I need to search value starting with given string in comma separated values.
Example,
I have '1_2_3_4_5_6, 1_2_3_4_5_8, 1_2_3_6_5_8' in my column. I can search for rows with exact value using
select * from table where find_in_set('1_2_3_4_5_6',column)
But how to search, if starting part of the string is given? something like this:
select * from table where find_in_set('1_2_3%',column) ?
If I understand you correctly (I'm still not sure I do), you could just use:
SELECT * FROM table WHERE column LIKE '%1_2_3%';
This would give you columns where the value is like:
1_2_3_4_5_5
1_4_5_, 1_2_3_4_5_, 6_7
and so on.
But you should really normalize your tables. This is important for good queries and performance wise also important.
According to #Xatenev suggestions, if you really like only the values and the row of each matching row, this won't work so well and will be a lot of overhead. This are the steps that I would perform:
Split all CSV columns into multiple rows (this is a hack and a performance killer, I found some working solution but did not test it, see here): Pseudo Code: SELECT ID, SPLIT(',', column) AS entries FROM table (NOT WORKING)
Filter the new virtual table to select only rows that match the prefix (SELECT * FROM virtual_table WHERE find_in_set("1_2_3%, entries) ORDER BY ID)
Concatenate the matching entries back into a list for each ID. e.g. SELECT ID, GROUP_CONCAT(entries SEPARATOR ', ') FROM filtered_table GROUP BY ID
Do something
The unknown part is the beginning with the split in multiple rows. There are a lot of possible solutions all with their own drawbacks or advantages. Be aware that this will always (regardless of the selected method) will cost a lot of performance.
ADDITIONAL NODE:
It could be adventures in your situation, that you get each row matching your search string like in my first example and filter them in memory. This might be faster than doing this in MYSQL.
you can try with 'REGEXP'
If you want to match data with subtring, please try this
SELECT * FROM `table` WHERE `column` REGEXP '[, ]?1_2_3[^,]*,?' ;
Or
If you want to exact start match, please try this
SELECT * FROM `table` WHERE `column` REGEXP '[, ]?1_2_3[^,]*,?' AND `column` NOT REGEXP '[^, ]1_2_3[^,]*,?' ;
I was able to solve it with no-regex. Sonam's Answer is correct as well.
SELECT * from table WHERE CONCAT(',', columnname, ',') like '%,1_2_3%'
I am hoping to run a mysql_query where I can select a row if a certain field ends in a number. For example:
<?php
$query = mysql_query("SELECT id FROM table WHERE [ID ENDS IN 0]");
$query = mysql_query("SELECT id FROM table WHERE [ID ENDS IN 1]");
$query = mysql_query("SELECT id FROM table WHERE [ID ENDS IN 2]");
$query = mysql_query("SELECT id FROM table WHERE [ID ENDS IN 3]");
//and so on...
?>
Is there a way to do this? Any help would be great. Thank you!
SELECT ...
WHERE somefield LIKE '%1'
SELECT id FROM table WHERE mod(id, 10) = 1
give it a go
SELECT id
FROM table
WHERE id LIKE '%0'
You can use regular expressions if you need to find if field is ending in a number or not as follows
SELECT id FROM table WHERE id REGEXP '[0-9]$'
Hope it helps...
You could do it with a cast and LIKE, but the performance is likely to be terrible for any non-trivial amount of data (I've not tested in your particular case, but in my experience, casting to string so you can use string operations really slows a query down).
A better way would be to use modulus.
For example, to get all the rows where the numerical field ends in a 4:
SELECT *
FROM table
WHERE MOD(column_of_interest, 10) = 4
Again, I've not benchmarked this, but it's probably going to perform better than casting would.
Of course, if the column type is already a string, then LIKE is the way to go, as using MOD on strings would also require a cast.
You can use LIKE and a wild card expression
it should be somthing like
SELECT id FROM table WHERE id REGEX '%0$'
SELECT id FROM table WHERE id REGEX '%1$'
and so on.
SELECT id FROM table WHERE id REGEXP '1[[:>:]]'
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,%';
Let's say I have table with column 'URL' whrere I store urls like this
one/two
one/two/three
alpha/omega
And I want to get data from database for specific url and if it is not found I remove the last part of url and search again:
Example:
I have url like one/two/three/four/five.
I do search for "one/two/three/four/five"
if not found search again for "one/two/three/four"
if not found search again for "one/two/three"
if not found search again for "one/two"
I would like to have something like:
SELECT * FROM db WHERE url=one/two/three/four/five
UNION
SELECT * FROM db WHERE url=one/two/three/four/five
UNION
SELECT * FROM db WHERE url=one/two/three/four
UNION
SELECT * FROM db WHERE url=one/two/three
UNION
SELECT * FROM db WHERE url=one/two
UNION
SELECT * FROM db WHERE url=one
but I want to stop searching if the row is found.
Is this possible or do I have to do it with separated queries.
Thanks for help.
I thing that this is the most elegant approach to your question. This statement is independent depth path and you don't need to split constant url in subsequent selects:
SELECT
*
FROM
db
WHERE
concat( 'one/two/three/four/five' , '/') like concat( url , '/%')
ORDER BY
LENGTH (url) desc
LIMIT 1
I have tested this query in MySQL, also you can check it! (in MSSQL syntax)
Just replace UNION with UNION ALL and add LIMIT 1 at the end.
P.S. UNION ALL would not make much difference in this particular example, but it is useful to know the difference: http://www.mysqlperformanceblog.com/2007/10/05/union-vs-union-all-performance/
Let's say I have table with column 'URL' whrere I store urls like this
one/two
one/two/three
alpha/omega
Don't do that, it's a horrible design and the proof is the problem you are having running such a simple query; store each URl on a DIFFERENT ROW. Read up on Normalization.
You could use a regexp to search in a single query, but it'll get you all rows:
SELECT * FROM db WHERE url REGEXP "^one((/two)|(/two/three)|(two/three/four)|(/two/three/four/five))?$"
so if you only want the results from the first WHERE you'll have to do multiple queries.
If you really want to have a single query and don't care about a little overhead in the search you could do
SELECT * FROM db WHERE url REGEXP "^one((/two)|(/two/three)|(two/three/four)|(/two/three/four/five))?$" ORDER BY length(url) DESC LIMIT 1
This will get you the first possible result only, but the query inside will have to get all possible results first -> less efficient, but more compact.
I hope this helps!