What does the “&” symbol do?
select *
from emp
where ename like '&A%';
I infer you are using Oracle RDBMS since EMP.ENAME is from one of the example schemas from Oracle. In Oracle the ampersand "&" can be used as a substitution variable in SQL*Plus (client). See http://oracle-base.com/articles/misc/literals-substitution-variables-and-bind-variables.php#substitution_variables.
99% of the time, you are probably not doing substitution and want a literal ampersand. Such as INSERT INTO sometable VALUES ('Black & Decker'); So you would disable substitution first in SQL*Plus with SET DEFINE OFF.
It doesn't do or mean anything special in SQL string literal. It is just stands for itself; i.e. the ampersand character. So like '&A%' means a string that starts with '&A'.
Apparently (Joshua's answer), the ampersand can have special meaning in Oracle SQLPlus. But that isn't SQL. It is a different language that has SQL syntax embedded in it.
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 inserting text from a file into a table, few of the lines have words like "you'll" or "don't". When I insert these lines as varchar in my table, I get an error saying - near "ll": syntax error. How do I overcome this?
Your single quote is being considered as the end of your string. Escape the quote that exists within your string to avoid this problem.
You need to escape your SQL statement. If you are using SQL Server, then you can use QUOTENAME to resolve this.
Use two apostrophes within apostrophe-quoted strings to insert the apostrophe:
insert into footable (foo) values('you''ll')
Thank you all for responses, since I was using sqlite3, there are inbuilt string formating functions available with the library, so I was able to use sqlite3_mprintf with %q instead of %s and it took care of single quotes.
I'm trying to see if a particular column in a table in my Oracle database has any strings which contain a newline character, so a wildcard, a newline, and another wildcard.
I've tried the like command and a combination with CHR(10) and tried escaping the newline itself, but to no avail. What would be the proper way to detect a newline in somewhere within a string?
Thanks!
like '%'||chr(10)||'%' ought to work.
select * from yourTable where InStr(yourCol, Chr(10))>0 would work
I'm looking for the db2 equivalent of T-SQL's:
INSERT INTO People (Surname) VALUES ('O''Hara');
Use two apostrophes '' to get a single apostrophe on DB2 too, according to the DB2 Survival Guide. Isn't that working for you?
Brabster is correct. You are supposed to escape ' with ''
So to insert O'Hara , you will have to write O''Hara
Excerpt from:
http://www.michael-thomas.com/tech/db2/db2_survival_guide.htm
Escape character.
To insert a single quote, use 2 single
quotes ( '' ). To insert pet's use
the following pet''s.
Example: insert into MYTABLE (question,answer) values ('What is
your pet''s name?','blacky') `
just make it simple.
Keep your query in the single quotes ('). and where ever you are using qoutes, make it double.
for e.g. u want to insert ...... I'm fine. There's an answer.
in SQL we need to give ....... 'I''m fine. There''s an answer.'
I was trying to insert into DB2 a regex expression for an email address. I thought I had to escape all characters as outlined at the proceeding link, but escaping only the single quote contained within the regex seems to be all I needed to escape to get it properly inserted into the database:
https://www.ibm.com/support/knowledgecenter/en/SSEPGG_10.1.0/com.ibm.db2.luw.admin.ts.doc/doc/c0059609.html