Below is the table i am trying to write a query for to add new rows for every user.
My question is how do i add a new row for every user? Which means for userId 2 I add AccId 4 and similarly for 7 and 8. Since there is no concept of for loop in sql, do i make use of while? If so, how to loop through the userIds since the IDs are not in equal increments?
something like this maybe:
Insert Into mytable (UserID, AccID)
Select UserID, max(accId)+1
From MyTable
Group By UserID
You can re-run it every time, you will create the next value.
Untested on a MySql server:
INSERT INTO MyTable ( ID, AccId )
SELECT MyValues.ID, MyValues.Espr1
FROM (SELECT MyTable.ID, Max([AccId]+1) AS Espr1
FROM MyTable
GROUP BY MyTable.ID) AS MyValues;
Basically we prefetch Id a AccId grouping the values of Id and grabbing the Max of AccId.
Then we add these rows to the main table. Repeating the query we will add the value 5 (AccId) and so on, always adding 1
Related
I have two tables, both with same data:
IP address | count
I need to combine the two tables into new one that contains data from both original tables.
IF there is a matching record in both tables, their count should be added.
IF there is a record that exists only in one table it gets copied over to the new table.
Let first table be called ip_data_january, second called ip_data_february and the one I am trying to create is ip_data_yearly. Thanks in advance.
1st insert only new ip addresses (with count starting at zero)
insert into ip_data_yearly (ip_adress, count)
(select distinct ip_address, '0' from jan_table
where ip_addess not in (select ip_adress from ip_data_yearly);
2nd update the count
update ip_data_yearly y
set count= count +
(select count(j.ip_adress) from jan_table where j.ip_adress=y.ip_adress);
..
3rd do this for all months
You can use ON DUPLICATE KEY UPDATE
I Assume Unique index on IP_Address .. then
INSERT INTO ip_data_yearly (ip_adress)
SELECT IP_Address FROM IP_Data_January
UNION ALL SELECT IP_Address FROM IP_Data_February
ON DUPLICATE KEY UPDATE `count`=`count`+1;
If the IP_Data_Yearly table is empty, an INSERT with a subquery that aggregates count by IP should do the trick:
INSERT INTO IP_Data_Yearly
SELECT IP_Address, SUM(Count)
FROM (
SELECT IP_Address, Count FROM IP_Data_January
UNION ALL SELECT IP_Address, Count FROM IP_Data_February
) IPCombined
GROUP BY IP_Address
I'm pretty stuck on a Mysql query.
I have a table with three columns;
user_id | person_id | score.
The table is going to be used to store top 5 highscores for each person.
I need at query that checks if there is less than five rows for a specific person.
Is there is less, insert new row. But if there is five rows I have to replace the lowest score with the new one.
It is for a webservice written in PHP and the data about the new score is posted to the method as params.
Been stuck for some hours now — is it even possible to make this happen in one query ?
You can use stored procedure in mysql. I dont know the names of the tables but if you look closer you will understand how it works.
DELIMITER $$
DROP PROCEDURE IF EXISTS test $$
CREATE PROCEDURE test( IN testparam VARCHAR(22) )
BEGIN
DECLARE count INT(11);
SET count = (SELECT COUNT(*) FROM persons );
IF count < 5 THEN
insert into table_needed_for_insert values(testparam);
ELSE
update table_needed_for_insert where score=(select min(score) from table_needed_for_insert);
END IF;
select * from table_needed_for_insert
END $$
DELIMITER;
And how to execute this thing CALL test(1); 1 is the parameter, you can create as many as you need.
And from php you can call directly as like
$result = mysql_query("call test(".$param.")");
And here you can check a tutorial on mysql stored procedures:
http://www.mysqltutorial.org/mysql-stored-procedure-tutorial.aspx
It might be possible if you have a unique key which identifies the lowest score. Then you could use the
INSERT ... ON DUPLICATE KEY construct. But you would have to install a trigger which keeps explicit track of the lowest score.
I would propose this scenario (I have not tried it, it is just an idea):
as I understand, you only need 5 ids. you can run a subqueries like these
SELECT MAX(id) AS last_id FROM table
SELECT MIN(score), id AS lowest_id FROM table
then
insert or replace into table (id, ...) values ( MIN(last_id+1, lowest_id), ... )
there are possible mistakes and also only one subquery is possible, but I hope you get the main idea
The simplest way imo is to insert data,
INSERT INTO top_scores (user_id, person_id, score_id) VALUES (1,2,3)
then delete inappropriate rows
DELETE top_scores FROM top_scores
INNER JOIN
(SELECT * FROM top_scores WHERE person_id = 2 ORDER BY score ASC LIMIT 5, 1000000) AS inappropriate_rows
USING (user_id, person_id, score)
First we start with empty table
rows = 0
Second we insert random rows let say 3400
rows = 3400
For the third time i count how many rows are in the table, then insert the new rows and after that delete rows <= from the count.
This logic only work for the first time. If that repeat the count will always be 3400 but the id will increase so it will not delete the rows
I cant use last inserted ID since the rows are random and I dont how many it will load.
// Update
"SELECT count(*) from table" - the total count so far
"INSERT INTO tab_videos_watched (id , name) values (id , name)" - this is random can be 3400 or 5060 or 1200
"DELETE FROM table WHERE idtable <= $table_count"
If id is auto incremented, then you should use like:
select max(id) from my_table;
Read this maxId into a variable and then use when issued a delete query like:
delete from my_table where id <= ?;
Replace query parameter with the last found maxId value.
Alternatively you can define a column last_inserted as datetime type.
Before next insertions, select it into a local variable.
select max(last_inserted) as 'last_inserted' from my_table;
And after insertions are made, use the last_inserted to delete records.
delete from my_table where last_inserted <= ?;
Replace query parameter with the last found last_inserted value.
How can I store only 10 rows in a MySQL table? The older rows should be deleted when a new row is added but only once the table has 10 rows.
Please help me
You could achieve this with an after insert trigger, delete the row where it is min date. e.g. DELETE FROM myTable WHERE myTimestamp = (SELECT MIN(myTimestamp) FROM myTable) but that could in theory delete multiple rows, depending on the granularity of your updates.
You could have an incrementing sequence, and always just delete the min of that sequence.
The question is why you'd want to do this though? It's a slightly unusual requirement.
A basic example (not validated/executed, I don't have mySQL on this particular machine) would look something like.
CREATE TRIGGER CycleOldPasswords AFTER INSERT ON UserPasswords FOR EACH ROW
set #mycount = SELECT COUNT(*) FROM UserPasswords up where up.UserId = NEW.UserId;
if myCount >= 10 THEN
DELETE FROM UserPasswords up where up.Timestamp = (SELECT min(upa Timestamp) FROM UserPasswords upa WHERE NEW.UserId = upa.UserId) AND NEW.UserId = up.UserId;
END
END;
You can retrieve the last inserted id when your first row is inserted, and store it in a variable. When 10 rows are inserted, delete the row having id < id of the first inserted record. Please try it.
first of all insert all values using your insert query
and then run this query
delete from table_name where (cond) order by id desc limit 10
must specify an id or time in one column
Two questions:
1)
There are several tables that are used as an archive for other tables.
To do so, there is a
INSERT INTO data_archive_table (SELECT * FROM data_table)
The problem is that the data_table.id should be kept as data_archive_table.old_id.
Is there a way to write a query that will look like: SELECT *, id AS old_id FROM data_table, while the results columns will have ONLY the old_data column, and NOT the original id column?
Using all column names is the only option I see, but I prefer to avoid it.
2)
I want to add a virtual column named deleted_time to the insertion query, that will hold the current time.
Can it be done? if so - how ?(tutorials will be great)
Try this:
1.) You can use something like this query:
INSERT INTO data_archive_table
SELECT id AS old_id -- be sure that data_archive_table has column oldID
,... -- You need to specify the names of the columns
FROM data_table
WHERE id = 'IDHERE' -- If you want to have condition.
2.) For this, you can add the value directly in you select statement
INSERT INTO `tableName`
SELECT colA,
colB,
, ...
, NOW() as deleted_time -- NOW() is a function in MySQL
FROM `sourceTable`
WHERE colA = 'IDHERE' -- If you want to have condition.
NOW() in MySQL