First let me apologize I have not been successful in finding anything online with this specific scenario.
I have been using MySQL for quite some time, but I am hoping to get some clarification on a certain situation I have come across, which honestly bothers me quite a bit.
I'm trying to match a string in a MySQL column that contains both \ and % literal characters using the LIKE operator.
Inside the table I have two records:
id value
-----------------------
1 100\\%A
2 100\%A
They both contain literal special characters.
If I do a SELECT, in an attempt to only match the first record (id=1), I would expect to write the query as such:
SELECT * FROM table_name WHERE value LIKE '%0\\\\\%A'
(\\\\ to match two literal backslashes, plus a backslash before % to match a literal %)
However, It only matches the row (id=2), which makes no sense to me.
If I change the query a little to be:
SELECT * FROM table_name WHERE value LIKE '%0\\\\%A'
I would expect to match the id=1 row only, (\\\\ to match 2 literal backslashes, and the % is not literal and should represent a wildcard). But instead, it matches both rows?
row (id=2) only has a single backslash but still matches.
Is row id=2 matching because the first 2 backslashes are matching the \, the 3rd backslash is ignored for some reason, and the 4th backslash is allowing a literal match on the %?
If I do a:
SELECT * FROM table_name WHERE value LIKE '%0\\\\\\\%A'
I for some reason get row (id=1), when I would expect to get no matches whatsoever.
I'm trying to find a solution in which I can do partial matches on any series of characters accurately, including those with consecutive special characters such as the scenario above. However, I'm having an impossible time trying to plan for situations such as these.
Any input would be greatly appreciated.
Maybe this help you understand the usage of escape chars in mySQL
https://stackoverflow.com/a/27061961/634698
I want to match the string having escape characters with particular column in a table.
SELECT * FROM table WHERE col LIKE 'MESSRESTAURANGER AB\\MESSVEGEN 1\\STOCKH';
Though there is matching data in table, query result is empty set. But the same query works fine in oracle. What is the issue with mysql?
You miss %:
SELECT * FROM table WHERE col LIKE '%MESSRESTAURANGER AB\\MESSVEGEN 1\\STOCKH%';
But it should work without escaping:
SELECT * FROM table WHERE col LIKE '%MESSRESTAURANGER AB\MESSVEGEN 1\STOCKH%';
Fiddle http://sqlfiddle.com/#!9/a7ba59/2
EDIT:
SELECT * FROM t WHERE n LIKE '%MESSRESTAURANGER AB\\\\\\\\MESSVEGEN 1\\\\\\\\STOCKH%'
Because MySQL uses C escape syntax in strings (for example, “\n” to
represent a newline character), you must double any “\” that you use
in LIKE strings. For example, to search for “\n”, specify it as “\n”.
To search for “\”, specify it as \\\\; this is because the
backslashes are stripped once by the parser and again when the pattern
match is made, leaving a single backslash to be matched against.
Fiddle http://sqlfiddle.com/#!9/ac46b/9
I'm trying to write a MySQL query to identify first name fields that actually contain initials. The problem is that the query is picking up records that should not match.
I have tested against the POSIX ERE regex implementation in RegEx Buddy to confirm my regex string is correct, but when running in a MySQL query, the results differ.
For example, the query should identify strings such as:
'A.J.D' or 'A J D'.
But it is also matching strings like 'Ralph' or 'Terrance'.
The query:
SELECT *, firstname REGEXP '^[a-zA-z]{1}(([[:space:]]|\.)+[a-zA-z]{1})+([[:space:]]|\.)?$' FROM test_table
The 'firstname' field here is VARCHAR 255 if that's relevant.
I get the same result when running with a string literal rather than table data:
SELECT 'Ralph' REGEXP '^[a-zA-z]{1}(([[:space:]]|\.)+[a-zA-z]{1})+([[:space:]]|\.)?$'
The MySQL documentation warns about potential issues with REGEXP, I'm unsure if this is related to the problem I'm seeing:
Warning The REGEXP and RLIKE operators work in byte-wise fashion, so
they are not multi-byte safe and may produce unexpected results with
multi-byte character sets. In addition, these operators compare
characters by their byte values and accented characters may not
compare as equal even if a given collation treats them as equal.
Thanks in advance.
If you're testing this in the mysql client, you need to escape the backslashes. Each occurence of \. must turn into \\. This is necessary because your input is first processed by the mysql client, which turns \. into .. So you need to make it keep the backslashes by escaping them.
I've been trying to get a table row with this query:
SELECT * FROM `table` WHERE `field` LIKE "%\u0435\u0442\u043e\u0442%"
Field itself:
Field
--------------------------------------------------------------------
\u0435\u0442\u043e\u0442 \u0442\u0435\u043a\u0441\u0442 \u043d\u0430
Although I can't seem to get it working properly.
I've already tried experimenting with the backslash character:
LIKE "%\\u0435\\u0442\\u043e\\u0442%"
LIKE "%\\\\u0435\\\\u0442\\\\u043e\\\\u0442%"
But none of them seems to work, as well.
I'd appreciate if someone could give a hint as to what I'm doing wrong.
Thanks in advance!
EDIT
Problem solved.
Solution: even after correcting the syntax of the query, it didn't return any results. After making the field BINARY the query started working.
As documented under String Comparison Functions:
Note
Because MySQL uses C escape syntax in strings (for example, “\n” to represent a newline character), you must double any “\” that you use in LIKE strings. For example, to search for “\n”, specify it as “\\n”. To search for “\”, specify it as “\\\\”; this is because the backslashes are stripped once by the parser and again when the pattern match is made, leaving a single backslash to be matched against.
Therefore:
SELECT * FROM `table` WHERE `field` LIKE '%\\\\u0435\\\\u0442\\\\u043e\\\\u0442%'
See it on sqlfiddle.
it can be useful for those who use PHP, and it works for me
$where[] = 'organizer_info LIKE(CONCAT("%", :organizer, "%"))';
$bind['organizer'] = str_replace('"', '', quotemeta(json_encode($orgNameString)));
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.