pyDB - Python DB Emulator

A sql lite-esque engine coded from scratch in pure python3 without any data crunching libraries like pandas / scipy. Created as a part of my graduate database project at New York University. Recieved 95/100 points and an A grade.

Required External Packages :

1. Btrees : https://pypi.org/project/BTrees/ (used for btree indexing in tables)
2. Numpy : https://numpy.org

Steps to run :

1. Clone the repository.
2. Install and update required python3 packages.
3. cd repo_directory
4. python3 driver.py

Format of commands :

All the sample commands to be run are found in commands.txt. The commands follow the following syntax. More commands can be added to commands.txtif required. For a complete list of commands, constraints and requirements please see this file.

R := inputfromfile(sales1) : Used to import a vertical bar delimited file. Here R is the result table. Please ensure you use the :=to prevent syntax errors. The first line contains the column names. The subsequent lines contain one recored each. Please view example files one and two for sample data and formatting. Another example is S := inputfromfile(sales2).

R1 := select(R, (time > 50) or (qty < 30)) Equivalent to Select * from R where time > 50 or qty < 30.

R2 := project(R1, saleid, qty, pricerange) Equivalent to Select saleid, qty, pricerange from R1.

R3 := avg(R1, qty) Eqivalent to Select avg(qty) from R1.

R4 := sumgroup(R1, time, qty) Equivalent to Select sum(time), qty from R1 group by qty.

R5 := sumgroup(R1, qty, time, pricerange) Equivalent to Select sum(qty), time, pricerange from R1 group by time, pricerange.

R6 := avggroup(R1, qty, pricerange) Equivalent to Select avg(qty), pricerange from R1 group by by pricerange.

T := join(R, S, R.customerid = S.C) Equivalent to Select * from R, S where R.customerid = S.C.

T1 := join(R1, S, (R1.qty > S.Q) and (R1.saleid = S.saleid)) Equivalent to Select * from R1 join S where R1.qty > S.Q and R1.saleid = S.Saleid

T2 := sort(T1, S_C) Equivalent to Select * from T1 order by S_C.

T2prime := sort(T1, R1_time, S_C) Equivalent to Select * from T1 order by R1_time,S_C (in that order)

T3 := movavg(T2prime, R1_qty, 3) Performs the three item moving average of T2prime on column R_qty. This will be as long as R_qty. Eg : three way moving average of 4 8 9 7 will be 4 6 7 8

T4 := movsum(T2prime, R1_qty, 5) Performs the five item moving sum of T2prime on column R_qty

Btree(R, qty) or Hash(R, qty) Creates an index on R based on column qty. Equality selections and joins on R will use the index if available. Index uses Btree / Hash Table depending on command.

For a complete list of commands, constraints and requirements please see this file.