I have an SQL column where the entries are strings. I need to display those entries after trimming the last two characters, e.g. if the entry is 199902345 it should output 1999023.
I tried looking into TRIM but looks like it offers to trim only if we know what are the last two characters. But in my case, I don't know what those last two numbers are and they just need to be discarded.
So, in short, what MySQL string operation enables to trim the last two characters of a string?
I must add that the length of the string is not fixed. It could be 9 characters, 11 characters or whatsoever.
To select all characters except the last n from a string (or put another way, remove last n characters from a string); use the SUBSTRING and CHAR_LENGTH functions together:
SELECT col
, /* ANSI Syntax */ SUBSTRING(col FROM 1 FOR CHAR_LENGTH(col) - 2) AS col_trimmed
, /* MySQL Syntax */ SUBSTRING(col, 1, CHAR_LENGTH(col) - 2) AS col_trimmed
FROM tbl
To remove a specific substring from the end of string, use the TRIM function:
SELECT col
, TRIM(TRAILING '.php' FROM col)
-- index.php becomes index
-- index.php.php becomes index (!)
-- index.txt remains index.txt
Why not using LEFT(string, length) function instead of substring.
LEFT(col,char_length(col)-2)
you can visit here https://dev.mysql.com/doc/refman/5.7/en/string-functions.html#function_left to know more about Mysql String Functions.
substring().
http://dev.mysql.com/doc/refman/5.0/en/string-functions.html
You can use a LENGTH(that_string) minus the number of characters you want to remove in the SUBSTRING() select perhaps or use the TRIM() function.
Related
I have a dataset where the values are different, and I want to bring them into a single format.The values are stored as varchar
For ex.
1st Case: 1.23.45 should be 123.45
2nd Case: 125.45 should be 125.45
The first one, has two decimals. I want to remove the first decimal only(if there are 2) else let the value be as it is.
How do I do this?
I tried using replace(Qty,'.',''). But this is removing of them.
I think this can do (although I am not 100% sure about corner cases)
SET Qty = SUBSTRING(Qty, 1, LOCATE(Qty, '.') - 1) + SUBSTRING(Qty, LOCATE(Qty, '.') + 1, LENGTH(Qty) - LOCATE(Qty, '.') - 1)
WHERE LENGTH(Qty) - LENGTH(REPLACE(Qty, '.', '')
You can use a regular expression to handle this case.
Assuming there are only two decimals in your string the below query should be able to handle the case.
select (value,'^(\d+)(\.)?(\d+\.\d+)$',concat('$1','$2')) as a
Here we are matching a regular expression pattern and capturing the following
digits before first decimal occurrence in group one
digits before and after last decimal occurrence including the last decimal in group two.
Following that we are concatenating the two captured groups.
Note that the first decimal has been made optional using ? character and hence we are able to handle both type of cases.
Even if there are more than two decimal cases, I believe a properly constructed regular expression should be able to handle it.
I have a list of numbers in some fields in a table, for example something like this:
2033,1869,1914,1913,19120,1911,1910,1909,1908,1907,1866,1921,1922,1923
Now, I'm trying to do a query to check if a number is found in the row, however, I can't use LIKE as then it may return false positives as if I did a search for 1912 in the above field I would get a result returned because of the number 19120, obviously we don't want that - we can't append or prepend a comma as the start/end numbers don't have them.
So, onto using REGEXP I go... I tried this, but it doesn't work (it returns a result):
SELECT * FROM cat_listing WHERE cats REGEXP '[^0-9]*1912[^0-9]*';
I imagine why it still finds something is because of the * quantifier; it found [^0-9] 0 times AFTER 1912 so it considers it a match.
I'm not sure how to modify it to do what I want.
In your case, it seems word boundaries are necessary:
SELECT * FROM cat_listing WHERE cats REGEXP '[[:<:]]1912[[:>:]]';
[[:<:]] is the beginning of a word and [[:>:]] is the end. See reference:
[[:<:]], [[:>:]]
These markers stand for word boundaries. They match the beginning and end of >words, respectively. A word is a sequence of word characters that is not >preceded by or followed by word characters. A word character is an alphanumeric >character in the alnum class or an underscore (_).
You have another option called find_in_set()
SELECT * FROM cat_listing WHERE find_in_set('1912', cats) <> 0;
Returns 0 if str is not in strlist or if strlist is the empty string. Returns NULL if either argument is NULL. This function does not work properly if the first argument contains a comma (“,”) character.
No need to use a regex just because the column value has no comma at either end:
SELECT
cats
FROM cat_listing
WHERE INSTR(CONCAT(',', cats, ','), ',1912,')
;
See it in action: SQL Fiddle.
Please comment if adjustment / further detail is required.
I have a chemistry database (very small, about 60kb or so) in a mysql database. My
select * from firstdatabase;
works fine with any column but symbol. When I do
select * from firstdatabase where symbol = "Y";
for example, I get an empty set. However, when I do
select symbol from firstdatabase;
I get every symbol in the database including "Y". This problem doesn't occur with any other field except symbol. I have also tried it with double lettered and triple lettered elements to no avail. Please help?
My first guess is your symbol column contains whitespace characters. So you should try TRIM function.
select * from firstdatabase where TRIM(symbol) = "Y"
Use LTRIM and RTRIM if there whitespace characters in your symbol column.You should try LTRIM and RTRIM function.
select * from firstdatabase where LTRIM(RTRIM(symbol))= 'Y'
I have two databases, both containing phone numbers. I need to find all instances of duplicate phone numbers, but the formats of database 1 vary wildly from the format of database 2.
I'd like to strip out all non-digit characters and just compare the two 10-digit strings to determine if it's a duplicate, something like:
SELECT b.phone as barPhone, sp.phone as SPPhone FROM bars b JOIN single_platform_bars sp ON sp.phone.REGEX = b.phone.REGEX
Is such a thing even possible in a mysql query? If so, how do I go about accomplishing this?
EDIT: Looks like it is, in fact, a thing you can do! Hooray! The following query returned exactly what I needed:
SELECT b.phone, b.id, sp.phone, sp.id
FROM bars b JOIN single_platform_bars sp ON REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(b.phone,' ',''),'-',''),'(',''),')',''),'.','') = REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(sp.phone,' ',''),'-',''),'(',''),')',''),'.','')
MySQL doesn't support returning the "match" of a regular expression. The MySQL REGEXP function returns a 1 or 0, depending on whether an expression matched a regular expression test or not.
You can use the REPLACE function to replace a specific character, and you can nest those. But it would be unwieldy for all "non-digit" characters. If you want to remove spaces, dashes, open and close parens e.g.
REPLACE(REPLACE(REPLACE(REPLACE(sp.phone,' ',''),'-',''),'(',''),')','')
One approach is to create user defined function to return just the digits from a string. But if you don't want to create a user defined function...
This can be done in native MySQL. This approach is a bit unwieldy, but it is workable for strings of "reasonable" length.
SELECT CONCAT(IF(SUBSTR(sp.phone,1,1) REGEXP '^[0-9]$',SUBSTR(sp.phone,1,1),'')
,IF(SUBSTR(sp.phone,2,1) REGEXP '^[0-9]$',SUBSTR(sp.phone,2,1),'')
,IF(SUBSTR(sp.phone,3,1) REGEXP '^[0-9]$',SUBSTR(sp.phone,3,1),'')
,IF(SUBSTR(sp.phone,4,1) REGEXP '^[0-9]$',SUBSTR(sp.phone,4,1),'')
,IF(SUBSTR(sp.phone,5,1) REGEXP '^[0-9]$',SUBSTR(sp.phone,5,1),'')
) AS phone_digits
FROM sp
To unpack that a bit... we extract a single character from the first position in the string, check if it's a digit, if it is a digit, we return the character, otherwise we return an empty string. We repeat this for the second, third, etc. characters in the string. We concatenate all of the returned characters and empty strings back into a single string.
Obviously, the expression above is checking only the first five characters of the string, you would need to extend this, basically adding a line for each position you want to check...
And unwieldy expressions like this can be included in a predicate (in a WHERE clause). (I've just shown it in the SELECT list for convenience.)
MySQL doesn't support such string operations natively. You will either need to use a UDF like this, or else create a stored function that iterates over a string parameter concatenating to its return value every digit that it encounters.
Consider the string "55,33,255,66,55"
I am finding ways to count number of occurence of a specific characters ("55" in this case) in this string using mysql select query.
Currently i am using the below logic to count
select CAST((LENGTH("55,33,255,66,55") - LENGTH(REPLACE("55,33,255,66,55", "55", ""))) / LENGTH("55") AS UNSIGNED)
But the issue with this one is, it counts all occurence of 55 and the result is = 3,
but the desired output is = 2.
Is there any way i can make this work correct? please suggest.
NOTE : "55" is the input we are giving and consider the value "55,33,255,66,55" is from a database field.
Regards,
Balan
You want to match on ',55,', but there's the first and last position to worry about. You can use the trick of adding commas to the frot and back of the input to get around that:
select LENGTH('55,33,255,66,55') + 2 -
LENGTH(REPLACE(CONCAT(',', '55,33,255,66,55', ','), ',55,', 'xxx'))
Returns 2
I've used CONCAT to pre- and post-pend the commas (rather than adding a literal into the text) because I assume you'll be using this on a column not a literal.
Note also these improvements:
Removal of the cast - it is already numeric
By replacing with a string one less in length (ie ',55,' length 4 to 'xxx' length 3), the result doesn't need to be divided - it's already the correct result
2 is added to the length because of the two commas added front and back (no need to use CONCAT to calculate the pre-replace length)
Try this:
select CAST((LENGTH("55,33,255,66,55") + 2 - LENGTH(REPLACE(concat(",","55,33,255,66,55",","), ",55,", ",,"))) / LENGTH("55") AS UNSIGNED)
I would do an sub select in this sub select I would replace every 255 with some other unique signs and them count the new signs and the standing 55's.
If(row = '255') then '1337'
for example.