I need help for this problem.
In MYSQL Table i have a field :
Field : artist_list
Values : 1,5,3,401
I need to find all records for artist uid 401
I do this
SELECT uid FROM tbl WHERE artist_list IN ('401');
I have all record where artist_list fields values are '401' only, but if i have 11,401 this query do not match.
Any idea ?
(I cant user LIKE method because if artist uid is 3 (match for 30, 33, 3333)...
Short Term Solution
Use the FIND_IN_SET function:
SELECT uid
FROM tbl
WHERE FIND_IN_SET('401', artist_list) > 0
Long Term Solution
Normalize your data - this appears to be a many-to-many relationship already involving two tables. The comma separated list needs to be turned into a table of it's own:
ARTIST_LIST
artist_id (primary key, foreign key to ARTIST)
uid (primary key, foreign key to TBL)
Your database organization is a problem; you need to normalize it. Rather than having one row with a comma-separated list of values, you should do one value per row:
uid artist
1 401
1 11
1 5
2 5
2 4
2 2
Then you can query:
SELECT uid
FROM table
WHERE artist = 401
You should also look into database normalization because what you have is just going to cause more and more problems in the future.
SELECT uid
FROM tbl
WHERE CONCAT(',', artist_list, ',') LIKE '%,401,%'
Although it would make more sense to normalise your data properly in the first place. Then your query would become trivial and have much better performance.
Related
I need your help.
I have a table like this:
So I want to search for a specific thread. I have two user_id values and I want the rows returned where the user_id is one of the two and the thread_id is the same.
Let's say, Johnny(1) has a thread with Mark(2). Now I know Johny and Mark but I want to get the thread_id of the thread they have in common.
I'd appreciate a SQL hint, but if you know Laravel and Eloquent, that would be even better.
In SQL:
SELECT thread_id
FROM mytable
WHERE user_id IN (1, 2)
GROUP BY thread_id
HAVING COUNT(DISTINCT user_id) = 2
I have a query regarding regular expression.I have design a table which contain three column one column contain member ids which are separated by commas.I am showing you my table structure.Please follow
send_id member_id
1 1211,23,34
2 1,23
I want to select only send_id 2 data which contain member_id as 1.
this is the query that i am using
SELECT * FROM table WHERE column REGEXP '^[1]+$';
but this query giving me both row.Please help me.
With Regards
Rahul
Never store separate values in one column
Normalize your structure like
send_id member_id
1 1211
1 23
1 34
2 1
2 23
If you still want your regex, then it will be
SELECT * FROM t WHERE column REGEXP '(^|[^0-9])1([^0-9]|$)'
First, you should be normalizing your data so you're not in this horrible mess in the first place. Here's a good resource explaining normalization.
Second, I believe your problem lies with your regular expression. Try this instead:
SELECT * FROM table WHERE column REGEXP '^[1]$';
The regular expression you're using uses the [1]+ group. The + means it has to match [1] 1 or more times, hence why you're getting two rows instead of one. Removing the + means it will match [1] once.
However, that still won't fix your problem, as more than one row contains 1. This is why normalization is so important.
Having multiple values inside a column isn't a good practice for designing a DB.
You should normalize your data, i.e., put just one piece of atomic information inside each element of your table.
You can find more information regarding to this in Wikipedia:
http://en.wikipedia.org/wiki/Database_normalization
Like they have told you, perfect solution would be normalize your data, I think Alma Do Mundo answer explains it quite well.
If you want to use REGEXP anyway you have to take in account four approaches; id is the only one, id is the first, id is in the middle and id is at the end. I have use id=74 for the example:
SELECT * FROM table WHERE member_id REGEXP '(^74$|^74,|,74,|,74$)';
depending on your requirements, you should either normalize your data i.e. make 3 tables, one with the send ID, one with the member id, and one that combines the two, then you can link them up with INNER JOINS.
However, if you are going to do it that way, you can use a "WHERE member_id LIKE %1%" to pull in all the relevant fields. You'll have to use the application to filter the relevant records.
In any case, if you're not going to normalize the data you will have to use the front end to filter out the results.
An example of the inner join syntax would look like this
SELECT * FROM SendTable
JOIN Send_Member ON SendTable.send_id = Send_Member.send_id
JOIN Member ON Member.member_id = Send_Member.member_id
WHERE Member.member_id = 1;
where the schema looks like:
Sendtable:
send_Id (primary key)
...other fields
Send_Member:
send_id (primary key and foreign key to SendTable)
member_id (primary key and foreign key to member)
...any fields you might want that are relevant to the particular send table and member table link
Member:
member_id (primarykey)
...other fields
I am quite new to PHP and MySQL, but have experience of VBA and C++. In short, I am trying to count the occurrences of a value (text string), which can appear in 11 columns in my table.
I think I will need to populate a single-dimensional array from this table, but the table has 14 columns (named 'player1' to 'player14'). I want each of these 'players' to be entered into the one-dimensional array (if not NULL), before proceeding to the next row.
I know there is the SELECT DISTINCT statement in MySQL, but can I use this to count distinct occurrences across 14 columns?
For background, I am building a football results database, where player1 to player14 are the starting 11 (and 3 subs), and my PHP code will count the number of times a player has made an appearance.
Thanks for all your help!
Matt.
Rethink your database schema. Try this:
Table players:
player_id
name
Table games:
game_id
Table appearances:
appearance_id
player_id
game_id
This reduces the amount of duplicate data. Read up on normalization. It allows you to do a simple select count(*) from appearances inner join players on player_id where name='Joe Schmoe'
First of all, the database schema you're using is terrible, and you just found out a reason why.
That being said, I see no other way then to first get a list of all players by distinctly selecting the names of players into an array. Before each insertion, you would have to check if the name is already in the array (if it is already in, don't add it again).
Then, when you have the list of names, you would have to run an SQL statement for each player, adding up the number of occurences, like so:
SELECT COUNT(*)
FROM <Table>
WHERE player1=? OR player2=? OR player3=? OR ... OR player14 = ?
That is all pretty complicated, and as I said, you should really change your database schema.
This sounds like a job for fetch_assoc (http://php.net/manual/de/mysqli-result.fetch-assoc.php).
If you use mysqli, you would get each row as an associative array.
On the other hand the table design seems a bit flawed, as suggested before.
If you had on table team with team name and what not and one table player with player names.
TEAM
| id | name | founded | foo |
PLAYER
| id | team_id | name | bar |
With that structure you could add 14 players, which point at the same team and by joining the two tables, extract the players that match your search.
I have a table with three fields - userID, couponID, last_couponID.
When the user accesses a coupon, I run this query:
mysql_query("INSERT INTO users_coupons (userID, couponID) VALUES ('$recordUserID', '$recordCoupID')");
Further, I have another query that should insert the last couponID into the field last_couponID, by polling the database table and finding the most recent result for the current userID.
I believe it is as such:
SELECT couponID FROM users_coupons ORDER BY userID LIMIT 1
Am I correct? Or should I use a different query?
Like this:
userID couponID
1 3
1 13
1 23
2 5
2 3
So if I wanted userID 2's latest coupon, it'd be '3', and for userID 1, it'd be '23'. I just want the last entry in the database table where the userID matches a value I provide.
I would just add a primary key (autoincrementing) to the users_coupons table.
When you want the latest coupon of a user,SELECT couponID FROM users_coupons WHERE userID = ? ORDER BY id DESC LIMIT 1
Assuming that couponID is numeric, and the last couponID for a certain userId is the greatest (as a number), you can do:
SELECT MAX(couponID) AS lastCouponId FROM users_coupons WHERE userId = <put here the user id>
EDIT: since you've edited your question, I edit my answer.
You have to add an auto-increment primary key, otherwise you can't know exactly which entry is the last one. When I answered, I supposed the last coupon for a certain userId was the one with the greatest couponId. Are you sure you can't just make things work this way?
Something along the lines of...
SELECT couponID
FROM users_coupons
WHERE userID = <current user id>
ORDER BY <primary key of user_coupons table if it's an identity column> DESC
LIMIT 1
...is more appropriate. Your query as it stands doesn't do anything with the 'current' user ID.
If you are actually after the highest couponID then SELECT MAX(couponID)... as suggested by Giacomo is a good idea - coupled with a check for the UserID matching the current user ID.
#Giacomo's answer is valid if you are incrementing the CouponID reliably as an identifier. If you have merged in data or are adjusting this value any other way then it may not be correct.
In theory, if you consider CouponID to be a surrogate key then you cannot use it to explicitly determine insert order. If you intend for it to be used for the purpose of insert order then you also need to make sure your supporting code and DB maintenance plans promote this use.
I contend that the "correct" method is to also store a DateTime
In cases when some one needs to store more than one value in a in a cell, what approach is more desirable and advisable, storing it with delimiters or glue and exploding it into an array later for processing in the server side language of choice, for example.
$returnedFromDB = "159|160|161|162|163|164|165";
$myIdArray = explode("|",$returnedFromDB);
or as a JSON or PHP serialized array, like this.
:6:{i:0;i:1;i:1;i:2;i:2;i:3;i:3;i:4;i:4;i:5;i:5;i:6;}
then later unserialize it into an array and work with it,
OR
have a new row for every new entry like this
postid 12 | showto 2
postid 12 | showto 3
postid 12 | showto 5
postid 12 | showto 6
postid 12 | showto 8
instead of postid 12 | showto "2|3|4|6|8|5|".
OR postid 12 | showto ":6:{i:0;i:2;i:1;i:3;i:2;i:3;i:3;i:4;i:4;i:5;i:5;i:6;}".
Thanks, looking forward to your opinions :D
In cases when some one needs to store more than one value in a in a cell, what approach is more desirable and advisable, storing it with delimiters or glue and exploding it into an array later for processing in the server side language of choice, for example.
Neither. Oh goodness, neither! Edgar F. Codd is rolling in his grave right now.
Storing delimited data in a text field is no better than storing it in a flat file. The data becomes unqueryable. Storing PHP serialized data in a text field is even worse because then only PHP can parse the data.
You want a nice, happy, normalized database.
The thing you're trying to describe is a many-to-many relationship. Each user can maintain one or more posts. Likewise, each post can be maintained by one or more user. Right? Then something like this will work.
CREATE TABLE users (
user_id INTEGER PRIMARY KEY,
...
);
CREATE TABLE posts (
post_id INTEGER PRIMARY KEY,
...
);
CREATE TABLE user_posts (
user_id INTEGER REFERENCES users(user_id),
post_id INTEGER REFERENCES posts(post_id),
UNIQUE KEY(user_id, post_id)
);
-- All posts made by user 22.
SELECT posts.*
FROM posts, user_posts
WHERE user_posts.user_id = 22
AND posts.post_id = user_posts.post_id
-- All users that worked on post 47
SELECT users.*
FROM users, user_posts
WHERE user_posts.post_id = 47
AND users.user_id = user_posts.user_id
Most of the time the recommendation is that many-to-many relationships (such as posts to users) should have a mapping table with 1 row for each post-user combination (in other words, your "new row for every new entry" version).
It's more optimal for things like join queries, and lets you retrieve only the data you need.
You should only serialize data in the DB if the data is never needed to be processed by the DB. For example, you could serialize user ID in the user_id field if you never need to do a query with the user_id field; e.g. never selecting anything based on user.
If these are posts (blog/news/etc. posts?) then I'm pretty confident you'll need to be able to query them by user. Normalizing the user into another table would serve you:
CREATE TABLE posts (post_id, ....);
CREATE TABLE post_users (post_id, user_id, ...);
You can then get the users in a different query, or use group_concat: SELECT post_id, GROUP_CONCAT(user_id) FROM posts JOIN post_users USING (post_id) GROUP BY post_id. When you need to show user name, just join to the users table to get their name in the group concat.
From RDBMS point of view i would 'have a new row for every new entry'
Thats called m:n relationship table.
You can then query the data however you like.
If you need postid 12 | showto ":6:{i:0;i:2;i:1;i:3;i:2;i:3;i:3;i:4;i:4;i:5;i:5;i:6;}". you can do
SELECT postid, CONCAT(':',count(showto),':{i:',GROUP_CONCAT(showto SEPARATOR ';i:'),';}') AS showto
FROM tablename
GROUP BY postid
However if you only need the data in 1 form and not do any other kind of queries on that data then you may aswell store the string.