By default, make query column names unique

src/SQLite.jl

@@ -458,7 +458,7 @@ end
 execute(stmt::Stmt, params::DBInterface.StatementParams) =
     execute(stmt.db, _stmt(stmt), params)
 
-execute(stmt::Stmt; kwargs...) = execute(stmt, kwargs.data)
+execute(stmt::Stmt; kwargs...) = execute(stmt, values(kwargs))
 
 function execute(db::DB, sql::AbstractString, params::DBInterface.StatementParams)
      # prepare without registering _Stmt in DB
@@ -470,7 +470,7 @@ function execute(db::DB, sql::AbstractString, params::DBInterface.StatementParam
     end
 end
 
-execute(db::DB, sql::AbstractString; kwargs...) = execute(db, sql, kwargs.data)
+execute(db::DB, sql::AbstractString; kwargs...) = execute(db, sql, values(kwargs))
 
 """
     SQLite.esc_id(x::Union{AbstractString,Vector{AbstractString}})

src/tables.jl

@@ -109,14 +109,24 @@ Calling `SQLite.reset!(result)` will re-execute the query and reset the iterator
 The resultset iterator supports the [Tables.jl](https://github.com/JuliaData/Tables.jl) interface, so results can be collected in any Tables.jl-compatible sink,
 like `DataFrame(results)`, `CSV.write("results.csv", results)`, etc.
 """
-function DBInterface.execute(stmt::Stmt, params::DBInterface.StatementParams)
+function DBInterface.execute(stmt::Stmt, params::DBInterface.StatementParams; allowduplicates::Bool=false)
     status = execute(stmt, params)
     _st = _stmt(stmt)
     cols = sqlite3_column_count(_st.handle)
     header = Vector{Symbol}(undef, cols)
     types = Vector{Type}(undef, cols)
     for i = 1:cols
-        header[i] = sym(sqlite3_column_name(_st.handle, i))
+        nm = sym(sqlite3_column_name(_st.handle, i))
+        if !allowduplicates && nm in view(header, 1:(i - 1))
+            j = 1
+            newnm = Symbol(nm, :_, j)
+            while newnm in view(header, 1:(i - 1))
+                j += 1
+                newnm = Symbol(nm, :_, j)
+            end
+            nm = newnm
+        end
+        header[i] = nm
         types[i] = Union{juliatype(_st.handle, i), Missing}
     end
     return Query(stmt, Ref(status), header, types, Dict(x=>i for (i, x) in enumerate(header)))

test/runtests.jl

@@ -424,6 +424,11 @@ tbl3 = (c = [7, 8, 9], a = [4, 5, 6])
 # Test busy_timeout
 @test SQLite.busy_timeout(db, 300) == 0
 
+# 253, ensure query column names are unique by default
+db = SQLite.DB()
+res = DBInterface.execute(db, "select 1 as x2, 2 as x2, 3 as x2, 4 as x2_2") |> columntable
+@test res == (x2 = [1], x2_1 = [2], x2_2 = [3], x2_2_1 = [4])
+
 @testset "load!()/drop!() table name escaping" begin
     tbl = (a = [1, 2, 3], b = ["a", "b", "c"])
     SQLite.load!(tbl, db, "escape 10.0%")