I have the following query:
CREATE TABLE FOR_DELETE([DATE] DATE )
but it seems that there is a difference in escaping special words as INT, DATE and so on and its not like in SQL... How to escape special word?
Standard SQL would use double-quotes ("), and some implementations may use backticks (`). Out of the top of my head, Oracle will take the double-quotes.
Related
I am working with a malformed database which seems to have double quotes as part of the column names.
Example:
|"Market" |
|---------|
|Japan |
|UK |
|USA |
And I want to select like below
SELECT "\"Market\"" FROM mytable; /* Does not work */
How does one select such a thing?
The documentation says
[A] delimited identifier or quoted identifier […] is formed by enclosing an arbitrary sequence of characters in double-quotes ("). […]
Quoted identifiers can contain any character, except the character with code zero. (To include a double quote, write two double quotes.)
So you'll want to use
SELECT """Market""" AS "Market" FROM mytable;
An alternative would be
A variant of quoted identifiers allows including escaped Unicode characters identified by their code points. This variant starts with U& (upper or lower case U followed by ampersand) immediately before the opening double quote, without any spaces in between, for example U&"foo". […] Inside the quotes, Unicode characters can be specified in escaped form by writing a backslash followed by the four-digit hexadecimal code point number or alternatively a backslash followed by a plus sign followed by a six-digit hexadecimal code point number.
which in your case would mean
SELECT U&"\0022Market\0022" AS "Market" FROM mytable;
SELECT U&"\+000022Market\+000022" AS "Market" FROM mytable;
Disclaimer: your database may not actually have double quotes as part of the name itself. As mentioned in the comments, this might just be the way in which the tool you are using does display a column named Market (not market) since
Quoting an identifier also makes it case-sensitive
So all you might need could be
SELECT "Market" FROM mytable;
I'm trying to match a certain text that includes a single quote (i.e. 'company's report...')
normally I would have used the E' literal + ' or double single quotes.
but when it gets to using the LIKE '%' operator, things got complicated.
what is the best approach to match a text with a single quote?
You can escape single quote with another single quote. Example:
WHERE column LIKE 'RSNboim''s'
From https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS
To include a single-quote character within a string constant, write two adjacent single quotes, e.g., 'Dianne''s horse'. Note that this is not the same as a double-quote character (").
You can use Dollar-quoted String Constants at Lexical Structure
Your condition should be something like below;
select * from atable
where afield like $$Dianne's %$$
Question (because I can't work it out), should ""hello world"" be a valid field value in a CSV file according to the specification?
i.e should:
1,""hello world"",9.5
be a valid CSV record?
(If so, then the Perl CSV-XS parser I'm using is mildly broken, but if not, then $line =~ s/\342\200\234/""/g; is a really bad idea ;) )
The weird thing is is that this code has been running without issue for years, but we've only just hit a record that started with both a left double quote and contained no comma (the above is from a CSV pre-parser).
The canonical format definition of CSV is https://www.rfc-editor.org/rfc/rfc4180.txt. It says:
Each field may or may not be enclosed in double quotes (however
some programs, such as Microsoft Excel, do not use double quotes
at all). If fields are not enclosed with double quotes, then
double quotes may not appear inside the fields. For example:
"aaa","bbb","ccc" CRLF
zzz,yyy,xxx
Fields containing line breaks (CRLF), double quotes, and commas
should be enclosed in double-quotes. For example:
"aaa","b CRLF
bb","ccc" CRLF
zzz,yyy,xxx
If double-quotes are used to enclose fields, then a double-quote
appearing inside a field must be escaped by preceding it with
another double quote. For example:
"aaa","b""bb","ccc"
Last rule means your line should have been:
1,"""hello world""",9.5
But not all parsers/generators follow this standard perfectly, so you might need for interoperability reasons to relax some rules. It all depends on how much you control the CSV format writing and CSV format parsing parts.
That depends on the escape character you use. If your escape character is '"' (double quote) then your line should look like
1,"""hello world""",9.5
If your escape character is '\' (backslash) then your line should look like
1,"\"hello world\"",9.5
Check your parser/environment defaults or explicitly configure your parser with the escape character you need e.g. to use backslash do:
my $csv = Text::CSV_XS->new ({ quote_char => '"', escape_char => "\\" });
I have a database entry that has entries that look like this:
id | name | code_set_id
I have this particular entry that I need to find:
674272310 | raphodo/qrc_resources.py | 782732
In my rails app (2.3.8), I have a statement that evaluates to this:
SELECT * from fyles WHERE code_set_id = 782732 AND name LIKE 'raphodo/qrc\\_resources.py%';
From reading up on escaping, the above query is correct. This is supposed to correctly double escape the underscore. However this query does not find the record in the database. These queries will:
SELECT * from fyles WHERE code_set_id = 782732 AND name LIKE 'raphodo/qrc\_resources.py%';
SELECT * from fyles WHERE code_set_id = 782732 AND name LIKE 'raphodo/qrc_resources.py%';
Am I missing something here? Why is the first SQL statement not finding the correct entry?
A single backslash in the RHS of a LIKE escapes the following character:
9.7.1. LIKE
[...]
To match a literal underscore or percent sign without matching other characters, the respective character in pattern must be preceded by the escape character. The default escape character is the backslash but a different one can be selected by using the ESCAPE clause. To match the escape character itself, write two escape characters.
So this is a literal underscore in a LIKE pattern:
\_
and this is a single backslash followed by an "any character" pattern:
\\_
You want LIKE to see this:
raphodo/qrc\_resources.py%
PostgreSQL used to interpret C-stye backslash escapes in strings by default but no longer, now you have to use E'...' to use backslash escapes in string literals (unless you've changed the configuration options). The String Constants with C-style Escapes section of the manual covers this but the simple version is that these two:
name LIKE E'raphodo/qrc\\_resources.py%'
name LIKE 'raphodo/qrc\_resources.py%'
do the same thing as of PostgreSQL 9.1.
Presumably your Rails 2.3.8 app (or whatever is preparing your LIKE patterns) is assuming an older version of PostgreSQL than the one you're actually using. You'll need to adjust things to not double your backslashes (or prefix the pattern string literals with Es).
All,
I am trying to clean up data in a SQLite database, that contains tons of escaped single and double quotes.
Example: \"Text\" has \'junk\' like this all over the place.
When I do a SELECT to see if the REPLACE function has the correct pattern, the REPLACE is not working:
-- replace escaped single quotes
SELECT id,subject,body,replace(body,"\\'","'") as `clean-body`
FROM article
WHERE id=1118
Thanks for looking
There is no need to escape the backslash. Try this in place of your original call to replace:
replace(body,"\'","'")