docs/source/user-guide/example-usage.md

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# Example Usage

## Update `Cargo.toml`

Add the following to your `Cargo.toml` file:

```toml
datafusion = "8.0.0"
tokio = "1.0"
```

## Run a SQL query against data stored in a CSV:

```rust
use datafusion::prelude::*;

#[tokio::main]
async fn main() -> datafusion::error::Result<()> {
  // register the table
  let ctx = SessionContext::new();
  ctx.register_csv("example", "tests/example.csv", CsvReadOptions::new()).await?;

  // create a plan to run a SQL query
  let df = ctx.sql("SELECT a, MIN(b) FROM example GROUP BY a LIMIT 100").await?;

  // execute and print results
  df.show().await?;
  Ok(())
}
```

## Use the DataFrame API to process data stored in a CSV:

```rust
use datafusion::prelude::*;

#[tokio::main]
async fn main() -> datafusion::error::Result<()> {
  // create the dataframe
  let ctx = SessionContext::new();
  let df = ctx.read_csv("tests/example.csv", CsvReadOptions::new()).await?;

  let df = df.filter(col("a").lt_eq(col("b")))?
           .aggregate(vec![col("a")], vec![min(col("b"))])?;

  // execute and print results
  df.show_limit(100).await?;
  Ok(())
}
```

## Output from both examples

```text
+---+--------+
| a | MIN(b) |
+---+--------+
| 1 | 2      |
+---+--------+
```