I have this chunk of SQL from a stored procedure and i can convert almost all of it, except for the 'INTO #t1' line which i believe is a temporary table:
SELECT siteid, MIN(Eload) + dbo.GetOffset(siteid, 'Eload', MIN(time)) AS Eload
INTO #t1
FROM calcdata WITH (NOLOCK)
WHERE siteid IN (SELECT siteid FROM community_site WHERE communityid = #communityid)
AND time between #start AND #finish
AND Eload < 1000000
AND Eload <> 0
GROUP BY siteid
What is the MySQL equivalent of the INTO #t1 line?
Thanks
You should use INSERT ... SELECT statement instead of SELECT with INTO.
I think that is
INTO "tablename"
MySQL does not allow to create temporary tables on the fly. You can create temporary table explicitly (see reference), but you are generally better off with simply creating normal table and dropping it after you are done with it. If you were to create it explicitly and fill, you need to know all fields in advance, which could be cumbersome.
Related
This question is in relation to the answer of [another question][1] that I've posted a year ago.
Basically, I need to translate the answer in PHP and I don't even know where to start. Should I use 6 queries? Should I concatenate every query into 1 query? Should I use mysqli_multi_query?
I just need some advice, tips, and I will do the rest, I will do the research needed on how to achieve this in PHP.
This is the query that works perfectly and that I need to translate in PHP:
-- Query 1
CREATE TEMPORARY TABLE t (
ID INT AUTO_INCREMENT PRIMARY KEY
)
SELECT
w.work_id,
w.name wname,
r.sort_name rsortname,
CONCAT(r.seo_url, '.', r.recording_id) as rurl
FROM
WORK AS w
JOIN recording AS r ON w.work_id = r.work_id
JOIN `release` AS rl ON r.release_id = rl.release_id
WHERE
r.is_performer = 1
AND r.is_video = 0
ORDER BY
w.work_id,
- rl.released_year DESC,
- rl.released_month DESC,
- rl.released_day DESC,
rl.release_id;
-- Query 2
CREATE TEMPORARY TABLE x
SELECT
MIN(ID) AS ID
FROM
t
GROUP BY
work_id;
-- Query 3
SELECT
work_id,
wname,
rurl
FROM
x
JOIN t ON x.ID = t.ID
ORDER BY
rsortname;
-- Query 4, 5
DROP TEMPORARY TABLE t;
DROP TEMPORARY TABLE x;
Should I use 6 queries?
Yes, and if these queries depend on variable from PHP then you should use prepared statements to execute them.
Should I concatenate every query into 1 query?
Definitely not. They are not one query, they are all separate and you should execute them separately.
Should I use mysqli_multi_query?
Never! Forget that this function even exists. It is difficult to use and completely unnecessary. Just use prepared statements or command-line interface in MySQL for administrative tasks.
I'm trying to sum columns x through x+n in an SQL table. Essentially, I have multiple tables that contain grades in them and a user_id. I want to sum all the grades to come up with a total grade column without specifying the column names as the names and number of columns changes with each table. For instance, one table might have columns (user_id, calculations, prelab, deductions) while another might have (user_id, accuracy, precision, graphs, prelab, deductions).
I could rename my columns col1, col2, col3, col4, col5, etc., but I can't figure out how to get around the varying number of columns.
As far as I know, there is no way to sum groups of columns without actually specifying the column names directly in SQL. It seems to me like this is a badly designed schema, but that's a separate topic.
In any your case, you're going to need to create a new column in each table that contains the sum of all the grades in that particular table, say called total, and then, do something like this:
select user_id, sum(table1.total, table2.total, table3.total)
from table1, table2, table3
where table1.user_id = table2.user_id
and table2.user_id = table3.user_id
group by user_id
1) You could write some pl/sql to go and hit the data dictionary and get the columns and then construct dynamic sql to do the work of adding them up correctly.
2) Or you could create views on top of the tables that contain the user_id and the sum of the interesting columns (the views themselves could be constructed programmatically - but that only needs to happen once rather than every time you want the totals).
But either of the above is probably over-kill compared to simply fixing your schema.
The following procedure would likely do the trick.
It will look for all column names for the given tableName in the INFORMATION_SCHEMA.COLUMNS table (excluding 'userid' - This may be subject to change if the name you use is different).
The procedure also creates a temporary table (this is also subject to improvement - it would probably be better to do a 'drop if exists before the create) to store the sum up to a point.
The items inside the loop is just building an SQL UPDATE statement with the given tableName argument and the columnName from the cursor and doing the math.
To test this (after creation):
call myProcedure('tableName');
DELIMITER //
DROP PROCEDURE IF EXISTS myProcedure //
CREATE PROCEDURE
myProcedure( tableName varchar(32) )
BEGIN
DECLARE done INT DEFAULT FALSE;
DECLARE columnName varchar(64);
DECLARE cur1 CURSOR FOR SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = tableName and COLUMN_NAME <> 'userid';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN cur1;
CREATE TEMPORARY TABLE intermediateresults(userid integer, sumOfScores integer);
SET #st1 = CONCAT('INSERT INTO intermediateresults (SELECT DISTINCT userid, 0 FROM ',tableName,' )' );
PREPARE stmt3 FROM #st1;
EXECUTE stmt3;
looping: LOOP
FETCH cur1 into columnName;
IF done THEN
LEAVE looping;
END IF;
SET #st1 = CONCAT('UPDATE intermediateresults set sumOfScores = sumOfScores + COALESCE( (SELECT ', columnName, ' FROM ',tableName, ' t WHERE t.userid=intermediateresults.userid) , 0)' );
PREPARE stmt3 FROM #st1;
EXECUTE stmt3;
DEALLOCATE PREPARE stmt3;
END LOOP;
CLOSE cur1;
SELECT * FROM intermediateresults;
DROP table intermediateresults;
END
//
DELIMITER ;
What might be of interest when doing this kind of thing:
INFORMATION_SCHEMA also has data on:
DATA_TYPE: which can be used to test if a specific column has the actual type you are expecting - a condition such as DATA_TYPE='int' can be added to the cursor definition to make sure that it is in fact an int (assuming that the columns to be summed are in fact INTs)
ORDINAL_POSITION: which can be used if you know in which order the columns are supposed to arrive (for cases where the last four are housekeeping, for instance)
TABLE_SCHEMA: the procedure above rather assumes that the table is only present in the current default schema. Using this would require an additional parameter in the procedure and a slight change in the constructed SQL statements.
I have created a procedure which returns a single column of officeid
call officetree(15);
I need to get list of employee under officeid's return by officetree procedure
select * from master_employee where officeid in ( here i want put my officeids return from procedure)
Is this possible to achieve this if yes what is the syntax for that.
Inside the procedure
Below ofcid is parameter of procedure
select `ofc_id`
from (select * from master_office
order by `ofc_parent_id`, `ofc_id`) master_office,
(select #pv := ofcid) office
where (find_in_set(`ofc_parent_id`, #pv) > 0
and #pv := concat(#pv, ',', `ofc_id`)) or ofc_id=ofcid
No, AFAIK, you can not use a SP as sub query in MySQL.
Ref: Using a stored procedure as subquery
Ref: https://forums.mysql.com/read.php?10,556522,556538#msg-556538
Is it possible to call stored procs in MySQL 5.5 subqueries.
No.
And for a suggestion, use stored procedure as few as possible (my ten-year experience tells me)
I think there is no way to use a stored procedure result like a subquery.
Your alternatives:
Use the statement from the procedure as subquery.
Fetch the IDs from the SP in PHP and execute a second query with the fetched IDs. select * from master_employee where officeid in ( list of previously fetched IDs )
Use a more powerfull design for the tree structure like "materialized path" or "transitive closure table"
I have a MySQL database with the following columns:
id company rating_score rating_place
I have companies and rating scores for each company. So, my db looks like:
id company rating_score rating_place
75 Intel 356.23
34 Sun 287.49
etc.
How can I assign the places (my rating_place column is empty) based on the score using php and mysql?
Thank you!
While Andrew G. Johnson is correct, you may not need to even store this information in the database.
The answer I have for you is simple: "Why do you want to store this in the database?"
If you have actually have a good reason, then you have a few choices based on how static the data is. If the data is created then inserted all at once, then ORDER BY rating_score DESC at the end of your statement should do it (if rating_place is assigned automatically from 1).
Otherwise, I would do something in a dedicated PHP page that, once your 2 columns are read, assigns the rating_place. If you manually enter data into your database, it shouldn't hurt to have to open the page. If data collection is automated, go ahead and throw a call to the "update_places_page" that updates the rating.
Edit:
Another option is just to create a view for rating_score that takes the top 20 and orders reorders them, then select from the new view and the actual table based on rating_score.
If you are just trying sort by highest rating to lowest add this to the end of your SQL query:
ORDER BY rating_score DESC
Or lowest to highest:
ORDER BY rating_score ASC
If you still want to do this your way [which I'd advise against] try this:
UPDATE mytable SET rating_place=(SELECT COUNT(*)+1 FROM mytable tablecheck WHERE tablecheck.rating_score > mytable.rating_score)
How about this:
update mytable set rating_place =(select count(*)+1 from mytable intb where intb.rating_score>mytable.rating_score)
----edit (after comment)
aww sorry, you can't select from the same table that you're updating in mysql, so try it with a temp table:
create table mytemptable as
select #row := #row +1 as place, mytable.id
from mytable, (SELECT #row := 0) r
order by rating_score desc;
and then just a similar update:
update mytable set rating_place = (
select place
from mytemptable
where mytemptable.id=mytable.id
)
after that you can drop that mytemptable.
although if you want to avoid a separate table and you can use php, you can try
$res=mysql_query("select id from mytable order by rating_score desc");
$ratings=array();
while ($r=mysql_fetch_assoc($res)) {
$ratings[]=$r['id'];
}
foreach ($ratings as $key=>$val) {
mysql_query("update mytable set rating_score=".($key+1)." where id=".$val);
}
Just sort by rating! This approach is just wrong as you would have to shift modify all data above a certain rank if you insert something. Bad data structure.
Well if you only insert something once or twice a year you could argue that integer sorting is faster, but well thats just a very minimal difference as sorting is based on Tree indexes and not on comparision.
So I have seen solutions like Andrew G. Johnson's. You could also tweak this further and only update entries with a higher score.
You could also create a trigger that does it automatically for you.
But let me explain why this is wrong:
Its redundant data. Its not atomic and consistent.
In a good atabase design you should always (if possible) store every information only at one point so it can be modified, deleted in an atomic way.
So you can avoid any inconsistencies and complications in the first place.
If you really wan't to "cache" the ranking, do it in your application.
So what are your alternatives to this if you really want to have database fields called like this?
Create a mysql view based on the sorted query.
You can also do caching there AFAIK if thats your goal.
But the better option for caching would be just to let the mysql query cache do the work for you. That would be the very best option.
I see no reason what so ever to do what you are trying to do, only valid arguments against it.
SELECT #row := 0;
UPDATE
`table`
SET
`table`.`rating_place` = (#row := #row +1)
ORDER BY
`table`.`rating_score` DESC;
PS: If you will be sending the queries from PHP, you will need to split the two, since PHP MySQL extension normally allows only single query per call.
yourQueryFunc('SELECT #row := 0;');
yourQueryFunc('
SELECT #row := 0;
UPDATE
`table`
SET
`table`.`rating_place` = (#row := #row +1)
ORDER BY
`table`.`rating_score` DESC;');
I would do a select using the order by desc clause and then update each row with the rating.
It is probably a lot more convenient to work out the place as you go. To do this you would read the values and order by Rating_Score (ASC). Then they would be in order of place as you read them out. If you like, you could then write this back into the table, but this would mean you have to constantly update the place value. If this database is going to be constantly changing from user input or something, I would recommend working out the places as you go. If the table will remain mostly static, you could have a place column.
What is the best way to get the auto-id value in the same SQL with a SELECT?
A forum said adding this "; has Return Scope_Identity()"
in the end of the SQL works in ASP.
Is there a corresponding way in PHP?
It depends on your database server. Using MySQL, call mysql_insert_id() immediately after your insert query. Using PostgreSQL, first query "select nextval(seq)" on the sequence and include the key in your insert query.
Querying for "select max(id) + 1 from tbl" could fail if another request inserts a record simultaneously.
In postgres the best way is to do something like:
insert into foos(name) values ('my_foo') returning id;
It depends on the database engine you are using. Some DBMS, like Firebird for example, have RETURNING clause you can add to your query. For example, if you have a table named TABLE1 with autoincrement column named ID, you can use this:
insert into TABLE1(columns...) values (values...) returning ID;
And it would return the inserted ID just like a regular select statement.
In Microsoft Transact SQL you can use ##IDENTITY.
e.g.
DECLARE #Table TABLE ( col0 INT IDENTITY, col1 VARCHAR(255), col2 VARCHAR(255))
INSERT INTO #Table (col1, col2) VALUES ('Hello','World!')
SELECT ##Identity
SELECT * FROM #Table
In php: mysql_insert_id()
http://us3.php.net/mysql_insert_id
or
If you wanted to genterate the number from your mySql select query, you could use this
EDIT:
SELECT LAST_INSERT_ID(`1`) + 1 FROM table
Be very careful: Apparently select nextval(seq) does not work in high concurrency - some other connection can insert between the time when you inserted and the time when you called select nextval(seq). Always test such code in high concurrency test harnesses.
In SQL Server a insert using the select statement can have an output clause which will return the identity value and whatever other columns you might need to identify which identity goes to which record. If you are using a values clause, then use select scope_identity () immediately after the insert.