toure/sql_query_builder

Write SQL queries in a simple and composable way

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

You can enable features like

# Cargo.toml

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

How it's works

In simple terms this library will not try to understand what you are writing inside the arguments, this is good because it's removes a lot of complexity and verbosity to generate a SQL query, in contrast debugging tends to be more difficult and silly error can araise. The lib has the debug() method with a nice output to minimize the effort to debug a complex query.

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 are the same

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 shouldIncludesAddress = true;

if shouldIncludesAddress {
  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