I'm trying to read data from ScyllaDB and want to remove \n and \r character from a column. The problem is that these characters are stored as string in the column of a table being read and I need to use REGEX_REPLACE as I'm using Spark SQL for this. The regex pattern don't seem to work which work in MySQL. The string becomes blank but doesn't remove the characters. Below is the snippet of the query being used in Spark SQL. Help appreciated.
The following string is present in the message column: 'hello\nworld\r'
The expected output is 'hello world'
df=spark.sql("select REGEXP_REPLACE(message,'\n|\r|\r\n',' ') as replaced_message from delivery_sms")
Thanks Andrew's for the answer.
The following worked for me:
df.withColumn("test",regexp_replace("_c0","\\\\n|\\\\r"," ")).show()
If anybody is looking for a modern solution to this problem:
df.select(
F.translate(F.col("test"), "\n\t", " " * len("\n\t")).alias("test")
)
I have a glue job, in which am reading table from SF using soql:
df = (
spark.read.format("com.springml.spark.salesforce")
.option("soql", sql)
.option("queryAll", "true")
.option("sfObject", sf_table)
.option("bulk", bulk)
.option("pkChunking", pkChunking)
.option("version", "51.0")
.option("timeout", "99999999")
.option("username", login)
.option("password", password)
.load()
)
and whenever there is a combination of double-quotes and commas in the string it messes up my table schema, like so:
in source:
Column A
Column B
Column C
000AB
"text with, comma"
123XX
read from SF in df :
Column A
Column B
Column C
000AB
"text with
comma"
Is there any option to avoid such cases when this comma is treated as a delimiter? I tried various options but nothing worked. And SOQL doesn't accept REPLACE or SUBSTRING functions, their text manipulation functions are, well, basically there aren't any.
All the information I'm giving need to be tested. I do not have the same env so it is difficult for me to try anything but here is what I foud.
When you check the official doc, you find that there is a field metadataConfig. The documentation of this field can be found here : https://resources.docs.salesforce.com/sfdc/pdf/bi_dev_guide_ext_data_format.pdf
On page 2, csv format, it says :
If a field value contains a control character or a new line the field value must be contained within double quotes (or your
fieldsEscapedBy value). The default control characters (fieldsDelimitedBy, fieldsEnclosedBy,
fieldsEscapedBy, or linesTerminatedBy) are comma and double quote. For example, "Director of
Operations, Western Region".
which kinda sounds like you current problem.
By default, the values are comma and double quotes, so, I do not understand why it is failing. But, apparently, in your output, it keeps the double quotes, so, maybe, it considers only simple quote.
You should try to enforce the format and add in you code :
.option("metadataConfig", '{"fieldsEnclosedBy": "\"", "fieldsDelimitedBy": ","}')
# Or something similar - i could'nt test, so you need to try by yourself
I have a table test(id,name).
I need to insert values like: user's log, 'my user', customer's.
insert into test values (1,'user's log');
insert into test values (2,''my users'');
insert into test values (3,'customer's');
I am getting an error if I run any of the above statements.
If there is any method to do this correctly please share. I don't want any prepared statements.
Is it possible using sql escaping mechanism?
String literals
Escaping single quotes ' by doubling them up → '' is the standard way and works of course:
'user's log' -- incorrect syntax (unbalanced quote)
'user''s log'
Plain single quotes (ASCII / UTF-8 code 39), mind you, not backticks `, which have no special purpose in Postgres (unlike certain other RDBMS) and not double-quotes ", used for identifiers.
In old versions or if you still run with standard_conforming_strings = off or, generally, if you prepend your string with E to declare Posix escape string syntax, you can also escape with the backslash \:
E'user\'s log'
Backslash itself is escaped with another backslash. But that's generally not preferable.
If you have to deal with many single quotes or multiple layers of escaping, you can avoid quoting hell in PostgreSQL with dollar-quoted strings:
'escape '' with '''''
$$escape ' with ''$$
To further avoid confusion among dollar-quotes, add a unique token to each pair:
$token$escape ' with ''$token$
Which can be nested any number of levels:
$token2$Inner string: $token1$escape ' with ''$token1$ is nested$token2$
Pay attention if the $ character should have special meaning in your client software. You may have to escape it in addition. This is not the case with standard PostgreSQL clients like psql or pgAdmin.
That is all very useful for writing PL/pgSQL functions or ad-hoc SQL commands. It cannot alleviate the need to use prepared statements or some other method to safeguard against SQL injection in your application when user input is possible, though. #Craig's answer has more on that. More details:
SQL injection in Postgres functions vs prepared queries
Values inside Postgres
When dealing with values inside the database, there are a couple of useful functions to quote strings properly:
quote_literal() or quote_nullable() - the latter outputs the unquoted string NULL for null input.
There is also quote_ident() to double-quote strings where needed to get valid SQL identifiers.
format() with the format specifier %L is equivalent to quote_nullable().
Like: format('%L', string_var)
concat() or concat_ws() are typically no good for this purpose as those do not escape nested single quotes and backslashes.
According to PostgreSQL documentation (4.1.2.1. String Constants):
To include a single-quote character within a string constant, write
two adjacent single quotes, e.g. 'Dianne''s horse'.
See also the standard_conforming_strings parameter, which controls whether escaping with backslashes works.
This is so many worlds of bad, because your question implies that you probably have gaping SQL injection holes in your application.
You should be using parameterized statements. For Java, use PreparedStatement with placeholders. You say you don't want to use parameterised statements, but you don't explain why, and frankly it has to be a very good reason not to use them because they're the simplest, safest way to fix the problem you are trying to solve.
See Preventing SQL Injection in Java. Don't be Bobby's next victim.
There is no public function in PgJDBC for string quoting and escaping. That's partly because it might make it seem like a good idea.
There are built-in quoting functions quote_literal and quote_ident in PostgreSQL, but they are for PL/PgSQL functions that use EXECUTE. These days quote_literal is mostly obsoleted by EXECUTE ... USING, which is the parameterised version, because it's safer and easier. You cannot use them for the purpose you explain here, because they're server-side functions.
Imagine what happens if you get the value ');DROP SCHEMA public;-- from a malicious user. You'd produce:
insert into test values (1,'');DROP SCHEMA public;--');
which breaks down to two statements and a comment that gets ignored:
insert into test values (1,'');
DROP SCHEMA public;
--');
Whoops, there goes your database.
In postgresql if you want to insert values with ' in it then for this you have to give extra '
insert into test values (1,'user''s log');
insert into test values (2,'''my users''');
insert into test values (3,'customer''s');
you can use the postrgesql chr(int) function:
insert into test values (2,'|| chr(39)||'my users'||chr(39)||');
When I used Python to insert values into PostgreSQL, I also met the question: column "xxx" does not exist.
The I find the reason in wiki.postgresql:
PostgreSQL uses only single quotes for this (i.e. WHERE name = 'John'). Double quotes are used to quote system identifiers; field names, table names, etc. (i.e. WHERE "last name" = 'Smith').
MySQL uses ` (accent mark or backtick) to quote system identifiers, which is decidedly non-standard.
It means PostgreSQL can use only single quote for field names, table names, etc. So you can not use single quote in value.
My situation is: I want to insert values "the difference of it’s adj for sb and it's adj of sb" into PostgreSQL.
How I figure out this problem:
I replace ' with ’, and I replace " with '. Because PostgreSQL value does not support double quote.
So I think you can use following codes to insert values:
insert into test values (1,'user’s log');
insert into test values (2,'my users');
insert into test values (3,'customer’s');
If you need to get the work done inside Pg:
to_json(value)
https://www.postgresql.org/docs/9.3/static/functions-json.html#FUNCTIONS-JSON-TABLE
You must have to add an extra single quotes -> ' and make doubling quote them up like below examples -> ' ' is the standard way and works of course:
Wrong way: 'user's log'
Right way: 'user''s log'
problem:
insert into test values (1,'user's log');
insert into test values (2,''my users'');
insert into test values (3,'customer's');
Solutions:
insert into test values (1,'user''s log');
insert into test values (2,'''my users''');
insert into test values (3,'customer''s');
Please help me in understanding what does the below code really mean?
CASE WHEN REPLACE(tablename.columnname,CHR(13),'') <> ''
THEN
REPLACE(tablename.columnname,CHR(13), '')
ELSE
REPLACE(tablename.columnname,CHR(13),'')
For your reference:
tablename.columname = mara.matnr
mara is a table and matnr is a field name in the table Mara.
CHR(13) is a carriage return, sometimes seen in text fields. I've worked on a number of solutions where I had to strip those out of strings so that when I displayed them on a reporting front-end (such as Excel), they didn't go to a new row. That is essentially what this code is doing - removing carriage returns by replacing them with a zero-length string.
The CASE expression you reference above is essentially useless, since it is using the same expression in both the THEN and ELSE. The entire script could be rewritten as:
REPLACE(tablename.columnname,CHR(13),'')
I need to update a record, which contains literal percent signs, using PostgreSQL in Railo. The query looks like
<cfquery>
update foo set bar = 'string with % in it %'
</cfQuery>
It throws error as ColdFusion normally interprets it as a wildcard character. I can escape it using the following query.
<cfquery>
update foo set bar = 'string with escaped \% in it \%'
</cfQuery>
However, the record now contains "\%" in the database and will be displayed on the page as "\%".
I found a documentation with an example of escaping percent sign in a SELECT. But it does not work for me: syntax error at or near "ESCAPE".
SELECT emp_discount
FROM Benefits
WHERE emp_discount LIKE '10\%'
ESCAPE '\';
Is there a better to achieve the same goal? The underlining database is PostgreSQL. Thanks!
Queryparameters escape special characters. Yet another reason to use them.