https://github.com/viraltux/sqldf.jl
SQL for Julia Tables |> DataFrame
https://github.com/viraltux/sqldf.jl
dataframes julia query sql sqlite tables
Last synced: about 2 months ago
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SQL for Julia Tables |> DataFrame
- Host: GitHub
- URL: https://github.com/viraltux/sqldf.jl
- Owner: viraltux
- License: mit
- Created: 2021-07-04T09:19:44.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2021-08-14T11:20:46.000Z (about 4 years ago)
- Last Synced: 2025-07-24T11:37:36.922Z (3 months ago)
- Topics: dataframes, julia, query, sql, sqlite, tables
- Language: Julia
- Homepage:
- Size: 25.4 KB
- Stars: 11
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# SQLdf
This package allows SQL queries on any Julia type implementing the Table.jl interface an in particular the DataFrame type from DataFrames.jl. All results from a query are returned in a DataFrame type.
Versions prior to 0.2.0 would use R/sqldf via RCall. Although this is still possible by executing setRDB("R") before using sqldf, the default SQL engine is SQLite from SQLite.jl. If the default RDB is changed to "R" it can be set to its default with setRDB("SQLite").
The use of setRDB("R") requires [R to be
installed](https://juliainterop.github.io/RCall.jl/stable/installation/) with sqldf within.
# Introduction
Simply treat DataFrame objects (or any type implementing Tables.jl) like SQL tables.
# Examples
```julia
using SQLdf
```
## Simple Queries on DataFrames
```julia
DF = DataFrame(a=1:14, b=14:-1:1, c = split("Julia is great",""))
@sqldf "select count(*) from DF"
1×1 DataFrame
Row │ count(*)
│ Int64
─────┼──────────
1 │ 14
sqldf("""
SELECT *
FROM DF
WHERE a <= 5
ORDER BY a
""")
5×3 DataFrame
Row │ a b c
│ Int64 Int64 String
─────┼──────────────────────
1 │ 1 14 J
2 │ 2 13 u
3 │ 3 12 l
4 │ 4 11 i
5 │ 5 10 a
```
## Join DataFrames Query
```julia
T = DataFrame((a=1:14, c=split("Julia is fast!","")))
sqldf("""
select *
from DF join T on DF.b = T.a
order by DF.a
""")
14×5 DataFrame
Row │ a b c a:1 c:1
│ Int64 Int64 String Int64 String
─────┼─────────────────────────────────────
1 │ 1 14 J 14 !
2 │ 2 13 u 13 t
3 │ 3 12 l 12 s
4 │ 4 11 i 11 a
5 │ 5 10 a 10 f
6 │ 6 9 9
7 │ 7 8 i 8 s
8 │ 8 7 s 7 i
9 │ 9 6 6
10 │ 10 5 g 5 a
11 │ 11 4 r 4 i
12 │ 12 3 e 3 l
13 │ 13 2 a 2 u
14 │ 14 1 t 1 J
```
## Join Query Types implementing Tables interface
```julia
using TimeSeries
dates = Date(2021, 1, 1):Day(1):Date(2021, 1, 14)
TA = TimeArray(dates, 1:14)
@sqldf "select * from TA join DF where TA.A = DF.a"
14×5 DataFrame
Row │ timestamp A a:1 b c
│ Date Int64 Int64 Int64 String
─────┼─────────────────────────────────────────
1 │ 2018-01-01 1 1 14 J
2 │ 2018-01-02 2 2 13 u
3 │ 2018-01-03 3 3 12 l
4 │ 2018-01-04 4 4 11 i
5 │ 2018-01-05 5 5 10 a
6 │ 2018-01-06 6 6 9
7 │ 2018-01-07 7 7 8 i
8 │ 2018-01-08 8 8 7 s
9 │ 2018-01-09 9 9 6
10 │ 2018-01-10 10 10 5 g
11 │ 2018-01-11 11 11 4 r
12 │ 2018-01-12 12 12 3 e
13 │ 2018-01-13 13 13 2 a
14 │ 2018-01-14 14 14 1 t
```