Where OR goes
City is Oslo AND name is Ann OR Bob. Bob lives in Rome.
main.ts
import { Entity, PrimaryGeneratedColumn, Column, Brackets } from "typeorm";import { connect } from "./db"; @Entity()class Author { @PrimaryGeneratedColumn() id: number; @Column() name: string; @Column() city: string;} async function main() { const db = await connect([Author]); await db.query(`INSERT INTO "author" (name, city) VALUES ('Ann', 'Oslo'), ('Bob', 'Rome'), ('Cat', 'Oslo')`); const repo = db.getRepository(Author); const loose = await repo.createQueryBuilder("a") .where("a.city = :c", { c: "Oslo" }) .andWhere("a.name = :n1", { n1: "Ann" }) .orWhere("a.name = :n2", { n2: "Bob" }) .getMany(); console.log("no brackets: " + loose.map((a) => a.name).join(",")); const tight = await repo.createQueryBuilder("a") .where("a.city = :c", { c: "Oslo" }) .andWhere(new Brackets((w) => { w.where("a.name = :n1", { n1: "Ann" }).orWhere("a.name = :n2", { n2: "Bob" }); })) .getMany(); console.log("brackets: " + tight.map((a) => a.name).join(","));}main();db.ts 38 lines
import "reflect-metadata";import { DataSource } from "typeorm"; let show = false; /** One short line per statement: the verb and the table, enough to count what a call costs. */function short(sql: string): string { const s = sql.replace(/\s+/g, " ").trim(); if (/last_insert_rowid/i.test(s)) return "SELECT new id"; if (/^SELECT DISTINCT "distinctAlias"/i.test(s)) return "SELECT ids (paging)"; const verb = (s.match(/^(SELECT|INSERT INTO|UPDATE|DELETE FROM|BEGIN TRANSACTION|COMMIT|ROLLBACK)/i)?.[0] ?? s.split(" ")[0]).toUpperCase(); const table = s.match(/(?:FROM|INTO|UPDATE)\s+"(\w+)"/i)?.[1]; return table ? verb + " " + table + (/ JOIN /i.test(s) ? " JOIN" : "") : verb;} /** An in-memory SQLite database that prints one line for every SQL statement it runs. */export async function connect(entities: Function[]): Promise<DataSource> { const db = new DataSource({ type: "sqljs", entities, synchronize: true, logging: true, logger: { logQuery: (q: string) => { if (show) console.log("SQL " + short(q)); }, logQueryError: () => {}, logQuerySlow: () => {}, logSchemaBuild: () => {}, logMigration: () => {}, log: () => {}, }, }); await db.initialize(); show = true; return db;} 1. Predict the output
Tap the lines in the order you think they print.
- 1…
- 2…
- 3…
- 4…
- 5…