I'm attempting to query our database to find specific types of transactions with unique parameters.
There are multiple formats and I'm looking to get the transactions with the -Q/ parameter.
BCR*DEVSTS
BCR*1150
BCR*1150/28AUG
BCR*DEVSTS-Q/28AUG
BCR*DEV-Q/28AUG
I'm able to find the BCR transactions but due to memory constraints I can only get the first 10k rows and they don't have the -Q/ parameter. I'm trying to create a query that will only select the required transactions.
I used the following to query for the basis transaction:
select *
from transaction_200827
where reqresponse= 'Q' and message rlike '^BCR.*'
I've reviewed multiple websites but haven't been able to find an example of this scenario. I've tried variations on the examples provided and haven't been successful:
select * from transaction_200827 where reqresponse= 'Q' and message rlike '^BCR(Q/).*'
select * from transaction_200827 where reqresponse= 'Q' and message rlike '^BCR%Q/%.*'
I'm fairly new to building queries and would appreciate any guidance or direction for generating this type of query.
You're mixing regexp and LIKE patterns. Use either
message LIKE 'BCR%-Q/%'
or
message RLIKE '^BCR.*-Q/'
You're also missing the - before Q in your patterns.
There's no need to add .* to the end of the regexp -- RLIKE succeeds when the regexp matches anywhere in the string, it doesn't have to match the entire string (the ^ anchor forces it to match starting from the beginning, but there's no $ anchor extending it to the end).
If the column has an index, I recommend using LIKE -- in my experience, RLIKE doesn't take advantage of indexes. Either way, the index will only be used for matching the BCR at the beginning, the rest requires scanning all the values with that prefix.
Related
I have a table which store some datas. This is my table structure.
Course
Location
Wolden
New York
Sertigo
Seatlle
Monad
Chicago
Donner
Texas
I want to search from that table for example with this keyword Sertigo Seattle and it will return row number two as a result.
I have this query but doesn't work.
SELECT * FROM courses_data a WHERE CONCAT_WS(' ', a.Courses, a.Location) LIKE '%Sertigo Seattle%'
Maybe anyone knows how to make query to achieve my needs?
If you want to search against the course and location then use:
SELECT *
FROM courses_data
WHERE Course = 'Sertigo' AND Location = 'Seattle';
Efficient searching is usually implemented by preparing the search string before running the actual search:
You split the search string "Sertigo Seattle" into two words: "Sertigo" and "Seattle". You trim those words (remove enclosing white space characters). You might also want to normalize the words, perhaps convert them to all lower case to implement a case insentive search.
Then you run a search for the discrete words:
SELECT *
FROM courses_data
WHERE
(Course = 'Sertigo' AND Location = 'Seattle')
OR
(Course = 'Seattle' AND Location = 'Sertigo');
Of course that query is created using a prepared statement and parameter binding, using the extracted and trimmed words as dynamic parameters.
This is is much more efficient than using wildcard based search with the LIKE operator. Because the database engine can make use of the indexes you (hopefully) created for that table. You can check that by using EXPLAIN feature MySQL offers.
Also it does make sense to measure performance: run different search approaches in a loop, say 1000 times, and take the required time. You will get a clear and meaningful example. Also monitoring CPU and memory usage in such a test is of interest.
I am not a seasonal Windows user, I got a task wherein I had to query the Window Index search table i.e "Systemindex" for fetching some user specific data from the db.
And for this I have to match a pattern basically a regular expression while fetching the data.
SELECT System.FileName, System.ItemPathDisplay, System.DateCreated, System.DateModified, System.ItemName, System.KindText FROM Systemindex WHERE Contains('“(?=^[A-Za-z\d!##\$%\^&\*\(\)_\+=]{9,32}$)”');
The above would allow us to search for say stored passwords.
But when I query the db using the below command I was getting an error. And later I came to know that the "contains" clause
does not support regular expression. Is there an alternative to achieve this?
there is REGEXP operator http://dev.mysql.com/doc/refman/5.7/en/regexp.html,
use smth like this
SELECT * FROM Systemindex WHERE some_column REGEXP 'your_regex'
I am trying to retrieve a list of database records which have specific 'interest codes' inside of the 'custom_fields' table. So for example right now there is 100 records, I need the Name, Email and Interest Code from each of those records.
I've tried with the following statement:
SELECT * FROM `subscribers` WHERE list = '27' AND custom_fields LIKE 'CV'
But with no luck, the response was:
MySQL returned an empty result set (i.e. zero rows). ( Query took 0.0003 sec )
You can see in this screenshot that at-least two rows have 'CV' inside custom_fields. Whilst within the database it's not called 'Interest Code', that's what they are so therefore why I am referencing it in this way.
You need to enclose your "search string" inside some wildcards:
select * from subscribers where list=27 and custom_fields like '%CV%';
The % wildcard means "zero or more chacarcters at this position". The "_" wildcard means "a character in this position". Please read the reference manual on the topic. Also, you may want to read about regular expressions in MySQL for more complex string comparissons.
I have the following query :
SELECT * FROM `user`
WHERE MATCH (user_login) AGAINST ('supriya*' IN BOOLEAN MODE)
Which outputs all the records starting with 'supriya'.
Now I want something that will find all the records ending with e.g. 'abc'.
I know that * cannot be preappended and it doesn't work either and I have searched a lot but couldn't find anything regarding this.
If I give query the string priya ..it should return all records ending with priya.
How do I do this?
Match doesn't work with starting wildcards, so matching with *abc* won't work. You will have to use LIKE to achieve this:
SELECT * FROM user WHERE user_login LIKE '%abc';
This will be very slow however.
If you really need to match for the ending of the string, and you have to do this often while the performance is killing you, a solution would be to create a separate column in which you reverse the strings, so you got:
user_login user_login_rev
xyzabc cbazyx
Then, instead of looking for '%abc', you can look for 'cba%' which is much faster if the column is indexed. And you can again use MATCH if you like to search for 'cba*'. You will just have to reverse the search string as well.
I believe the selection of FULL-TEXT Searching isn't relevant here. If you are interested in searching some fields based on wildcards like:
%word% ( word anywhere in the string)
word% ( starting with word)
%word ( ending with word)
best option is to use LIKE clause as GolezTrol has mentioned.
However, if you are interested in advanced/text based searching, FULL-TEXT search is the option.
Limitations with LIKE:
There are some limitations with this clause. Let suppose you use something like '%good' (anything ending with good). It may return irrelevant results like goods, goody.
So make sure you understand what you are doing and what is required.
I am trying to follow: http://dev.mysql.com/doc/refman/4.1/en/fulltext-natural-language.html
in an attempt to improve search queries, both in speed and the ability to order by score.
However when using this SQL ("skitt" is used as a search term just so I can try match Skittles).
SELECT
id,name,description,price,image,
MATCH (name,description)
AGAINST ('skitt')
AS score
FROM
products
WHERE
MATCH (name,description)
AGAINST ('skitt')
it returns 0 results. I am trying to find out why, I think I might have set my index's up wrong I'm not sure, this is the first time I've strayed away from LIKE!
Here is my table structure and data:
Thank you!
By default certain words are excluded from the search. These are called stopwords. "a" is an example of a stopword. You could test your query by using a word that is not a stopword, or you can disable stopwords:
How can I write full search index query which will not consider any stopwords?
If you want to also match prefixes use the truncation operator in boolean mode:
*
The asterisk serves as the truncation (or wildcard) operator. Unlike the other operators, it should be appended to the word to be affected. Words match if they begin with the word preceding the * operator.