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https://github.com/faizan-khan-iit/ra_console
Implementation of Relational Algebra functions
https://github.com/faizan-khan-iit/ra_console
calculator dbms programming-assignment project relation-algebra-calculator relational-algebra
Last synced: 20 days ago
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Implementation of Relational Algebra functions
- Host: GitHub
- URL: https://github.com/faizan-khan-iit/ra_console
- Owner: faizan-khan-iit
- Created: 2016-10-18T12:00:24.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2017-09-21T05:21:01.000Z (over 7 years ago)
- Last Synced: 2024-10-27T12:55:53.883Z (2 months ago)
- Topics: calculator, dbms, programming-assignment, project, relation-algebra-calculator, relational-algebra
- Language: C++
- Homepage: https://faizan-khan-iit.github.io/ra_console/
- Size: 380 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Implementation of Relational Algebra functions
--------
### Aim of the Project
To write a program in C++ to implement Relational Algebra functions present in DBMS.
--------
### Functions implemented
The program implements the following Relational Algebra functions:
1. SELECT
2. PROJECT
3. RENAME
4. UNION
5. SET DIFFERENCE
6. CARTESIAN PRODUCT
--------
### Project Details
The program assumes the following:
* The database folder is present in the same directory as the main project file
* The database folder has a *db_info.txt* file containing the details of the database
* The database folder has a *tables* subdirectory which contains all table files in space separated form in *.txt* format
* The tables have their schema in the top three lines:
+ First line has table name
+ Second line has column names
+ Third line has column data types
* The data in the files is valid:
+ There is no newline
+ All data has same number of columns (except) table name
+ The data types corresponding to the data are correct
* The data types allowed are:
+ *int*
+ *float*
+ *varchar*
* Comparison accross data types is not allowed
* Queries are delimited by a **;**
--------
### Syntax
The basic syntax of the queries is as follows:
Show tables in database as specified in *db_info.txt*:
```{}
SHOW_TABLES;
```
SELECT:
```{}
SEL{predicate}(table_name);
```
PROJECT:
```{}
PRO{column_name1:column_name2}(table_name);
```
RENAME:
```{}
REN{new_table_name|column_name1:column_name2}(table_name);
```
UNION:
```{}
UNI(table_name1, table_name2);
```
SET DIFFERENCE:
```{}
DIF(table_name1, table_name2);
```
CARTESIAN PRODUCT:
```{}
CRP(table_name1, table_name2);
```
EXIT:
```{}
EXIT;
```
#### The predicate syntax for **SEL**:
```{}
SEL{(a > b | c = d) & e ! f}(table_name);
```
The available operators are:
1. **+** : Add two *ints* or *floats*
2. **-** : Subtract two *ints* or *floats*
3. __*__ : Multiply two *ints* or *floats*
4. **/** : Divide two *ints* or *floats*
5. **=** : Compare two operands, `TRUE` if equal
6. **!** : Compare two operands, `TRUE` if unequal
7. **>** : Compare two operands, `TRUE` if former is greater than latter
8. **<** : Compare two operands, `TRUE` if former is lesser than latter
9. **&** : Logical ```AND```
10. **|** : Logical ```OR```
NOTES:
* Comparison between different data types is not allowed
* `varchar` (Strings) are enclosed in `'`
* `float` operands *must* have a `.`
* Invalid operands are not allowed
#### The predicate syntax for **PRO**:
```{}
PRO{a:b:c:d}(table_name);
```
NOTES:
* Column names must be separated by a `:`
* Column names must be present in table
* Column names are displayed in given order
#### The predicate syntax for **REN**:
```{}
REN{new_table_name|a:b:c:d}(table_name);
REN{new_table_name}(table_name);
```
NOTES:
* Table name and column names must be separated by a `|`
* Column names must be separated by a `:`
* Column names must be valid
* Column names are renamed in given order
* If no column names are provided, the colum names are retained
* Either all or none of the column names must be provided
--------
### Sample Queries
```
1. SEL{faculty.salary > 80000 & dept = 'CSE'}(faculty);
2. PRO{id:name:grade}(studuent);
3. UNI(PRO{name}(faculty), PRO{name}(student));
4. DIF(PRO{name}(faculty), PRO{name}(student));
5. CRP(student, course);
6. REN{stud|stud_id:name:cgpa}(student);
```
For more queries, see [Query file](https://github.com/faizan-khan-iit/ra_console/blob/master/Queries/queries.pdf)
--------
### Comments:
* Syntax errors are not allowed
* SELECT takes exactly one predicate
* RENAME **cannot rename to a table already present**
* Column and table names must be alphanumeric
* Invalid comparisons between data types are not allowed
* UNI and DIF operations must **have same column names and data types**. Order need not be same
* Nested queries are allowed
* CRP operation needs **different column names**
* PRO should have **unique column names**
* All whitespaces are ignored
--------