I'm not sure how to articulate this correctly so here it goes.
I'm designing a small webapp and in my database I have a table for users, commits, and userCommits. it's pretty minimal as in users has an ID that is auto number as well as commitshas a similar ID column. Now userCommits is what links them together as you can see in the following figure.
What I've done is INSERT INTO commits (...) VALUES (...) but the problem with that is how do I create the link in userCommits so that userCommits.commitID will equal the correct commit. I feel like I shouldn't just query the table to find the latest one and use its ID. Is there a way to join the ID's somehow?
I know that I can do a query like this to list all the commits the user via email.
SELECT
commits.id,
commits.cName,
users.email
FROM
commits
INNER JOIN userCommits ON commits.id = userCommits.commitID
INNER JOIN users ON userCommits.userID = users.id
WHERE users.email = "someonecool#hotmail.com"
But what I'm now trying to do is to insert into the database when the user creates a commit.
You perform the insert and select the inserted id as part of the same command for one table, then do the same for the other table
Once your app has knowledge of both ids, it can insert into the usercommits table
See Get the new record primary key ID from mysql insert query?
So I didn't mention I was using CodeIgniter. My bad. However the solutions provided would work. I just want to post what actually is used for other people that may encounter this.
As I learned for mySQL each client gets a session of it's own. This means that when you call $this->db->insert_id(), or SELECT LAST_INSERT_ID(); it will return YOUR last entered ID, not the server's last entered ID.
$commitData = array(
'cName' => $this->input->post('commitName'),
'cLocation' => $this->input->post('location'),
'cStartDate' => $this->input->post('startDate'),
'cEndDate' => $this->input->post('endDate')
);
$this->db->insert('commits', $commitData);
$userData = array(
'commitID' => $this->db->insert_id(),
'userID' => $user->id
);
$this->db->insert('userCommits', $userData);
There is obviously going to be security built around this but this is just the basic nuts and bolts.
Related
I have a drupal 7 installation in a shared hosting server and I am in a situation that the server provider removed some entries from node table when the database size crossed 1gb limit.
I lost a lot of entries, but some data exists in other tables with entity_id reference numbers.
I can query my data using the references from other tables but drupal interface could not show the data because of these missing entries.
So, how could I safely regenerate the entries into node table and its tables references ?
Where can I get the information about the usage of fields in drupal tables?
If possible, a step by step guide would be very helpful.
Jahangir is on the right track. The revision info will get you 90% of the way there.
My example makes the assumption that only the node table has been affected by these spurious deletions.
Start by getting any revisions that don't have a related node
$result = db_query('SELECT nid, MAX(vid) AS vid, uid, title, `timestamp`, `status`, `comment`, promote, sticky FROM {node_revision}
WHERE nid NOT IN (SELECT nid FROM {node}) GROUP BY nid');
You could do this next part using a node object, but given that we just need the node entries I would do it directly to the db:
foreach ($result as $record) {
//You might be able to get the created date by looking at the earliest revision
$min_result = db_query('SELECT nid, MIN(vid) as vid, `timestamp` FROM {node_revision} WHERE nid = :nid', array(':nid' => $record->nid));
$created = $min_result->fetchColumn(4);
$new_node = db_insert('node')
->fields(array(
'nid' => $record->nid,
'vid' => $record->vid,
'type' => 'YOU CANNOT GET THIS',
'language' => $record->language,
'title' => $record->title,
'uid' => $record->uid,
'created' => $created,
'updated' => $record->timestamp,
//you get the idea...
));
}
I wasn't able to find a way to retrieve the content type using the revisions, so that is the weakness of the solution. Assuming all of your field data is still in place, this should get your nodes back.
*disclaimer: I wasn't able to fake up an environment that resembled the problem presented here so this code is based on my experience and a little Googling. This hasn't been tested, but I hope it is still valuable. Downvotes humbly accepted.
I have a table in my MySQL database, compatibility_core_rules, which essentially stores pairs of ids which represent compatibility between parts which have fields with those corresponding ids. Now, my aim is to get all possible compatibility pairs by following the transitivity of the pairs (e.g. so if the table has (1,2) and (2,4), then add the pair (1,4)). So, mathematically speaking, I'm trying to find the transitive closure of the compatibility_core_rules table.
E.g. if compatibility_core_rules contains (1,2), (2,4) and (4,9), then initially we can see that (1,2) and (2,4) gives a new pair (1,4). I then iterate over the updated pairs and find that (4,9) with the newly added (1,4) gives me (1,9). At this point, iterating again would add no more pairs.
So my approach is to create a view with the initial pairs from compatibility_core_rules, like so:
CREATE VIEW compatibility_core_rules_closure
AS
SELECT part_type_field_values_id_a,
part_type_field_values_id_b,
custom_builder_id
FROM compatibility_core_rules;
Then, in order to iteratively discover all pairs, I need to keep replacing that view with an updated version of itself that has additional pairs each time. However, I found MySQL doesn't like me referencing the view in its own definition, so I make a temporary view (with or replace, since this will be inside a loop):
CREATE OR REPLACE VIEW compatibility_core_rules_closure_temp
AS
SELECT part_type_field_values_id_a,
part_type_field_values_id_b,
custom_builder_id
FROM compatibility_core_rules_closure;
No problems here. I then reference this temporary view in the following CREATE OR REPLACE VIEW statement to update the compatibility_core_rules_closure view with one iteration's worth of additional pairs:
CREATE OR REPLACE VIEW compatibility_core_rules_closure
AS
SELECT
CASE WHEN ccr1.part_type_field_values_id_a = ccr2.part_type_field_values_id_a THEN ccr1.part_type_field_values_id_b
WHEN ccr1.part_type_field_values_id_a = ccr2.part_type_field_values_id_b THEN ccr1.part_type_field_values_id_b
END ccrA,
CASE WHEN ccr1.part_type_field_values_id_a = ccr2.part_type_field_values_id_a THEN ccr2.part_type_field_values_id_b
WHEN ccr1.part_type_field_values_id_a = ccr2.part_type_field_values_id_b THEN ccr2.part_type_field_values_id_a
END ccrB,
ccr1.custom_builder_id custom_builder_id
FROM compatibility_core_rules_closure_temp ccr1
INNER JOIN compatibility_core_rules_closure_temp ccr2
ON (
ccr1.part_type_field_values_id_a = ccr2.part_type_field_values_id_a OR
ccr1.part_type_field_values_id_a = ccr2.part_type_field_values_id_b
)
GROUP BY ccrA,
ccrB
HAVING -- ccrA and ccrB are in fact not the same
ccrA != ccrB
-- ccrA and ccrB do not belong to the same part type
AND (
SELECT ptf.part_type_id
FROM part_type_field_values ptfv
INNER JOIN part_type_fields ptf
ON ptfv.part_type_field_id = ptf.id
WHERE ptfv.id = ccrA
LIMIT 1
) !=
(
SELECT ptf.part_type_id
FROM part_type_field_values ptfv
INNER JOIN part_type_fields ptf
ON ptfv.part_type_field_id = ptf.id
WHERE ptfv.id = ccrB
LIMIT 1
)
Now this is where things go wrong. I get the following error:
#1146 - Table 'db509574872.compatibility_core_rules_closure' doesn't exist
I'm very confused by this error message. I literally just created the view/table only two statements ago. I'm sure the SELECT query itself is correct since if I try it by itself and it runs fine. If I change the first line to use compatibility_core_rules_closure2 instead of compatibility_core_rules_closure then it runs fine (however, that's not much use since I need to be re-updating the same view again and again). I've looked into the SQL SECURITY clauses but have not had any success. Also been researching online but not getting anywhere.
Does anyone have any ideas what is happening and how to solve it?
MySQL doesn't support sub-queries in views.
You'll have to separate them... ie. using another view containing the sub-query inside you main view.
Running the create statement for that view will render an error, not creating it, hence the doesn't exist error you're getting when querying it.
This one is a pretty good one IMO and I have not seen a close exampled on SO or Google so here you go. I need to do the following within a Perl application I am building. Unfortunately it can not be done directly in MySQL and will require DBI. In a nutshell I need to take Database1.tableA and locate every record with the column 'status' matching 'started'. This I can do as it is fairly easy (not very good with DBI yet, but have read the docs), but where I am having issues is what I have to do next.
my $started_query = "SELECT primary_ip FROM queue WHERE status='started'";
my $started = $dbh->prepare($started_query);
$started->execute();
while ( my #started = $started->fetchrow_array() ) {
# Where I am hoping to have the following occur so it can go by row
# for only rows with the status 'started'
}
So for each record in the #started array, really only contains one value per iteration of the while loop, I need to see if it exists in the Database2.tableA and IF it does exist in the other database (Database2.tableA) I need to delete it from Database1.tableA, but if it DOES NOT exist in the other database (Database2.tableA) I need to update the record in the current database (Database1.tableA).
Basically replicating the below semi-valid MySQL syntax.
DELETE FROM tableA WHERE primary_ip IN (SELECT primary_ip FROM db2.tablea) OR UPDATE tableA SET status = 'error'
I am limited to DBI to connect to the two databases and the logic is escaping me currently. I could do the queries to both databases and store in #arrays and then do a comparison, but that seems redundant as I think it should be possible within the while ( my #started = $started->fetchrow_array() ) as that will save on runtime and resources required. I am also not familiar enough with passing variables between DBI instances and as the #started array will always contain the column value I need to query for and delete I would like to take full advantage of having that defined and passed to the DBI objects.
I am going to be working on this thing all night and already ran through a couple pots of coffee so your helping me understand this logic is greatly appreciated.
You'll be better off with fetchrow_hashref, which returns a hashref of key/value pairs, where the keys are the column names, rather than coding based on columns showing up at ordinal positions in the array.
You need an additional database handle to do the lookups and updates because you've got a live statement handle on the first one. Something like this:
my $dbh2 = DBI->connect(...same credentials...);
...
while(my $row = $started->fetchrow_hashref)
{
if(my $found = $dbh2->selectrow_hashref("SELECT * FROM db2.t2 WHERE primary_ip = ?",undef,$row->{primary_ip}))
{
$dbh2->do("DELETE FROM db1.t1 WHERE primary_ip = ?",undef,$found->{primary_ip});
}
else
{
$dbh2->do("UPDATE db1.t1 SET status = 'error' WHERE primary_ip = ?",undef,$found->{primary_ip}");
}
}
Technically, I don't "need" to fetch the row from db2.t2 into my $found since you're only apparently testing for existence, there are other ways, but using it here is a bit of insurance against doing something other than you intended, since it will be undef if we somehow get some bad logic going and that should keep us from making some potential wrong changes.
But approaching a relational database with loop iterations is rarely the best tactic.
This "could" be done directly in MySQL with just a couple of queries.
First, the updates, where t1.status = 'started' and t2.primary_ip has no matching value for t1.primary_ip:
UPDATE db1.t1 a LEFT JOIN db2.t2 b ON b.primary_ip = a.primary_ip
SET a.status = 'error'
WHERE b.primary_ip IS NULL AND a.status = 'started';
If you are thinking "but b.primary_ip is never null" ... well, it is null in a left join where there are no matching rows.
Then deleting the rows from t1 can also be accomplished with a join. Multi-table joins delete only the rows from the table aliases listed between DELETE and FROM. Again, we're calling "t1" by the alias "a" and t2 by the alias "b".
DELETE a
FROM db1.t1 a JOIN db2.t2 b ON a.primary_ip = b.primary_ip
WHERE a.status = 'started';
This removes every row from t1 ("a") where status = 'started' AND where a matching row exists in t2.
I have the following call in my RoR script:
Foo.where("event = 'Login'").group('user_id').order('user_id ASC').count()
This gives me a list of all users and how much they have logged in in the form of:
<userid1> => <count>, <userid2> => <count>, ...}
This is great and very close to what I wan but I've been unable to convince it to sort by the count of logins instead, what I'd really like to have it do. There is also a column that has some info about the login session in the form of a character delimited string. I'd like to get at certain parts of that information.
To achieve this I've tried using find_by_sql and when I make the following call:
Foo.find_by_sql("SELECT userid, COUNT(*) AS number, SUBSTRING_INDEX(stuff, ',', 1) AS info FROM <table> WHERE event = 'Login' GROUP BY userid")
What I get is a ilst of Foo entries that contain the userids but not the count or the info. When I run this in the MySQL workbench it works like a charm. Is there something else I need to do to get this to work? Also, would there be a way to just do this using Foo.select or Foo.where? Thanks.
Update I have also tried this format, as demonstrated here:
Foo.find(:all, :select => 'count(*) count, userid', :group =>'userid')
But this too merely responds with the userids and does not spit out the count.
Update 2 Looking at the output a bit more i can see now that when i do the find_by_fql call everything is being found in the correct way and even being sorted. It just isn't actually selecting the COUNT(*) or the SUBSTRING_INDEX.
Update 3 I also tried out this SO tip but when I tell it:
Foo.find(:all, :select => 'userid, count(*) as cnt', :group => 'userid')
It doesn't print or find anything related to the var cnt. I'm totally baffled here because I've seen more than one example now that does it this ^^ way and I've yet to get it to succeed.
Actually, your problem is not an SQL problem. To generate the correct SQL you would just need this:
Foo.where("event = 'Login'").group('user_id').order('count_all').count()
Take a look in your log and you'll find that this generates the following SQL:
SELECT COUNT(*) AS count_all, user_id AS school_id FROM `foos` GROUP BY user_id ORDER BY count_all
...and if you run that in your SQL console you'll get what you want.
The problem is that Rails doesn't return them in this order, Rails always returns these special group/count results in the order of the GROUP BY field. So, if you want them in a different order then you'll need to do it in Ruby after getting the hash back.
Code below returns an array of foos, checking any element inside foo will return userid/cnt
foos = Foo.find(:all, :select => 'userid, count(*) as cnt', :group => 'userid')
Is this what you're looking for?
foos.first.userid # will show userid
foos.first.cnt # will show count
I have a table Customers with a CustomerId field, and a table of Publications with a PublicationId field. Finally, I have a mapping table CustomersPublications that records which publications a customer can access - it has two fields: CustomerId field PublicationId.
For a given customer, I want to update the CustomersPublications table based on a list of publication ids. I want to remove records in CustomersPublications where the PublicationId is not in the list, and add new records where the PublicationId is in the list but not already in the table.
This would be easy in SQL, but I can't figure out how to do it in Linq.
For the delete part, I tried:
var recordsToDelete = dataContext.CustomersPublications.Where
(
cp => (cp.CustomerId == customerId)
&& ! publicationIds.Contains(cp.PublicationId)
);
dataContext.CustomersPublications.DeleteAllOnSubmit(recordsToDelete);
... but that didn't work. I got an error:
System.NotSupportedException: Method 'Boolean Contains(Int32)' has no supported translation to SQL
So, I tried using Any(), as follows:
var recordsToDelete = dataContext.CustomersPublications.Where
(
cp => (cp.CustomerId == customerId)
&& ! publicationIds.Any(p => p == cp.PublicationId)
);
... and this just gives me another error:
System.NotSupportedException: Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator
Any pointers?
[I have to say, I find Linq baffling (and frustrating) for all but the simplest queries. Better error messages would help!]
Wow. Almost by chance, I discovered that the reason I couldn't use Contains in my first example was that my publicationIds was an IList<int> rather than a an int[]. I changed it, and it worked.
Thanks, compiler message author! :-|