GoSQL

A basic SQL query engine in Go

• It can parse and execute simple SQL queries on CSV files
• Supports SELECT, FROM, WHERE, and LIMIT clauses.

Architecture

The program is simple:

graph LR
    A[Parse Query] --> B[Create AST]
    B --> C[Execute Query against CSV]
    C --> D[Output Results]

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An AST is an Abstract Syntax Tree. It is a tree representation of the structure of the SQL query, eg

{
    "type": "SELECT",
    "value": ["first_name", "last_name"]
},
{
    "type": "FROM",
    "value": "data/addresses"
},
{
    "type": "WHERE",
    "left": "first_name",
    "operator": "=",
    "right": "John"
}

Installation

1. Ensure you have Go installed on your system.
2. Clone this repository:

   git clone https://github.com/archiewood/gosql.git
   cd gosql

3. Build the project:

   go build

Usage

Run the program with your SQL query as an argument:

./gosql "SELECT column1, column2 FROM table WHERE column3 = 'value' LIMIT 10"

The program expects CSV files to be relative to the directory from which you run the program, named as <table>.csv. You can use unix paths eg

./gosql "SELECT * FROM data/wait_times"

Flags

• -ast: Print the Abstract Syntax Tree of the query

Example:

./gosql -ast "SELECT * FROM users WHERE country = 'USA' LIMIT 5"

Friendly Syntax

• SELECT not required, * assumed if not specified
• Trailing commas after final select clause are allowed