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Merge pull request #142 from TidierOrg/case_whenfix
fix `case_when` syntax
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‎NEWS.md‎

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@@ -2,6 +2,7 @@
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## v.8.7 - 2025-07-07
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- AWS Athena backend bug fixes
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- add `temp` option to `@create_table`, default is `true`
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- adjust `case_when` syntax to match TidierData
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## v.8.6 - 2025-05-05
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- add `@pivot_longer`

‎README.md‎

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@@ -40,8 +40,8 @@ TidierDB.jl currently supports the following top-level macros:
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|----------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| **Data Manipulation** | `@arrange`, `@group_by`, `@filter`, `@select`, `@mutate` (supports `across`), `@summarize`/`@summarise` (supports `across`), `@distinct`, `@relocate`, `@transmute` |
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| **Joining/Setting** | `@left_join`, `@right_join`, `@inner_join`, `@anti_join`, `@full_join`, `@semi_join`, `@union`, `@union_all`, `@intersect`, `@setdiff` |
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| **Slice and Order** | `@slice_min`, `@slice_max`, `@slice_sample`, `@order`, `@window_order`, `@window_frame` |
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| **Utility** | `@show_query`, `@collect`, `@head`, `@count`, `@drop_missing`, `show_tables`, `@create_view` , `drop_view` |
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| **Slice and Order** | `@slice_min`, `@slice_max`, `@slice_sample`, `@arrange`, `@window_order`, `@window_frame` |
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| **Utility** | `@show_query`, `@collect`, `@head`, `@count`, `@drop_missing`, `show_tables`, `@create_table`, `@create_view`, `drop_view` |
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| **Helper Functions** | `across`, `desc`, `if_else`, `case_when`, `n`, `starts_with`, `ends_with`, `contains`, `as_float`, `as_integer`, `as_string`, `is_missing`, `missing_if`, `replace_missing` |
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| **TidierStrings.jl Functions** | `str_detect`, `str_replace`, `str_replace_all`, `str_remove_all`, `str_remove` |
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| **TidierDates.jl Functions** | `year`, `month`, `day`, `hour`, `min`, `second`, `floor_date`, `difftime`, `mdy`, `ymd`, `dmy` |
@@ -80,8 +80,8 @@ mtcars = DB.dt(db, path_or_name);
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DB.@mutate(mpg_squared = mpg^2,
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mpg_rounded = round(mpg),
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mpg_efficiency = case_when(
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mpg >= cyl^2 , "efficient",
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mpg < 15.2 , "inefficient",
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mpg >= cyl^2 => "efficient",
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mpg < 15.2 => "inefficient",
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"moderate"))
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DB.@filter(mpg_efficiency in ("moderate", "efficient"))
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DB.@arrange(desc(mpg_rounded))

‎docs/examples/UserGuide/key_differences.jl‎

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@@ -50,15 +50,3 @@ end
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_by = groups)
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@collect
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end
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# ## Differences in `case_when()`
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# In TidierDB, after the clause is completed, the result for the new column should is separated by a comma `,`
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# in contrast to TidierData.jl, where the result for the new column is separated by a `=>` .
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@chain dfv begin
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@mutate(new_col = case_when(percent > .5, "Pass", # in TidierData, percent > .5 => "Pass",
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percent <= .5, "Try Again", # percent <= .5 => "Try Again"
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true, "middle"))
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@collect
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end

‎docs/src/index.md‎

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@@ -144,8 +144,8 @@ We can replace `DB.collect()` with `DB.@show_query` to reveal the underlying SQL
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DB.@mutate(mpg_squared = mpg^2,
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mpg_rounded = round(mpg),
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mpg_efficiency = case_when(
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mpg >= cyl^2 , "efficient",
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mpg < 15.2 , "inefficient",
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mpg >= cyl^2 => "efficient",
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mpg < 15.2 => "inefficient",
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"moderate"))
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DB.@filter(mpg_efficiency in ("moderate", "efficient"))
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DB.@arrange(desc(mpg_rounded))

‎src/db_parsing.jl‎

Lines changed: 44 additions & 41 deletions
Original file line numberDiff line numberDiff line change
@@ -238,58 +238,61 @@ end
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function parse_case_when(expr)
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MacroTools.postwalk(expr) do x
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# Ensure we're dealing with an Expr object
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if isa(x, Expr)
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# Check for a case_when expression
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if x.head == :call && x.args[1] == :case_when
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# Initialize components for building a SQL CASE expression
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sql_case_parts = ["CASE"]
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# Iterate through the arguments of the case_when call, skipping the function name
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for i in 2:2:length(x.args)-1
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# Ensure we're only adding valid expressions
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cond = x.args[i]
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result = x.args[i + 1]
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# Handle `missing` by converting it to `NULL`
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result_formatted = if result === :missing
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"NULL"
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elseif isa(result, String)
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"'$result'"
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else
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result
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end
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if isa(x, Expr) && x.head == :call && x.args[1] == :case_when
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sql_parts = ["CASE"]
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args = x.args[2:end]
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expanded = Any[]
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default = nothing
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i = 1
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while i ≤ length(args)
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arg = args[i]
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if isa(arg, Expr) && arg.head == :call && arg.args[1] == :(=>)
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push!(expanded, arg.args[2], arg.args[3])
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i += 1
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elseif isa(arg, Pair)
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push!(expanded, arg.first, arg.second)
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i += 1
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# Append the WHEN-THEN part to the SQL CASE expression
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push!(sql_case_parts, "WHEN $(cond) THEN $(result_formatted)")
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end
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# Handle the default case, the last argument
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default_result = x.args[end]
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default_result_formatted = if default_result === :missing
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"NULL"
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elseif isa(default_result, String)
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"'$default_result'"
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else
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default_result
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if i == length(args)
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default = arg
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i += 1
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else
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push!(expanded, arg, args[i + 1])
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i += 2
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end
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end
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end
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# Append the ELSE part and the END
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push!(sql_case_parts, "ELSE $(default_result_formatted) END")
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# Combine into a complete SQL CASE statement
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sql_case = join(sql_case_parts, " ")
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# Directly return the SQL CASE statement string
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return sql_case
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for j in 1:2:length(expanded)
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cond = expanded[j]
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result = expanded[j + 1]
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res_sql = result === :missing ? "NULL" :
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isa(result, String) ? "'$result'" : result
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push!(sql_parts, "WHEN $(cond) THEN $(res_sql)")
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end
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if default !== nothing
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def_sql = default === :missing ? "NULL" :
283+
isa(default, String) ? "'$default'" : default
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push!(sql_parts, "ELSE $(def_sql)")
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end
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287+
push!(sql_parts, "END")
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return join(sql_parts, " ")
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end
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# Return the unmodified object if it's not an Expr or not a case_when call
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return x
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end
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end
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#this fxn is not being tested, bc its only in backends. - i might be able to get rid of it entirely as well
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# COV_EXCL_START
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function parse_char_matching(expr)

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