anupam1608 / Sql_engine

Python implementation of a mini SQL engine that runs a subset of SQL Queries using a command-line interface.

Mini-SQL-Engine

Python implementation of a mini SQL engine which runs a subset of SQL Queries using command line interface.

List of queries that can be executed:

1. Select all records from 1 or multiple tables

      Format: Select * from table_name

2. Aggragate functions (Sum, average, max, min)

      Format: Select max(col1) from table_name

3. Project columns

      Format: Select col1,col2 from table_name

4. Project with distinct from one table

      Format: Select distict(col1) from table_name

5. Select with "WHERE" condition( Relational operators "<, >, <=, >=, =" are handled )

      Format: Select * from table_name where <condition>

6. Select with multiple "WHERE" conditions joined by AND/OR operator

      Format: Select * from table_name where <condition-1> and/or <condition-2>

7. Sort based on order specified in "ORDER BY" clause

      Format: Select * from table_1 order by col1,col2

8. Join 2 tables with/without "WHERE" condition

      Format: Select * from table_1,table_2 [where <condition>]   

9. Select/Project Columns(could be any number of columns) from table using “​ group by​ ”:

      Format: Select col1, COUNT(col2) from table_name group by col1.

Data Format:

1. .csv file for tables. File name table1.csv, table name is "table1" 

2. metadata.txt file: having the structure for each table

    eg. <begin_table> 
	<table_name> 
	<attribute1> 
	.... 

	<attributeN> 
	<end_table>  

Sample input :

	python3 Sql_engine.py "SELECT * from table1 ORDER BY C;"