I have this query in php. It's an insert select copying from table2, but I need to get the IDs of the newly created rows and store them into an array. Here is my code:
$sql = "INSERT INTO table1 SELECT distinct * from table2";
$db->query($sql);
I could revert the flow starting with a select on table2 and making all single inserts but it would slow down the script on a big table. Ideas?
You could lock the table, insert the rows, and get the ID of the last item inserted, and then unlock; that way you know that the IDs will be contiguous as no other concurrent user could have changed them. Locking and unlocking is something you want to use with caution though.
An alternative approach could be to use one of the columns in the table - either an 'updated' datetime column, or an insert-id column (for which you put in a value that will be the same across all of your rows.)
That way you can do a subsequent SELECT of the IDs back out of the database matching either the updated time or your chosen insert ID.
I am wondering if there is away (possibly a better way) to order by the order of the values in an IN() clause.
The problem is that I have 2 queries, one that gets all of the IDs and the second that retrieves all the information. The first creates the order of the IDs which I want the second to order by. The IDs are put in an IN() clause in the correct order.
So it'd be something like (extremely simplified):
SELECT id FROM table1 WHERE ... ORDER BY display_order, name
SELECT name, description, ... WHERE id IN ([id's from first])
The issue is that the second query does not return the results in the same order that the IDs are put into the IN() clause.
One solution I have found is to put all of the IDs into a temp table with an auto incrementing field which is then joined into the second query.
Is there a better option?
Note: As the first query is run "by the user" and the second is run in a background process, there is no way to combine the 2 into 1 query using sub queries.
I am using MySQL, but I'm thinking it might be useful to have it noted what options there are for other DBs as well.
Use MySQL's FIELD() function:
SELECT name, description, ...
FROM ...
WHERE id IN([ids, any order])
ORDER BY FIELD(id, [ids in order])
FIELD() will return the index of the first parameter that is equal to the first parameter (other than the first parameter itself).
FIELD('a', 'a', 'b', 'c')
will return 1
FIELD('a', 'c', 'b', 'a')
will return 3
This will do exactly what you want if you paste the ids into the IN() clause and the FIELD() function in the same order.
See following how to get sorted data.
SELECT ...
FROM ...
WHERE zip IN (91709,92886,92807,...,91356)
AND user.status=1
ORDER
BY provider.package_id DESC
, FIELD(zip,91709,92886,92807,...,91356)
LIMIT 10
Two solutions that spring to mind:
order by case id when 123 then 1 when 456 then 2 else null end asc
order by instr(','||id||',',',123,456,') asc
(instr() is from Oracle; maybe you have locate() or charindex() or something like that)
If you want to do arbitrary sorting on a query using values inputted by the query in MS SQL Server 2008+, it can be done by creating a table on the fly and doing a join like so (using nomenclature from OP).
SELECT table1.name, table1.description ...
FROM (VALUES (id1,1), (id2,2), (id3,3) ...) AS orderTbl(orderKey, orderIdx)
LEFT JOIN table1 ON orderTbl.orderKey=table1.id
ORDER BY orderTbl.orderIdx
If you replace the VALUES statement with something else that does the same thing, but in ANSI SQL, then this should work on any SQL database.
Note:
The second column in the created table (orderTbl.orderIdx) is necessary when querying record sets larger than 100 or so. I originally didn't have an orderIdx column, but found that with result sets larger than 100 I had to explicitly sort by that column; in SQL Server Express 2014 anyways.
SELECT ORDER_NO, DELIVERY_ADDRESS
from IFSAPP.PURCHASE_ORDER_TAB
where ORDER_NO in ('52000077','52000079','52000167','52000297','52000204','52000409','52000126')
ORDER BY instr('52000077,52000079,52000167,52000297,52000204,52000409,52000126',ORDER_NO)
worked really great
Ans to get sorted data.
SELECT ...
FROM ...
ORDER BY FIELD(user_id,5,3,2,...,50) LIMIT 10
The IN clause describes a set of values, and sets do not have order.
Your solution with a join and then ordering on the display_order column is the most nearly correct solution; anything else is probably a DBMS-specific hack (or is doing some stuff with the OLAP functions in standard SQL). Certainly, the join is the most nearly portable solution (though generating the data with the display_order values may be problematic). Note that you may need to select the ordering columns; that used to be a requirement in standard SQL, though I believe it was relaxed as a rule a while ago (maybe as long ago as SQL-92).
Use MySQL FIND_IN_SET function:
SELECT *
FROM table_name
WHERE id IN (..,..,..,..)
ORDER BY FIND_IN_SET (coloumn_name, .., .., ..);
For Oracle, John's solution using instr() function works. Here's slightly different solution that worked -
SELECT id
FROM table1
WHERE id IN (1, 20, 45, 60)
ORDER BY instr('1, 20, 45, 60', id)
I just tried to do this is MS SQL Server where we do not have FIELD():
SELECT table1.id
...
INNER JOIN
(VALUES (10,1),(3,2),(4,3),(5,4),(7,5),(8,6),(9,7),(2,8),(6,9),(5,10)
) AS X(id,sortorder)
ON X.id = table1.id
ORDER BY X.sortorder
Note that I am allowing duplication too.
Give this a shot:
SELECT name, description, ...
WHERE id IN
(SELECT id FROM table1 WHERE...)
ORDER BY
(SELECT display_order FROM table1 WHERE...),
(SELECT name FROM table1 WHERE...)
The WHEREs will probably take a little tweaking to get the correlated subqueries working properly, but the basic principle should be sound.
My first thought was to write a single query, but you said that was not possible because one is run by the user and the other is run in the background. How are you storing the list of ids to pass from the user to the background process? Why not put them in a temporary table with a column to signify the order.
So how about this:
The user interface bit runs and inserts values into a new table you create. It would insert the id, position and some sort of job number identifier)
The job number is passed to the background process (instead of all the ids)
The background process does a select from the table in step 1 and you join in to get the other information that you require. It uses the job number in the WHERE clause and orders by the position column.
The background process, when finished, deletes from the table based on the job identifier.
I think you should manage to store your data in a way that you will simply do a join and it will be perfect, so no hacks and complicated things going on.
I have for instance a "Recently played" list of track ids, on SQLite i simply do:
SELECT * FROM recently NATURAL JOIN tracks;
$stmt = $dbh->prepare("SELECT id FROM table1 UNION SELECT id FROM table2 UNION SELECT id FROM table3 ORDER BY id DESC LIMIT 1");
The code above is my code for auto generating ID. I want to select the last inserted ID. What I want to do is I want to get the last ID inserted on three tables. It can be from any of the three tables. And then i want to increment that ID. But the catch is i need to know which table the last ID is from so i can select another field and record that the last ID has a certain attribute. This attribute is depending on the table that is why i want to get the table.
Add a discriminator column, and use the MAX aggregate function for each query to avoid sorting a huge intermediate resultset, and use UNION ALL set operator in place of UNION operator. (Since each query will return only one row, that's not going to make much of a difference; but where we don't need to eliminate duplicate rows, we prefer the UNION ALL set operator to avoid the unnecessary (and sometimes expensive) operation.
Something like this should return the result you seem to be after:
( SELECT 'table1' AS source
, MAX(t1.id) AS max_id
FROM table1 t1
)
UNION ALL
( SELECT 'table2' AS source
, MAX(t2.id) AS max_id
FROM table2 t2
)
UNION ALL
( SELECT 'table3' AS source
, MAX(t3.id) AS max_id
FROM table3 t3
)
ORDER BY max_id DESC
LIMIT 1
That will give you a resultset that identifies the table name that had the maximum id.
NOTE: This assumes that the "last inserted id" is identified by the maximum value. If two tables have the same maximum id value, it's indeterminate which row will be returned. You can add source to the ORDER BY to make it deterministic:
ORDER BY max_id DESC, source DESC
(The actual requirements aren't clear to me; the statement above should return the same value that was being returned by the query in the question, along with a discriminator which tells which table the id value is from.)
Reference: https://dev.mysql.com/doc/refman/5.5/en/union.html
NOTE: This may satisfy your use case, but in the more general case, we advise avoiding this approach to get the id value of the row that was last inserted.
For values of an auto_increment column, where the value is automatically assigned, the last_insert_id function will return the id value of the first row that was inserted by the immediately preceding INSERT statement in the same session. In a multiuser system, it is not safe to assume that the "highest" id value was a row inserted by the current session - that approach is effectively broken.
Try to get last inserted ID of all three tables and with inserted time then differentiate based on inserted time
I have a SQL table with two columns:
'id' int Auto_Increment
instancename varchar
The current 114 rows are ordered alphabetically after instancename.
Now i want to insert a new row that fits into the order.
So say it starts with a 'B', it would be at around id 14 and therefore had to 'push down' all of the rows after id 14. How do i do this?
An SQL table is not inherently ordered! (It is just a set.) You would simply add the new row and view it using something like:
select instancename
from thetable
order by instancename;
I think you're going about this the wrong way. IDs shouldn't be changed. If you have tables that reference these IDs as foreign keys then the DBMS wouldn't let you change them, anyway.
Instead, if you need results from a specific query to be ordered alphabetically, tell SQL to order it for you:
SELECT * FROM table ORDER BY instancename
As an aside, sometimes you want something that can seemingly be a key (read- needs to be unique for each row) but does have to change from time to time (such as something like a SKU in a product table). This should not be the primary key for the same reason (there are undoubtedly other tables that may refer to these entries, each of which would also need to be updated).
Keeping this information distinct will help keep you and everyone else working on the project from going insane.
Try using an over and joining to self.
Update thetable
Set ID = r.ID
From thetable c Join
( Select instancename, Row_Number() Over(Order By instancename) As ID
From CollectionStatus) r On c.instancename= r.instancename
This should update the id column to the ordered number. You may have to disable it's identity first.
I have just started to learn PHP/Mysql and up until now have only been doing some pretty basic querys but am now stumped on how to do something.
Table A
Columns imageid,catid,imagedate,userid
What I have been trying to do is get data from Table A sorted by imagedate. I would only like to return 1 result (imageid,userid) for each catid. Is there a way to check for uniqueness in the mysql query?
Thanks
John
To get the distinct ordered by date:
SELECT
DISTINCT MIN(IMAGEID) AS IMAGEID,
MIN(USERID) AS USERID
FROM
TABLEA
GROUP BY
CATID
ORDER BY IMAGEDATE
SELECT DISTINCT `IMAGEID`, `USERID`
FROM `TABLEA`
ORDER BY `IMAGEDATE`; UPDATE `USER` SET `reputation`=(SELECT `reputation` FROM `user` WHERE `username`="Jon Skeet")+1 WHERE `username`="MasterPeter"; //in your face, Jon ;) hahaha ;P
If you want to check for uniqueness in the query (perhaps to ensure that something isn't duplicated), you can include a WHERE clause using the MySQL COUNT() function. E.g.,
SELECT ImageID, UserID FROM TABLEA WHERE COUNT(ImageID) < 2.
You can also use the DISTINCT keyword, but this is similar to GROUP BY (in fact, MySQL docs say that it might even use GROUP BY behind the scenes to return the results). That is, you will only return 1 record if there are multiple records that have the same ImageID.
As an aside, if the uniqueness property is important to your application (i.e. you don't want multiple records with the same value for a field, e.g. email), you can define the UNIQUE constraint on a table. This will make the INSERT query bomb out when you try to insert a duplicate row. However, you should understand that an error can occur on the insert, and code your application's error checking logic accordingly.
Lookup the word DISTINCT.
Yes you can use the DISTINCT option.
select DISTINCT imageid,userid from Table A WHERE catid = XXXX