# Query.jl join error - DataValues.DataValue{String} vs String

**URL:** <https://discourse.julialang.org/t/query-jl-join-error-datavalues-datavalue-string-vs-string/8281>\
**Category:** New to Julia\
**Created:** [January 11, 2018, 2:21am UTC](https://discourse.julialang.org/t/query-jl-join-error-datavalues-datavalue-string-vs-string/8281 "2018-01-11T02:21:17Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![tk3369](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tk3369/32/2824_2.png) [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Post date:** [January 11, 2018, 2:21am UTC](https://discourse.julialang.org/t/query-jl-join-error-datavalues-datavalue-string-vs-string/8281/1 "2018-01-11T02:21:17Z")

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I got this error when using [Query.jl](http://www.david-anthoff.com/Query.jl/stable/querycommands.html#Joining-1) to join two tables, where one table was read from [CSV.jl](http://juliadata.github.io/CSV.jl/stable/) and the other from [ExcelReaders.jl](https://github.com/davidanthoff/ExcelReaders.jl).

I guess I could convert the columns somehow but wondering if there’s a better way to handle that… thanks in advance.

```julia
The keys in the join clause have different types, 
DataValues.DataValue{String} and String.

```

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<div class="post-metadata">

**Author:** ![tk3369](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tk3369/32/2824_2.png) [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Post date:** [January 11, 2018, 3:25am UTC](https://discourse.julialang.org/t/query-jl-join-error-datavalues-datavalue-string-vs-string/8281/2 "2018-01-11T03:25:58Z")

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I worked around by “promoting” the value to DataValue type in the join condition.

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<div class="post-metadata">

**Author:** ![davidanthoff](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/davidanthoff/32/223493_2.png) [@davidanthoff](https://discourse.julialang.org/u/davidanthoff)\
**Post date:** [January 11, 2018, 5:08am UTC](https://discourse.julialang.org/t/query-jl-join-error-datavalues-datavalue-string-vs-string/8281/3 "2018-01-11T05:08:41Z")

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Yeah, that is the best option right now. I’m enforcing that the values one joins on have to be of the same type right now. I might relax that at some point, but I need to think about it a bit more 🙂