Adds MySQL syntax to Transaction builder

[belchior]

Builder API

use sql_query_builder as sql;

let query = sql::Transaction::new()
  // one of methods
  .begin("")
  .start_transaction("")
  // optional methods
  .set_transaction("")
  // at least one of methods
  .alter_table(sql::AlterTable::new().alter_table("users"))
  .create_index(sql::CreateIndex::new().create_index("users_idx"))
  .create_table(sql::CreateTable::new().create_table("users"))
  .delete(sql::Delete::new().delete_from("users"))
  .drop_index(sql::DropIndex::new().drop_index("users_idx"))
  .drop_table(sql::DropTable::new().drop_table("users"))
  .insert(sql::Insert::new().insert_into("users"))
  .select(sql::Select::new().select("login"))
  .update(sql::Update::new().update("users"))
  // one of methods
  .rollback("")
  .commit("")
  .as_string();

let expected_query = "\
  BEGIN; \
  START TRANSACTION; \
  SET TRANSACTION; \
  ALTER TABLE users; \
  CREATE INDEX users_idx; \
  CREATE TABLE users; \
  DELETE FROM users; \
  DROP INDEX users_idx; \
  DROP TABLE users; \
  INSERT INTO users; \
  SELECT login; \
  UPDATE users; \
  ROLLBACK; \
  COMMIT;\
";

assert_eq!(expected_query, query);

Reference

• https://dev.mysql.com/doc/refman/8.4/en/commit.html
• https://dev.mysql.com/doc/refman/8.4/en/savepoint.html