I have a column in one of my table where I store multiple ids seperated by comma's.
Is there a way in which I can use this column's value in the "IN" clause of a query.
The column(city) has values like 6,7,8,16,21,2
I need to use as
select * from table where e_ID in (Select city from locations where e_Id=?)
I am satisfied with Crozin's answer, but I am open to suggestions, views and options.
Feel free to share your views.
Building on the FIND_IN_SET() example from #Jeremy Smith, you can do it with a join so you don't have to run a subquery.
SELECT * FROM table t
JOIN locations l ON FIND_IN_SET(t.e_ID, l.city) > 0
WHERE l.e_ID = ?
This is known to perform very poorly, since it has to do table-scans, evaluating the FIND_IN_SET() function for every combination of rows in table and locations. It cannot make use of an index, and there's no way to improve it.
I know you said you are trying to make the best of a bad database design, but you must understand just how drastically bad this is.
Explanation: Suppose I were to ask you to look up everyone in a telephone book whose first, middle, or last initial is "J." There's no way the sorted order of the book helps in this case, since you have to scan every single page anyway.
The LIKE solution given by #fthiella has a similar problem with regards to performance. It cannot be indexed.
Also see my answer to Is storing a delimited list in a database column really that bad? for other pitfalls of this way of storing denormalized data.
If you can create a supplementary table to store an index, you can map the locations to each entry in the city list:
CREATE TABLE location2city (
location INT,
city INT,
PRIMARY KEY (location, city)
);
Assuming you have a lookup table for all possible cities (not just those mentioned in the table) you can bear the inefficiency one time to produce the mapping:
INSERT INTO location2city (location, city)
SELECT l.e_ID, c.e_ID FROM cities c JOIN locations l
ON FIND_IN_SET(c.e_ID, l.city) > 0;
Now you can run a much more efficient query to find entries in your table:
SELECT * FROM location2city l
JOIN table t ON t.e_ID = l.city
WHERE l.e_ID = ?;
This can make use of an index. Now you just need to take care that any INSERT/UPDATE/DELETE of rows in locations also inserts the corresponding mapping rows in location2city.
From MySQL's point of view you're not storing multiple ids separated by comma - you're storing a text value, which has the exact same meaing as "Hello World" or "I like cakes!" - i.e. it doesn't have any meaing.
What you have to do is to create a separated table that will link two objects from the database together. Read more about many-to-many or one-to-many (depending on your requirements) relationships in SQL-based databases.
Rather than use IN on your query, use FIND_IN_SET (docs):
SELECT * FROM table
WHERE 0 < FIND_IN_SET(e_ID, (
SELECT city FROM locations WHERE e_ID=?))
The usual caveats about first form normalization apply (the database shouldn't store multiple values in a single column), but if you're stuck with it, then the above statement should help.
This does not use IN clause, but it should do what you need:
Select *
from table
where
CONCAT(',', (Select city from locations where e_Id=?), ',')
LIKE
CONCAT('%,', e_ID, ',%')
but you have to make sure that e_ID does not contain any commas or any jolly character.
e.g.
CONCAT(',', '6,7,8,16,21,2', ',') returns ',6,7,8,16,21,2,'
e_ID=1 --> ',6,7,8,16,21,2,' LIKE '%,1,%' ? FALSE
e_ID=6 --> ',6,7,8,16,21,2,' LIKE '%,6,%' ? TRUE
e_ID=21 --> ',6,7,8,16,21,2,' LIKE '%,21,%' ? TRUE
e_ID=2 --> ',6,7,8,16,21,2,' LIKE '%,2,%' ? TRUE
e_ID=3 --> ',6,7,8,16,21,2,' LIKE '%,3,%' ? FALSE
etc.
Don't know if this is what you want to accomplish. With MySQL there is feature to concatenate values from a group GROUP_CONCAT
You can try something like this:
select * from table where e_ID in (Select GROUP_CONCAT(city SEPARATOR ',') from locations where e_Id=?)
this one in for oracle ..here string concatenation is done by wm_concat
select * from table where e_ID in (Select wm_concat(city) from locations where e_Id=?)
yes i agree with raheel shan .. in order put this "in" clause we need to make that column into row below code one do that job.
select * from table where to_char(e_ID)
in (
select substr(city,instr(city,',',1,rownum)+1,instr(city,',',1,rownum+1)-instr(city,',',1,rownum)-1) from
(
select ','||WM_CONCAT(city)||',' city,length(WM_CONCAT(city))-length(replace(WM_CONCAT(city),','))+1 CNT from locations where e_Id=? ) TST
,ALL_OBJECTS OBJ where TST.CNT>=rownum
) ;
you should use
FIND_IN_SET Returns position of value in string of comma-separated values
mysql> SELECT FIND_IN_SET('b','a,b,c,d');
-> 2
You need to "SPLIT" the city column values. It will be like:
SELECT *
FROM table
WHERE e_ID IN (SELECT TO_NUMBER(
SPLIT_STR(city /*string*/
, ',' /*delimiter*/
, 1 /*start_position*/
)
)
FROM locations);
You can read more about the MySQL split_str function here: http://blog.fedecarg.com/2009/02/22/mysql-split-string-function/
Also, I have used the TO_NUMBER function of Oracle here. Please replace it with a proper MySQL function.
IN takes rows so taking comma seperated column for search will not do what you want but if you provide data like this ('1','2','3') this will work but you can not save data like this in your field whatever you insert in the column it will take the whole thing as a string.
You can create a prepared statement dynamically like this
set #sql = concat('select * from city where city_id in (',
(select cities from location where location_id = 3),
')');
prepare in_stmt from #sql;
execute in_stmt;
deallocate prepare in_stmt;
Ref: Use a comma-separated string in an IN () in MySQL
Recently I faced the same problem and this is how I resolved it.
It worked for me, hope this is what you were looking for.
select * from table_name t where (select (CONCAT(',',(Select city from locations l where l.e_Id=?),',')) as city_string) LIKE CONCAT('%,',t.e_ID,',%');
Example: It will look like this
select * from table_name t where ',6,7,8,16,21,2,' LIKE '%,2,%';
I try to use a regex with mysql that search boundary words in a json array string but I don't want the regex match words order because I don't know them.
So I started firstly to write my regex on regex101 (https://regex101.com/r/wNVyaZ/1) and then try to convert this one for mysql.
WHERE `Wish`.`services` REGEXP '^([^>].*[[:<:]]Hygiène[[:>:]])([^>].*[[:<:]]Radiothérapie[[:>:]]).+';
WHERE `Wish`.`services` REGEXP '^([^>].*[[:<:]]Hygiène[[:>:]])([^>].*[[:<:]]Andrologie[[:>:]]).+';
In the first query I get result, cause "Hygiène" is before "Radiothérapie" but in the second query "Andrologie" is before "Hygiène" and not after like it written in the query. The problem is that the query is generated automatically with a list of services that are choosen with no order importance and I want to match only boundary words if they exists no matter the order they have.
You can search for words in JSON like the following (I tested on MySQL 5.7):
select * from wish
where json_search(services, 'one', 'Hygiène') is not null
and json_search(services, 'one', 'Andrologie') is not null;
+------------------------------------------------------------+
| services |
+------------------------------------------------------------+
| ["Andrologie", "Angiologie", "Hygiène", "Radiothérapie"] |
+------------------------------------------------------------+
See https://dev.mysql.com/doc/refman/5.7/en/json-search-functions.html#function_json-search
If you can, use the JSON search queries (you need a MySQL with JSON support).
If it's advisable, consider changing the database structure and enter the various "words" as a related table. This would allow you much more powerful (and faster) queries.
JOIN has_service AS hh ON (hh.row_id = id)
JOIN services AS ss ON (hh.service_id = ss.id
AND ss.name IN ('Hygiène', 'Angiologie', ...)
Otherwise, in this context, consider that you're not really doing a regexp search, and you're doing a full table scan anyway (unless MySQL 8.0+ or PerconaDB 5.7+ (not sure) and an index on the full extent of the 'services' column), and several LIKE queries will actually cost you less:
WHERE (services LIKE '%"Hygiène"%'
OR services LIKE '%"Angiologie"%'
...)
or
IF(services LIKE '%"Hygiène"%', 1, 0)
+IF(services LIKE '%"Angiologie"%', 1, 0)
+ ... AS score
HAVING score > 0 -- or score=5 if you want only matches on all full five
ORDER BY score DESC;
Im optimizing my SQL statement to make it faster.
I have a comma seperated list with zipcodes like
1111, 1112,1115,1112 etc etc
Now in my query I want to match if the iput matches 1 of those zipcodes. If so.. then it will return a ID of the object that has all those zipcodes.
But what is the best way to do this now im doing
AND ( loc.loc_zip LIKE '%".$_REQUEST['zip']."%'
Validation of the input will be added ofcourse.. but this is just for testing. But I have tested this and it seems a bit slow.
Is this the best way to do this ?
you should use 'in'
select * from Users where userid in (1,2,3,4,45,6,656)
Edit:
if the ZipCodes are Chars, you can only use in if you separate them by ''
select * from loc where loc.loc_zip in ('1111','1112','1115','1112')
if .$_REQUEST['zip']. has ' ' then->
select * from loc where loc.loc_zip in (.$_REQUEST['zip'].)
if the ZipCodes are int you can use the first statement
Bare in mid you must intersect your list with '' or it wont work
I have a table call objects which there are the columns:
object_id,
name_english(vchar),
name_japanese(vchar),
name_french(vchar),
object_description
for each object.
When a user perform a search, they may enter either english, japanese or french... and my sql statement is:
SELECT
o.object_id,
o.name_english,
o.name_japanese,
o.name_french,
o.object_description
FROM
objects AS o
WHERE
o.name_english LIKE CONCAT('%',:search,'%') OR
o.name_japanese LIKE CONCAT('%',:search,'%') OR
o.name_french LIKE CONCAT('%',:search,'%')
ORDER BY
o.name_english, o.name_japanese, o.name_french ASC
And some of the entries are like:
Tin spoon,
Tin Foil,
Doctor Martin Shoes,
Martini glass,
Cutting board,
Ting Soda.
So, when the user search the word "Tin" it will return all results of these, but instead I just want to return the results which specific include the term "Tin" or displaying the result and rank them by relevance order. How can I achieve that?
Thanks.
You can use MySQL FULLTEXT indices to do that. This requires the MyISAM table type, an index on (name_english, name_japanese, name_french, object_description) or whatever fields you want to search on, and the appropriate use of the MATCH ... AGAINST operator on exactly that set of columns.
See the manual at http://dev.mysql.com/doc/refman/5.5/en/fulltext-search.html, and the examples on the following page http://dev.mysql.com/doc/refman/5.5/en/fulltext-natural-language.html
After running the query above , you will get all sort of results including ones that you are not interested, but you can then use regular expressions on the above results(returned by mysql server) set to filter out what u need.
This should do the trick - you may have to filter out duplicates, but the basic idea is obvious.
SELECT
`object`.`object_id`,
`object`.`name_english`,
`object`.`name_japanese`,
`object`.`name_french`,
`object`.`object_info`, 1 as ranking
FROM `objects` AS `object`
WHERE `object`.`name_english` LIKE CONCAT(:search,'%') OR `object`.`name_japanese` LIKE CONCAT(:search,'%') OR `object`.`name_french` LIKE CONCAT(:search,'%')
union
SELECT
`object`.`object_id`,
`object`.`name_english`,
`object`.`name_japanese`,
`object`.`name_french`,
`object`.`object_info`, 10 as ranking
FROM `objects` AS `object`
WHERE `object`.`name_english` LIKE CONCAT('%',:search,'%') OR `object`.`name_japanese` LIKE CONCAT('%',:search,'%') OR `object`.`name_french` LIKE CONCAT('%',:search,'%')
ORDER BY ranking, `object`.`name_english`, `object`.`name_japanese`, `object`.`name_french` ASC