qail-core 0.9.9

AST-native query builder - type-safe expressions, zero SQL strings
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# qail-core

**The AST-native query builder** — No SQL strings, no ORM magic, just type-safe expressions.

[![Crates.io](https://img.shields.io/crates/v/qail-core.svg)](https://crates.io/crates/qail-core)
[![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)

## Why AST-Native?

| Approach | How it works | SQL Injection |
|----------|--------------|---------------|
| **Raw SQL** (sqlx) | String literals: `"SELECT * FROM users"` | ⚠️ Possible |
| **ORM** (diesel, sea-orm) | Macros generate SQL at compile time | ✅ Safe |
| **AST-Native** (qail) | Typed AST → Wire protocol bytes | ✅ **Impossible** |

QAIL builds queries as an Abstract Syntax Tree that compiles directly to database wire protocol. There's no SQL string generation step—SQL injection isn't just prevented, it's structurally impossible.

## Installation

```toml
[dependencies]
qail-core = "0.9"
```

## Quick Start

```rust
use qail_core::ast::{QailCmd, Operator};
use qail_core::ast::builders::*;

// Build a query as typed AST
let cmd = QailCmd::get("users")
    .columns([col("id"), col("name"), col("email")])
    .filter(eq("active", true))
    .order_by([("created_at", Desc)])
    .limit(10);

// Use with qail-pg driver
let rows = driver.fetch_all(&cmd).await?;
```

## Ergonomic Expression Builders

```rust
use qail_core::ast::builders::*;

// Aggregates with FILTER
count_filter(vec![eq("status", "active")]).alias("active_users")

// Time expressions  
now_minus("24 hours")  // NOW() - INTERVAL '24 hours'

// CASE WHEN
case_when(gt("score", 80), text("pass"))
    .otherwise(text("fail"))
    .alias("result")

// Type casting
cast(col("amount"), "float8")
```

## Features

- **Type-safe expressions** — Compile-time checked query building
- **Ergonomic builders** — `count()`, `sum()`, `case_when()`, `now_minus()`
- **Full SQL support** — CTEs, JOINs, DISTINCT ON, aggregates with FILTER
- **JSON operators** — `->`, `->>`, `@>`, `?`
- **Schema parser** — Parse DDL into structured AST

## Ecosystem

| Crate | Purpose |
|-------|---------|
| **qail-core** | AST builder, parser, expression helpers |
| [qail-pg](https://crates.io/crates/qail-pg) | PostgreSQL driver (AST → wire protocol) |
| [qail](https://crates.io/crates/qail) | CLI tool for migrations and schema ops |

## License

MIT