sqlduplicatesamazon-redshiftrownum
Remove duplicates based on two columns SQL
Hi everyone,
I need to remove duplicates based on two columns. ANON ID and USER ID. They have a many to many relationship. i.e. an anon id can have several user id's and vice versa. I need to leave just one instance. Anywhere anon id OR user id appears as a duplicate, this needs to be removed.
Sample data
Only rows 1, 4, 6, 7 should remain.
I know I can use rownum() and delete where rownum > 1 for ONE duplicate column. However in this case I need to remove any row where EITHER ANON id or USER ID has already appeared.
Any help would be appreciated.
Solution
You can have two rownum() functions and delete based on either results. If for some reason you can't have 2 rownum functions in one query, you can use dense_rank too.
- Math.Sin() gives incorrect value
- How to run my python script when the sunOS is start booting
- Express-session: not resetting cookie expiration on each request
- Getting a stack overflow exception when normalizing a vector
- Edit default summary function in R gives error for multiple variables
- What was a For loop? Why isn't it needed in R?
- How to use download button in shiny and save results in various formats (csv, texte, pdf, spss...)?
- Why are there two assignment operators, `<-` and `->` in R?
- lm()$assign: what is it?
- How to get the value of list(...) in R and S functions
- Design matrix for MLM from library(lme4) with fixed and random effects
- how to generate elements not included in my sample
- Create a matrix with gradually changing values without a for loop
- Emacs ESS and S-plus ( S+ ) 8.1 compatability
- How to lag date-index in a time-series in R?
- Nonlinear regression in R / S
- Calling R from S-Plus?