# Join two dataframes with two common column headers

**URL:** <https://discourse.julialang.org/t/join-two-dataframes-with-two-common-column-headers/90993>\
**Category:** New to Julia\
**Created:** [November 29, 2022, 1:18pm UTC](https://discourse.julialang.org/t/join-two-dataframes-with-two-common-column-headers/90993 "2022-11-29T13:18:25Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Nash](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nash/32/14482_2.png) [@Nash](https://discourse.julialang.org/u/Nash)\
**Post date:** [November 29, 2022, 1:18pm UTC](https://discourse.julialang.org/t/join-two-dataframes-with-two-common-column-headers/90993/1 "2022-11-29T13:18:26Z")

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I have two data frames. The first, A, contains the headings “Timestamp”, “Ticker”, “Price”. The second, B, contains “Timestamp”, “Ticker”, “ProfitMargin”.

How do I join A and B, such that I get:

C = [Timestamp, Ticker, Price, ProfitMargin] for only those Timestamp values that are shared between A and B, and without having duplicate headers?

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<div class="post-metadata">

**Author:** ![p-gw](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/p-gw/32/210518_2.png) [@p-gw](https://discourse.julialang.org/u/p-gw)\
**Post date:** [November 29, 2022, 2:21pm UTC](https://discourse.julialang.org/t/join-two-dataframes-with-two-common-column-headers/90993/2 "2022-11-29T14:21:54Z")

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In the DataFrames.jl documentation are quite a few examples on how to join two data frames.

[https://dataframes.juliadata.org/stable/man/joins/](https://dataframes.juliadata.org/stable/man/joins/)

If I read your example right you want to `innerjoin` the two data frames `A` and `B`.

```julia-repl
julia> A = DataFrame(Timestamp = [1, 2, 3], Ticker = ["a", "b", "c"], Price = [1.0, 2.0, 3.0])
3×3 DataFrame
 Row │ Timestamp Ticker Price   
     │ Int64 String Float64 
─────┼────────────────────────────
   1 │ 1 a 1.0
   2 │ 2 b 2.0
   3 │ 3 c 3.0

julia> B = DataFrame(Timestamp = [2, 3, 4], Ticker = ["b", "c", "a"], ProfitMargin = [10.0, 20.0, 30.0])
3×3 DataFrame
 Row │ Timestamp Ticker ProfitMargin 
     │ Int64 String Float64      
─────┼─────────────────────────────────
   1 │ 2 b 10.0
   2 │ 3 c 20.0
   3 │ 4 a 30.0

julia> C = innerjoin(A, B, on = [:Timestamp, :Ticker])
2×4 DataFrame
 Row │ Timestamp Ticker Price ProfitMargin 
     │ Int64 String Float64 Float64      
─────┼──────────────────────────────────────────
   1 │ 2 b 2.0 10.0
   2 │ 3 c 3.0 20.0

```