I am working with a string column in redshift database where the instance of \" occurs multiple times in the same value.
I want to replace every occurrence of \" with "
For example, if a string = \"name\"
I want the output to be string = "name"
From what I have found, redshift does not allow the existence of a single backslash, and automatically converts it to a double backslash, but that is not happening in this case.
I have tried to use the REPLACE() with REPLACE( string, '\"', '"' ) but it did not have any effect. Can the string being a JSON string have any bearing on the function of REPLACE()?
I have been trying to use regexp_replace but maybe I am not using the right regular expression, hence I am not able to solve the problem.
REPLACE( string, '\\"', '"' ) seems works in this situation. I am guessing its because redshift doesn't allow a single backslash, but converts them to double backslash.
So, even though the string looked like \"name\" it was probably stored as \\"name\\" and hence putting a single backslash in the replace was not working.
EDIT: please read Bill's explanation in the comment below this reply
Related
I'm trying to delimit a string based off of a backslash, I tried using the token function but then realized that the '\' character is an escape character. Is there any way to delimit the string off of a backslash?
This is what my token function currently looks like.
Token(#[User::DynamicFilename],"\", 7)
FIrst of all use double backslash \\ instead of one \, and you should use TOKEN with TOKEN Count functions in order to retrieve the file name:
TOKEN(#[User::DynamicFilename],"\\", TOKENCOUNT(#[User::DynamicFilename],"\\"))
So if you are looking to extract a filename from a full file path tokencount will detect the latest occurence of backslash. Example:
Consider that #[User::DynamicFilename] value is:
C:\My Files\Folder\file.txt
Since the TOKENCOUNT() will return 3 then the expression be will be
TOKEN(#[User::DynamicFilename],"\\",3)
And it will returns
File.txt
You need to put double the number of your backslashes.
In your example, it should be
Token(#[User::DynamicFilename],"\\", 7)
If you don't know how deep to go with token, i suggest the following to get your result.
right(#[User::DynamicFilename],findstring(reverse(#[User::DynamicFilename]),"\\")-1)
I am trying to remove ";" semi-colon from a string.
What command in HIVE SQL should I use. I know regexp_replace may work..but what to put ?
It appears that ; - the special character does not work but other special characters like , or : works.
For example ,
Data looks like
;;;;;0123445
I want the data to look like this
0123445
Any help on this will be appreciated. I have been struggling with this.
REGEXP_REPLACE indeed looks like a good pick. For example, this removes all semicolons from the field :
REGEXP_REPLACE(my_column, ';', '')
From the documentation :
Returns the string resulting from replacing all substrings in INITIAL_STRING that match the java regular expression syntax defined in PATTERN with instances of REPLACEMENT.
Please note that the semicolon has no special meaning in the regexp language.
If you want to match on semicolons on the beginning of the string only (as shown in your question), use regexp special character ^, which indicates the beginning of the string
REGEXP_REPLACE(my_column, '^;', '')
To remove all semicolons, you can simply use replace():
replace(my_column, ';', '')
To remove leading semicolons, you can use:
replace(my_column, '^;+', '')
In Hive you need to escape the semi-colon.
regexp_replace(column_name,'\;','')
Im trying to use the TRIM command in SQL to Remove special characters from a string. thing is i cant seem to figure out how to remove the ' character like how when people use it in their surname.
e.g O'Reilly
in order to remove a character i have to quote it, but how can put in quotes or identify the character ' when it is used for quoting.
You want to use replace() and not trim(). Then, the escaping of single quotes requires doubling it, plus the outer single quotes. So:
replace(name, '''', '')
---------------^^ escaped single quote
--------------^--^ string delimiter for the single quote character
Use Replace function to replace that character (').
replace(name,"'","");
Link 1
Link 2
From within an Oracle 11g database, using SQL, I need to remove the following sequence of special characters from a string, i.e.
~!##$%^&*()_+=\{}[]:”;’<,>./?
If any of these characters exist within a string, except for these two characters, which I DO NOT want removed, i.e.: "|" and "-" then I would like them completely removed.
For example:
From: 'ABC(D E+FGH?/IJK LMN~OP' To: 'ABCD EFGHIJK LMNOP' after removal of special characters.
I have tried this small test which works for this sample, i.e:
select regexp_replace('abc+de)fg','\+|\)') from dual
but is there a better means of using my sequence of special characters above without doing this string pattern of '\+|\)' for every special character using Oracle SQL?
You can replace anything other than letters and space with empty string
[^a-zA-Z ]
here is online demo
As per below comments
I still need to keep the following two special characters within my string, i.e. "|" and "-".
Just exclude more
[^a-zA-Z|-]
Note: hyphen - should be in the starting or ending or escaped like \- because it has special meaning in the Character class to define a range.
For more info read about Character Classes or Character Sets
Consider using this regex replacement instead:
REGEXP_REPLACE('abc+de)fg', '[~!##$%^&*()_+=\\{}[\]:”;’<,>.\/?]', '')
The replacement will match any character from your list.
Here is a regex demo!
The regex to match your sequence of special characters is:
[]~!##$%^&*()_+=\{}[:”;’<,>./?]+
I feel you still missed to escape all regex-special characters.
To achieve that, go iteratively:
build a test-tring and start to build up your regex-string character by character to see if it removes what you expect to be removed.
If the latest character does not work you have to escape it.
That should do the trick.
SELECT TRANSLATE('~!##$%sdv^&*()_+=\dsv{}[]:”;’<,>dsvsdd./?', '~!##$%^&*()_+=\{}[]:”;’<,>./?',' ')
FROM dual;
result:
TRANSLATE
-------------
sdvdsvdsvsdd
SQL> select translate('abc+de#fg-hq!m', 'a+-#!', etc.) from dual;
TRANSLATE(
----------
abcdefghqm
I need a complete list of characters that should be escaped in sql string parameters to prevent exceptions. I assume that I need to replace all the offending characters with the escaped version before I pass it to my ObjectDataSource filter parameter.
No, the ObjectDataSource will handle all the escaping for you. Any parametrized query will also require no escaping.
As others have pointed out, in 99% of the cases where someone thinks they need to ask this question, they are doing it wrong. Parameterization is the way to go. If you really need to escape yourself, try to find out if your DB access library offers a function for this (for example, MySQL has mysql_real_escape_string).
SQL Books online:
Search for String Literals:
String Literals
A string literal consists of zero or more characters surrounded by quotation marks. If a string contains quotation marks, these must be escaped in order for the expression to parse. Any two-byte character except \x0000 is permitted in a string, because the \x0000 character is the null terminator of a string.
Strings can include other characters that require an escape sequence. The following table lists escape sequences for string literals.
\a
Alert
\b
Backspace
\f
Form feed
\n
New line
\r
Carriage return
\t
Horizontal tab
\v
Vertical tab
\"
Quotation mark
\
Backslash
\xhhhh
Unicode character in hexadecimal notation
Here's a way I used to get rid of apostrophes. You could do the same thing with other offending characters that you run into. (example in VB.Net)
Dim companyFilter = Trim(Me.ddCompany.SelectedValue)
If (Me.ddCompany.SelectedIndex > 0) Then
filterString += String.Format("LegalName like '{0}'", companyFilter.Replace("'", "''"))
End If
Me.objectDataSource.FilterExpression = filterString
Me.displayGrid.DataBind()