replace a.account=b.account to be a.account_enc=b.account_enc OR a.accountnum=b.accountnum to be a.accountnum_enc=b.accountnum_enc –  user2101374 Feb 23 '13 at 1:58
    
It wont after I've fixed it :), now I think you have enough examples to make corrections to the regex. –  Evgeniy Dorofeev Feb 23 '13 at 2:01
    
It seems there is just one issue with this Regex, it will even convert a.accountname=b.accountname to a.accountname_enc=b.accountname_enc, correct? Is there anyway to tell in Regex only replace a.account=b.account or a.accountnum=b.accountnum, I do not want accountname to be replace with _enc. Thank you very much. Very much appreciated :) –  user2101374 Feb 23 '13 at 2:04

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