There is table column containing file names: image1.jpg, image12.png, script.php, .htaccess,...
I need to select the file extentions only. I would prefer to do that way:
SELECT DISTINCT SUBSTR(column,INSTR('.',column)+1) FROM table
but INSTR isn't supported in my version of SQLite.
Is there way to realize it without using INSTR function?
below is the query (Tested and verified)
for selecting the file extentions only. Your filename can contain any number of . charenters - still it will work
select distinct replace(column_name, rtrim(column_name,
replace(column_name, '.', '' ) ), '') from table_name;
column_name is the name of column where you have the file names(filenames can have multiple .'s
table_name is the name of your table
Try the ltrim(X, Y) function, thats what the doc says:
The ltrim(X,Y) function returns a string formed by removing any and all characters that appear in Y from the left side of X.
List all the alphabet as the second argument, something like
SELECT ltrim(column, "abcd...xyz1234567890") From T
that should remove all the characters from left up until .. If you need the extension without the dot then use SUBSTR on it. Of course this means that filenames may not contain more that one dot.
But I think it is way easier and safer to extract the extension in the code which executes the query.
Related
My data is string like:
'湯姆 is a boy.'
or '梅isagirl.'
or '約翰,is,a,boy.'.
And I want to split the string and only choose the Chinese name.
In R, I can use the command
tmp=strsplit(string,[A-z% ])
unlist(lapply(tmp,function(x)x[1]))
And then getting the Chinese name I want.
But in PostgreSQL
select regexp_split_to_array(string,'[A-z% ]') from db.table
I get a array like {'湯姆','','',''},{'梅','','',''},...
And I don't know how to choose the item in the array.
I try to use the command
select regexp_split_to_array(string,'[A-z% ]')[1] from db.table
and I get an error.
I don't think that regexp_split_to_array is the appropriate function for what you are trying to do here. Instead, use regexp_replace to selectively remove all ASCII characters:
SELECT string, regexp_replace(string, '[[:ascii:]~:;,"]+', '', 'g') AS name
FROM yourTable;
Demo
Note that you might have to adjust the set of characters to be removed, depending on what other non Chinese characters you expect to have in the string column. This answer gives you a general suggestion for how you might proceed here.
In my database, a table contains two columns each containing an 8 digit ASCII code, usually it's just alphanumeric. For example, a row might contain A123B45C in col1 and PQ2R4680 in col2.
I need to have a query/view that outputs a 4 character string calculated as the 2nd+3rd chars of these, concatenated. So in this example the extra column value would be 12Q2.
This is a cut-down version of the SQL I'd like to use, although it won't work as written because of zero stripping / conversion:
select
*,
(substr(col1, 2, 2) || substr(col2, 2, 2)) AS mode
from (nested SQL source query)
where (conditions)
This fails because if a row contains A00B23B4 in col1 and P32R4680 in col2, it will evaluate as 0032 and the query output will contain numeric 32 not 0032. (It's worse if col1 contains P1-2345 or "1.23456" or something like that)
Other questions on preventing zero stripping and string to integer conversion in Sqlite, all relate to data in tables where you can define a column text affinity, or static (quotable) data. In this case I can't do these things. I also can only create queries, not tables, so I can't write to a temp table.
What is the best way to ensure I get a 4 character output in all cases?
I believe you issue is not with substr stripping characters as this works as expected e.g. :-
Then running query SELECT substr(col1,2,2) || substr(col2,2,2) as mode FROM stripping
results in (as expected):-
Rather, your issue is likely how you subsequently utilise mode in which case you may need to use a CAST expression CAST expressions
For example the following does what is possibly happening :-
`SELECT substr(col1,2,2) || substr(col2,2,2) as mode, CAST(substr(col1,2,2) || substr(col2,2,2) AS INTEGER) AS oops FROM stripping`
resulting in :-
With NVARCHAR data type, I store my local language text in a column. I face a problem how to query that value from the database.
ዜናገብርኤልስ is stored value.
I wrote SQL like this
select DivisionName
from t_Et_Divisions
where DivisionName = 'ዜናገብርኤልስ'
select unicode (DivisionName)
from t_Et_Divisions
where DivisionName = 'ዜናገብርኤልስ'
The above didn't work. Does anyone have any ideas how to fix it?
Thanks!
You need to prefix your Unicode string literals with a N:
select DivisionName
from t_Et_Divisions
where DivisionName = N'ዜናገብርኤልስ'
This N prefix tells SQL Server to treat this string literal as a Unicode string and not convert it to a non-Unicode string (as it will if you omit the N prefix).
Update:
I still fail to understand what is not working according to you....
I tried setting up a table with an NVARCHAR column, and if I select, I get back that one, exact row match - as expected:
DECLARE #test TABLE (DivisionName NVARCHAR(100))
INSERT INTO #test (DivisionName)
VALUES (N'ዜናገብርኤልስ'), (N'ዜናገብርኤልስ,ኔትዎርክ,ከስተመር ስርቪስ'), (N'ኔትዎርክ,ከስተመር ስርቪስ')
SELECT *
FROM #test
WHERE DivisionName = N'ዜናገብርኤልስ'
This returns exactly one row - what else are you seeing, or what else are you expecting??
Update #2:
Ah - I see - the columns contains multiple, comma-separated values - which is a horrible design mistake to begin with..... (violates first normal form of database design - don't do it!!)
And then you want to select all rows that contain that search term - but only display the search term itself, not the whole DivisionName column? Seems rather pointless..... try this:
select N'ዜናገብርኤልስ'
from t_Et_Divisions
where DivisionName LIKE N'%ዜናገብርኤልስ%'
The LIKE searches for rows that contain that value, and since you already know what you want to display, just put that value into the SELECT list ....
I have a table which has a column named "directory" which contains strings like:
c:\mydir1\mysubdir1\
c:\mydir2
j:\myotherdir
...
I would like to do something like
SELECT FROM mytable WHERE directory is contained within 'c:\mydir2\something\'
This query should give me as a result:
c:\mydir2
Ok, I've just found that sqlite has a function instr that seems to work for my purpose.
Not sure about the performance, though.
I need to extract the filename without the extension from one of tables I have.
Currently I have used
SELECT filename FROM files
is used which returns the entire filename (Jessica.Timber.mp3). So is it possible to get only the filename using sqlite(eg: Jessica.Timber )? The files may contain multiple "." but only the last dot followed by the the ext should be removed.
I tried the following query, which provides the result if the extension is only 3 letter long (eg: *.mp3) but fails if its more than that (eg: *.flac)
SELECT substr(filename, -4, -100) from files;
Below is the query - will get you the file name without extension irrespective of extension length. File name can contain any number of . character (Tested and verified)
select replace(filename
, '.' || replace(filename
, rtrim(filename, replace(filename, '.', '') )
, '')
, '')
from files;
Test:
create table files (filename);
insert into files values ("ph.otoJpg.jpg"), ("ph.otoJpeg.jpeg");
Then the above code yields:
ph.otoJpg.
ph.otoJpeg.
SQLite has no built-in string functions that would help with this.
It would be possible to create a recursive CTE, but the easiest way is to retrieve the entire file name and to remove the extension in your code.