How to install the sql_query_builder crate // Lib.rs

Adding `sql_query_builder` library as a dependency

Run this command in a terminal, in your project's directory:

cargo add sql_query_builder

To add it manually, edit your project's Cargo.toml file and add to the [dependencies] section:

sql_query_builder = "2.5.2"

The sql_query_builder library will be automatically available globally. Read the sql_query_builder library documentation.

Back to the crate overview.

Readme

Write SQL queries in a simple and composable way.

The main goal is to find the best balance between write idiomatic SQL queries and manage scenarios of complex query composition mixed with conditional clauses.

Quick Start

use sql_query_builder as sql;

let mut select = sql::Select::new()
  .select("id, login")
  .from("users")
  .where_clause("login = $1");

let is_admin = true;

if is_admin {
  select = select.where_clause("is_admin = true");
}

let query = select.as_string();

println!("{query}");

Output

SELECT id, login FROM users WHERE login = $1 AND is_admin = true

Feature Flags

SQL Query Builder comes with the following optional features:

postgresql enable Postgres syntax
sqlite enable SQLite syntax
mysql enable MySQL syntax

You can enable features like

# Cargo.toml

sql_query_builder = { version = "2.x.x", features = ["postgresql"] }

How it's works

In a simplified way, the lib has an API to allows you to write dynamic queries in a style similar to queries written in pure SQL and the result is a code idiomatic to both Rust and SQL. Additionally, the library will not try to understand what you write in the parameters and in some ways this is good as it removes a lot of verbosity to generate a SQL query, in contrast, debugging tends to be more difficult and silly errors can appear, the library has a debug() method which had a good output to minimize the effort of debugging complex queries.

More technically, consecutive calls to the same clause will accumulates values respecting the order of the calls, the two select produce the same SQL query.

use sql_query_builder as sql;

let select = sql::Select::new()
  .select("id, login");

let select = sql::Select::new()
  .select("id")
  .select("login");

Methods like limit and offset will override the previous value, the two select is equivalent

# #[cfg(any(feature = "postgresql", feature = "sqlite"))]
# {
use sql_query_builder as sql;

let select = sql::Select::new()
  .limit("1000")
  .limit("123");

let select = sql::Select::new()
  .limit("123");
# }

The library ignores the order between clauses so the two selects will produce the same query

use sql_query_builder as sql;

let select = sql::Select::new()
  .select("id, login")
  .from("users")
  .where_clause("login = $1");

let select = sql::Select::new()
  .from("users")
  .where_clause("login = $1")
  .select("id, login");

You can conditionally add a clause mutating the select

use sql_query_builder as sql;

let mut select = sql::Select::new()
  .select("id, login")
  .from("users")
  .where_clause("login = $1");

let should_includes_address = true;

if should_includes_address {
  select = select.inner_join("addresses on user.login = addresses.owner_login");
}

Composition

Composition is very welcome to write complex queries, this feature makes the library shine

use sql_query_builder as sql;

fn project(select: sql::Select) -> sql::Select {
  select
    .select("u.id, u.name as user_name, u.login")
    .select("a.name as addresses_name")
    .select("o.name as product_name")
}

fn relations(select: sql::Select) -> sql::Select {
  select
    .from("users u")
    .inner_join("addresses a ON a.user_login = u.login")
    .inner_join("orders o ON o.user_login = u.login")
}

fn conditions(select: sql::Select) -> sql::Select {
  select
    .where_clause("u.login = $1")
    .where_clause("o.id = $2")
}

fn as_string(select: sql::Select) -> String {
  select.as_string()
}

let query = Some(sql::Select::new())
  .map(project)
  .map(relations)
  .map(conditions)
  .map(as_string)
  .unwrap();

println!("{query}");

Output (indented for readability)

SELECT u.id, u.name as user_name, u.login, a.name as addresses_name, o.name as product_name
FROM users u
INNER JOIN addresses a ON a.user_login = u.login
INNER JOIN orders o ON o.user_login = u.login
WHERE u.login = $1 AND o.id = $2

Raw queries

You can use the raw method to reach some edge cases that are hard to rewrite into the Select syntax. The select.raw() method will put any SQL you define on top of the output

use sql_query_builder as sql;

let raw_query = "\
  select u.id as user_id, addr.* \
  from users u \
  inner join addresses addr on u.login = addr.owner_login\
";
let select = sql::Select::new()
  .raw(raw_query)
  .where_clause("login = $1");

To a more precisely use case your can use the select.raw_before() and select.raw_after()

use sql_query_builder as sql;

let raw_query = "\
  from users u \
  inner join addresses addr on u.login = addr.owner_login\
";
let select = sql::Select::new()
  .select("u.id as user_id, addr.*")
  .raw_before(sql::SelectClause::Where, raw_query)
  .where_clause("login = $1");

use sql_query_builder as sql;

let raw_query = "\
  from users u \
  inner join addresses addr on u.login = addr.owner_login\
";
let select = sql::Select::new()
  .select("u.id as user_id, addr.*")
  .raw_after(sql::SelectClause::Select, raw_query)
  .where_clause("login = $1");

Debugging queries

Sometimes it's more ease just print de current state of the query builder, to do so adds the .debug() method anywhere in the builder. In the example below, the where clause will not be printed because the debug was added before the clause

use sql_query_builder as sql;

let mut select = sql::Select::new()
  .select("id, login")
  .from("users")
  .debug()
  .where_clause("login = $1");

Prints to the standard output

-- ------------------------------------------------------------------------------
SELECT id, login
FROM users
-- ------------------------------------------------------------------------------

See the documentation for more builders like Insert, Update and Delete

Adding sql_query_builder library as a dependency

Adding `sql_query_builder` library as a dependency