## Why DuckDB
There are many database management systems (DBMS) out there. But there is no one-size-fits all database system. All take different trade-offs to better adjust to specific use cases. DuckDB is no different.

To start with, DuckDB is a relational (table-oriented) DBMS that supports the Structured Query Language (SQL).

## Simple
SQLite is the world's most widely deployed DBMS. Simplicity in installation, and embedded in-process operation are central to its success. DuckDB adopts these ideas of simplicity and embedded operation.

## Portable
Thanks to having no dependencies, DuckDB is extremely portable.

## Feature-Rich
DuckDB provides serious data management features.

## Fast
DuckDB is designed to support analytical query workloads, also known as [online analytical processing (OLAP)](https://en.wikipedia.org/wiki/Online_analytical_processing).

## Free
DuckDB's development started while the main developers were public servants in the Netherlands.

## Use PSDuckDB - ADO.NET Style

In our ever-evolving world of data manipulation, the ability to efficiently pivot datasets can reveal new insights and trends. This example leverages PowerShell to dynamically transform city population data from a CSV file, enabling a year-over-year comparison. Let's dive into the process of creating a pivot table using PowerShell and DuckDB.

First, we establish a connection to DuckDB and create a table from our CSV dataset. This forms the foundation for our pivot operation, setting the stage for extracting valuable insights from raw data.

```powershell
$dataset = "cities.csv"

$db = New-DuckDBConnection

$db.sql("CREATE TABLE Cities AS SELECT * FROM '$dataset';")

$db.sql(@"
PIVOT Cities
ON Year
USING sum(Population);
"@) | Format-Table

$db.CloseDB()
```

With the table in place, the next step is to execute a pivot operation. This script restructures the data, allowing for a concise year-over-year comparison of city populations, revealing trends that may not be apparent in the raw data.

```
Country Name 2000 2010 2020
------- ---- ---- ---- ----
US New York City 8015 8175 8772
US Seattle 564 608 738
NL Amsterdam 1005 1065 115
```

By seamlessly integrating DuckDB with PowerShell, we unlock powerful data transformation capabilities. This example demonstrates how simple scripts can convert raw data into actionable insights, essential for informed decision-making. Explore these techniques further to harness the full potential of your datasets.

See [pivot.ps1](examples-sql-method/07-pivot.ps1)

## Examples

Check out the `SQL Introduction` and details for `DuckDB` https://duckdb.org/docs/sql/introduction

Refer to the [Data Import](https://duckdb.org/docs/data/overview) section for more information.

### Basic
[basic.ps1](examples/01-basic.ps1)

```powershell
psduckdb -command "select 10+2"
```

```ps
(10 + 2)
--------
12
```

### Read CSV
[read-csv.p1](examples/02-read-csv.ps1)

```powershell
psduckdb -command "SELECT * FROM '$PSScriptRoot\..\data\csv\sample\sales1.csv';" | Format-Table
```

```powershell
Region Tag Units Price State Source
------ --- ----- ----- ----- ------
West Sales1 927 923.71 Texas csv
North Sales1 466 770.67 Tennessee csv
East Sales1 520 458.68 Florida csv
East Sales1 828 661.24 Maine csv
```

### Read from Repo
[read-csv-from-repo](examples/06-read-csv-from-repo.ps1)

```powershell
$path = 'https://raw.githubusercontent.com/dfinke/ImportExcel/master/Examples/PassThru/sales.csv'

$stmt = @"
SELECT Item, SUM(UnitSold) AS Total_Sold
FROM '$path'
Group By Item
Order By Item;
"@

psduckdb -command $stmt | Format-Table
```

```powershell
Total_Sold Item
---------- ----
272 Apple
416 Banana
234 Kale
165 Pear
137 Potato
```

### Pivot the Data
[pivot.ps1](examples/07-pivot.ps1)

```powershell
$dataset = "$psscriptroot/../data/otherData/cities.csv"

$stmt = @"
CREATE TABLE Cities AS SELECT * FROM '$dataset';

PIVOT Cities
ON Year
USING sum(Population);
"@

psduckdb -command $stmt | Format-Table
```

```powershell
Name Country 2000 2010 2020
---- ------- ---- ---- ----
Amsterdam NL 1005 1065 1158
New York City US 8015 8175 8772
Seattle US 564 608 738
```

### Import Parquet Files
[read-parquet](examples/08-read-parquet.ps1)

```powershell
psduckdb -command "SELECT * FROM '$PSScriptRoot\..\data\parquet\sales.parquet';" | Format-Table
```

```powershell
Price Region State Units
----- ------ ----- -----
923.71 West Texas 927
770.67 North Tennessee 466
458.68w East Florida 520
661.24 East Maine 828
53.58 West Virginia 465
235.67 North Missouri 436
992.47 South Kansas 214
640.72 North North Dakota 789
508.55 South Delaware 712
```

## CLI API
The PSDuckDB CLI (Command Line Interface) is simple cli interface.

```powershell
PS C:\> psduckdb
```

```ps
Welcome to PSDuckDB! 07/06/2024 13:03:42
Connected to a transient in-memory database

PSDuckDB:
```

### Examples

Select a string.
```powershell
PSDuckDB: select 'quack' as my_col

my_col
------
quack
```

Generate a series of numbers from 0 to 5.
```powershell
PSDuckDB: SELECT * FROM generate_series(5);

generate_series
---------------
0
1
2
3
4
5
```

Read a parquet file from a local path.

```powershell
PSDuckDB: select * from 'D:\yourpath\sales.parquet'

Units Region Price State
----- ------ ----- -----
927 West 923.71 Texas
466 North 770.67 Tennessee
520 East 458.68w Florida
828 East 661.24 Maine
465 West 53.58 Virginia
436 North 235.67 Missouri
214 South 992.47 Kansas
789 North 640.72 North Dakota
712 South 508.55 Delaware
```

## DuckDB.NET

PSDuckDB leverages the DuckDB.NET bindings, developed by Giorgi. You can explore this work on GitHub at https://github.com/Giorgi/DuckDB.NET.

## Development

Please also refer the the [Contribution Guide](CONTRIBUTING.md).