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If I have a list of movies that I am planning on storing inside of a database, and each movie has a list of strings (actors) for that movie. How do I store that?
You will have to create 3 table (for proper normalization)
1 table.> Movies (movieid,moviename)
2 table.> actors (actorid,actorname)
3 table.> movies_actor_relation (relationid, movieid,actorid)
column name ending with id are primary keys.
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I'm trying to develop a chat app and wanted to know what if there's any way to generate a unique ID between 2 different users.
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I'm making an app with a pretend stock market and I need to update a certain field (an array (prices) in an object (stock) of a document (the company). I need to have a random value between the last price - 2 and the last price + 2 and add that to the prices array for every company (document).
How would I go about this?
Thanks in advance!
Also any advice to simplify this question would be much appriciated!
Query the entire collection, iterate each document, and foreach document:
Read the contents of the array.
Update the contents of document with the new values you want it to have.
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I have a file with 120k records and the key is the username. I want to delete records for some username.
Delete all records for username in "ABC","dd","EEE" etc.
I am using R language
You could also use this.
df1[!(df1$username %in% c("ABC","dd","EEE")),]
df1[!(df1$username %in% c("ABC","dd","EEE")),]
Let me know if its still not working.
~Ashish
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Suppose I have data frame A. If A[I,j]=="z", I want to delete column j. How to do this?
Do you mean for a specific row, or all rows? If the former, use:
A <- A[grepl('^z$', unlist(A[i,]))]
Where i is the row where the character 'z' is potentially located. If the latter, could just use a for loop to do across all i.
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Say for e.g. I have 100 of tables in a database and I use SQL Server 2008 to generate the ERD diagram for me. How can I logically group the related tables so that at one glance user will only see the portion they want to see rather than the whole lot of tables in the database relationship?
You can create more than one diagram, showing the various areas of your database