mysql query to find data entry not present in table for particular date
I wish to find particular fridays date whose entru is not present in the table
You can query the things that exist in the data. So to find missing dates, you can create a table with all dates in your desired date range and make a query which selects those dates that do not exists in your other table.
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I've a list of records (in excel) which I want to lookup in SQL table to find their entry date in table.
For example I've name of 200 customers in an excel sheet which are also in my SQL table but there are many others as well. I want to compare those users in table and find their date of joining the table i.e the date they were added to the table.
Do you have any column such as "customer_id"? If not, create it in the tables as it will make it easier for you to select and join tables. You can use the alter table statement to add the new column. After adding the columns, join the tables and use the select statement to find the required record.
You must have a key to bind those data. Any other way can be dangerous linking these informations. Maybe, the way is adapt your application or excel to provide this bind between the data.
Insert records based on date wise in table. like
'test1','test2','2017-12-10'
'test11','test22',2017-12-08'
'test12', 'test23', '2017-11-10'
latest date records will be on top. please suggest me how to do it.
I have a table with 5 million rows, and I want to get only rows that have the field date between two dates (date1 and date2). I tried to do
select column from table where date > date1 and date < date2
but the processing time is really big. Is there a smarter way to do this? Maybe access directly a row and make the query only after that row? My point is, is there a way to discard a large part of my table that does not match to the date period? Or I have to read row by row and compare the dates?
Usually you apply some kind of condition before retrieving the results. If you don't have anything to filter on you might want to use LIMIT and OFFSET:
SELECT * FROM table_name WHERE date BETWEEN ? AND ? LIMIT 1000 OFFSET 1000
Generally you will LIMIT to whatever amount of records you'd like to show on a particular page.
You can try/do a couple of things:
1.) If you don't already have one, index your date column
2.) Range partition your table on the date field
When you partition a table, the query optimizer can eliminate partitions that are not able to satisfy the query without actually processing any data.
For example, lets say you partitioned your table by the date field monthly and that you had 6 months of data in the table. If you query for a date between range of a week in OCT-2012, the query optimizer can throw out 5 of the 6 partitions and only scan the partition that has records in the month of OCT in 2012.
For more details, check the MySQL Partitioning page. It gives you all the necessary information and gives a more through example of what I described above in the "Partition Pruning" section.
Note, I would recommend creating/cloning your table in a new partitioned table and do the query in order to test the results and whether it satisfies your requirements. If you haven't already indexed the date column, that should be your first step, test, and if need be check out partitioning.
I'm wondering if it is possible to find all new rows in a table that were added in the last week if the table has no date column to signify when a given row was inserted into the table?
If so, can someone please advise me on how to accomplish this?
Or do I require a date column?
Thanks
You do need some kind of timestamp, Or keep external records somewhere, what was added last week ;-). Do you have some sort of auto-incrementing column id?
You do need a date col. 1 week means u are specifying time duration which requires dates or time field.
Otherwise you can keep a Status Column whose values are active or inactive. Each time row is displayed to user, you can update the status to inactive
You definitely need a date column. You could add one today, allowing all previous entries in the table to be null for that field, and have it start populating from now. After a week, your problem is solved.
Your best option is a timestamp, then you can select any particular period.
Alternatives would be an autoincrement field and you record the last number of the previous wee.
Or you have a status field that defaults to "NEW" and then you set it to "OLD" or whatever once you have processed it.
auto-incrementing id can be helpful.save a record id(last inserted record id).After a week compare id's with that specific record id will result you the newer rows as all the rows with larger id's will be of last week
I have a table (innodb) that will have billions of records eventually. Every 2nd week I expect ~ 500K records to get dropped into the table. I would want to partition this table based on the date on which the data is imported - luckily this is a field in the table that is of the format yyyy-mm-dd - Is it possible to partition it based on this date column ? I tried looking at the 18th chapter of mysql docs but couldn't figure out if this is possible.
You cannot partition on a date column directly, but you can partition on TO_DAYS(thedatecolumn). There's some examples here