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');
I am fairly new to U-SQL and trying to run a U-SQL script in Azure Data Lake Analytics to process a parquet file using the Parquet extractor functionality. I am getting the below error and I don't find a way to get around it.
Error - Change the identifier to use at least one lower case letter. If that is not possible, then escape that identifier (for example: '[ACTIVITY]'), or embed it in a CSHARP() block (e.g CSHARP(ACTIVITY)).
Unfortunately all the different fields generated in the Parquet file are capitalized and I don't want to to escape these identifiers. I have tried if I could wrap the identifier with CSHARP block and it fails as well (E_CSC_USER_RESERVEDKEYWORDASIDENTIFIER: Reserved keyword CSHARP is used as an identifier.) Is there anyway I could extract the parquet file? Thanks for your help!
Code Snippet:
SET ##FeaturePreviews = "EnableParquetUdos:on";
#var1 =
EXTRACT ACTIVITY string,
AUTHOR_NAME string,
AFFLIATION string
FROM "adl://xxx.azuredatalakestore.net/Abstracts/FY2018_028"
USING Extractors.Parquet();
#var2 =
SELECT *
FROM #var1
ORDER BY ACTIVITY ASC
FETCH 5 ROWS;
OUTPUT #var2
TO "adl://xxx.azuredatalakestore.net/Results/AbstractsResults.csv"
USING Outputters.Csv();
Based on your description you try to say
EXTRACT ALLCAPSNAME int FROM "/data.parquet" USING Extractors.Parquet();
In U-SQL, we reserve all caps identifiers so we can add new keywords in the future without invalidating old scripts.
To work around, you just have to quote the name (escape it) like in any other SQL dialect:
EXTRACT [ALLCAPSNAME] int FROM "/data.parquet" USING Extractors.Parquet();
Note that this is not changing the name of the field. It is just the syntactic way to address the field.
Also note, that in most SQL communities, it is considered a best practice to always quote identifiers to avoid reserved keyword clashes.
If all fields in the Parquet file are all caps, you will have to quote them all... In a future update you will be able to say EXTRACT * FROM … for Parquet (and Orc) files, but you still will need to quote the columns when you refer to them explicitly.
Let's say I have this variable:
st='MI'
and I want to convert it to:
st=''' 'MI' '''
to use it in a SQL command.
What's the best way to accomplish this?
Thanks in advance!
Tripleor single quoting are just ways of typing strings into source code files.
Once your program is running, your string is already a string, and there is no need to make any cnversion to use it as a parameter to a SQL driver function call.
What you may want i to have a string with an SQL statement that itself contains various (single or double) quote characters. If that is typed in your Python source code file, you can type the triple-quote straight. If you are getting these SQL statements from elsewhere, they are already strings, as I said above.
Now, there are a few instances in which you have a string in a running Python program, or a Python interactive session, that you would like printed, so that you can paste it directly in source code. For these cases you can try the "unicode_escape" codec (and recode it to text so that it does not double your backslashes:
In [56]: print("\n".encode("unicode_escape").decode("utf-8"))
\n
I'm using the LibreOffice Basic language.
I'm wondering if there is any library anywhere I can use for splitting strings into arrays? For example, suppose I have the following string with items separated by an arbitrary number of spaces:
ABC DEF GHI
I'd like to split this string into an array called "item" with the following elements:
item(0) = "ABC"
item(1) = "DEF"
item(2) = "GHI"
I know how to produce these results in LibreOffice Basic using regular expressions or via iterating character-by-character through the original string, but I'm wondering if there are any existing functions or helper utilities I can use, so I don't have to "re-invent the wheel".
Internet searches have not yielded anything, but I could possibly have overlooked something.
Thank you in advance.
It looks like you will need to write your own function. There are several ideas at https://forum.openoffice.org/en/forum/viewtopic.php?f=9&t=33218.
If you will be doing a lot of string manipulation and the project is not too far along yet, then it might be worth considering another UNO-enabled language like Java or Python. In Python the code would be simply:
s = "ABC DEF GHI"
item = s.split()
In MATLAB, ... is used to continue a line to the next line. But if I want to continue a long string within quotation, what can I do? ... will be treated as a part of the string itself.
Using [] is not a perfect solution since in most cases I use sprintf/fprintf to parse a long string like sql query. Using [] would be cumbersome. thanks.
If you put the string in brackets, you can build it in several pieces:
s = ['abc' 'def' ...
'ghi'];
You can then split that statement into several lines between the strings.
answer=['You can divide strings '...
,'by adding a comma '...
,'(as you probably know one year later).'];
You can use strcat or horzcat, which gives you somewhat more options than [], including the ability to mix in variables along with the hardcoded values.