I must use this format where A operand B. A is the field; I want B to be either "text 1" or "text 2", so if A has data like "text 1 texttext" or "texttext 2" , the query will have result.
But how do I write this? Does MySQL support something like
where A contains ('text 1' OR 'text 2')? `
Two options:
Use the LIKE keyword, along with percent signs in the string
select * from table where field like '%a%' or field like '%b%'.
(note: If your search string contains percent signs, you'll need to escape them)
If you're looking for more a complex combination of strings than you've specified in your example, you could regular expressions (regex):
See the MySQL manual for more on how to use them: http://dev.mysql.com/doc/refman/5.1/en/regexp.html
Of these, using LIKE is the most usual solution -- it's standard SQL, and in common use. Regex is less commonly used but much more powerful.
Note that whichever option you go with, you need to be aware of possible performance implications. Searching for sub-strings like this will mean that the query will have to scan the entire table. If you have a large table, this could make for a very slow query, and no amount of indexing is going to help.
If this is an issue for you, and you'r going to need to search for the same things over and over, you may prefer to do something like adding a flag field to the table which specifies that the string field contains the relevant sub-strings. If you keep this flag field up-to-date when you insert of update a record, you could simply query the flag when you want to search. This can be indexed, and would make your query much much quicker. Whether it's worth the effort to do that is up to you, it'll depend on how bad the performance is using LIKE.
You can write your query like so:
SELECT * FROM MyTable WHERE (A LIKE '%text1%' OR A LIKE '%text2%')
The % is a wildcard, meaning that it searches for all rows where column A contains either text1 or text2
I've used most of the times the LIKE option and it works just fine.
I just like to share one of my latest experiences where I used INSTR function. Regardless of the reasons that made me consider this options, what's important here is that the use is similar:
instr(A, 'text 1') > 0 or instr(A, 'text 2') > 0
Another option could be:
(instr(A, 'text 1') + instr(A, 'text 2')) > 0
I'd go with the LIKE '%text1%' OR LIKE '%text2%' option... if not hope this other option helps
I user for searching the size of motorcycle :
For example :
Data = "Tire cycle size 70 / 90 - 16"
i can search with "70 90 16"
$searchTerms = preg_split("/[\s,-\/?!]+/", $itemName);
foreach ($searchTerms as $term) {
$term = trim($term);
if (!empty($term)) {
$searchTermBits[] = "name LIKE '%$term%'";
}
}
$query = "SELECT * FROM item WHERE " .implode(' AND ', $searchTermBits);
Related
I have a table where a field can have single quotes, but I need to be able to search by that field without single quotes. For example, if the search query is "Johns favorite", I need to be able to find a row where that field contains "John's favorite". I was looking into regex for it, but that seems to return a 0 or 1 when used in a select statement, if I'm understanding it correctly.
Take a look at:
http://www.artfulsoftware.com/infotree/queries.php#552
This will give you the distance between two strings. I.e. you can check whether levensthein distance is less than 3, which means, less than 3 operations are required to be equal.
Try using REPLACE:
SELECT
IF(
REPLACE("John's favorite","'","") = "Johns favorite" ,
"found",
"not found"
)
It's not optimal but it should do the job.
My user table has a column "name" which contains information like this:
Joe Lee
Angela White
I want to search for either first name or last name efficiently. First name is easy, I can do
SELECT * FROM user WHERE name LIKE "ABC%"
But for last name, if I do
SELECT * FROM user WHERE name LIKE "%ABC"
That would be extremely slow.
So I am thinking about counting the characters of the input, for example, "ABC" has 3 characters, and if I can search only the last three characters in name column, that would be great. So I want something like
SELECT * FROM user WHERE substring(name, end-3, end) LIKE "ABC%"
Is there anything in MySQL that can do this?
Thanks so much!
PS. I cannot do fulltext because our search engine doesn't support that.
The reason that
WHERE name LIKE '%ith'
is a slow way to look for 'John Smith' by last name is the same reason that
WHERE Right(name, InStr(name, ' ' )) LIKE 'smi%'
or any other expression on the column is slow. It defeats the use of the index for quick lookup and leaves the MySQL server doing a full table scan or full index scan.
If you were using Oracle (that is, if you worked for a formerly wealthy employer) you could use function indexes. As it is you have to add some extra columns or some other helping data to accelerate your search.
Your smartest move is to split your first and last names into separate columns. Several other people have pointed out good reasons for doing that.
If you can't do that you could try creating an extra column which contains the name string reversed, and create an index on that column. That column will have, for example, 'John Smith' stored as 'htimS nhoJ'. Then you can search as follows.
WHERE nameReversed LIKE CONCAT(REVERSE('ith'),'%')
This search will use the index and be decently fast. I've had good success with it.
You're close. In MySQL you should be able to use InStr(str, substr) and Right(str, index) to do the following:
SELECT * FROM user WHERE Right(name, InStr(name, " ")) LIKE "ABC%"
InStr(name, " ") returns the index of the Space character (you may have to play with the " " syntax). This index is then used in the Right() function to search for only the last name (basically; problems arise when you have multiple names, multiple spaces etc). LIKE "ABC%" would then search for a last name starting with ABC.
You cannot use a fixed index as names that are more than 3 or less than 3 characters long would not return properly as you suggest.
However, as Zane said, it's a much better practise to use seperate fields.
If it is a MyIsam table, you may use Free text search to do the same.
You can use the REGEXP operator:
SELECT * FROM user WHERE name REGEXP "ABC$"
http://dev.mysql.com/doc/refman/5.1/en/regexp.html
I have a mysql table with a list of keywords such as:
id | keywords
---+--------------------------------
1 | apple, oranges, pears
2 | peaches, pineapples, tangerines
I'm trying to figure out how to query this table using an input string of:
John liked to eat apples
Is there a mysql query type that can query a field with a sentence and return results (in my example, record #1)?
One way to do it could be to convert apple, oranges, pears to apple|oranges|pears and use RLIKE (ie regular expression) to match against it.
For example, 'John liked to eat apples' matches the regex 'apple|orange|pears'.
First, to convert 'apple, oranges, pears' to the regex form, replace all ', ' by '|' using REPLACE. Then use RLIKE to select the keyword entries that match:
SELECT *
FROM keywords_table
WHERE 'John liked to eat apples' RLIKE REPLACE(keywords,', ','|');
However this does depend on your comma-separation being consistent (i.e. if there is one row that looks like apples,oranges this won't work as the REPLACE replaces a comma followed by a space (as per your example rows).
I also don't think it'll scale up very well.
And, if you have a sentence like 'John liked to eat pineapples', it would match both of the rows above (as it does have 'apple' in it). You could then try to add word boundaries to the regex (i.e. WHERE $sentence RLIKE '[[:<:]](apple|oranges|pears)[[:>:]]'), but this would screw up matching when you have plurals ('apples' wouldn't match '[wordboundary]apple[wordboundary]').
Hopefully this isn't more abstract than what you need but maybe good way of doing it.
I haven't tested this but I think it would work. If you can use PHP you can use str_replace to turn the spaces into keyword LIKE '%apple%'
$sentence = "John liked to eat apples";
$sqlversion = str_replace(" ","%' OR Keyword like '%",$sentence );
$finalsql = "%".$sqlversion."%";
the above will echo:
%John%' OR Keyword like '%liked%' OR Keyword like '%to%' OR Keyword like '%eat%' OR Keyword like '%apples%
Then just combine with your SQl statement
SQL ="SELECT *
FROM keywords_table
WHERE Keyword like" . $finalsql;
Storing comma delimited data is... less than ideal.
If you broke up the string "John liked to eat apples" into individual words, you could use the FIND_IN_SET operator:
WHERE FIND_IN_SET('apple', t.keywords) > 0
The performance wouldn't be great - this operation is better suited to Full Text Search.
I'm not aware of any direct solution to that type of query. But Full Text Search is a possibility. If you have a full-text index on the field of interest then a search with OR between each word in the sentence (although I think the OR operator is implied) would find that record ... but it might also find more than you want too.
I really don't think what you are looking for is completely possible but you can look into Full Text Search or SOUNDEX. SOUNDEX, for example, can do something like:
WHERE SOUNDEX(sentence) = SOUNDEX('%'+keywords+'%');
I have never tried it in this context but you should and let me know how it works out.
I've to ask your help to solve this problem.
My website has a search field, let's say user writes in "Korg X 50"
In my database in table "products" i have a filed "name" that holds "X50" and a field "brand" that hold "Korg". Is there a way to use the UNION option to get the correct record ?
And if the user enters "Korg X-50" ?
Thank you very much !
Matteo
May be you should use full-text search
SELECT brand, name, MATCH (brand,name) AGAINST ('Korg X 50') AS score
FROM products WHERE MATCH (brand,name) AGAINST ('Korg X 50')
As far as I understand you don't need UNION but something like
SELECT * FROM table1
WHERE CONCAT(field1, field2) LIKE '%your_string%'
On client side you get rid of all characters (like space, hyphen, etc) in your_string that appears in user input and cannot be in field1 or field2.
So, user input Korg X 50 as well as Korg X-50 becomes KorgX50.
you will need to get some form of searchable text.
either parse out the input for multiple key words and match each separately, or perhaps try to append them all together and match to the columns appended in the same way.
you will also need either a regex, or maybe a simpler search and replace to get rid of spaces and dashes after the append before the comparison.
in general, allowing users to search for open ended text strings is more complicated than 'what union do i use'... you will ideally also be worried about slight misspellings and capitalization, and keyword order.
you may consider pulling all keywords out from your normal record into a separate keyword list associated with each product, then use that list to perform your searches.
If you do not want to parse user input and use as it is, then you will need to use a query like this
select * from products where concat_ws(' ',brand,name) = user_input -- or
select * from products where concat_ws(' ',brand,name) like %user_input%
However, this query won't return result if user enters name "Korg X-50" and your table contains "Korg" and "X50", then you need to do some other thing to achive this. You may look at http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_soundex however it won't be a complete solution. Look for text indexing libraries for that ex: lucene
I have an InnoDB database table of 12 character codes which often need to be entered by a user.
Occasionally, a user will enter the code incorrectly (for example typing a lower case L instead of a 1 etc).
I'm trying to write a query that will find similar codes to the one they have entered but using LIKE '%code%' gives me way too many results, many of which contain only one matching character.
Is there a way to perform a more detailed check?
Edit - Case sensitive not required.
Any advice appreciated.
Thanks.
Have a look at soundex. Commonly misspelled strings have the same soundex code, so you can query for:
where soundex(Code) like soundex(UserInput)
use without wildcard % for that
SELECT `code` FROM table where code LIKE 'user_input'
thi wil also check the space
SELECT 'a' = 'a ', return 1 whereas SELCET 'a' LIKE 'a ' return 0
reference