SQL Syntax error when empty array is given into "In" method

Issue type: bug report

Database system/driver: mysql / mariadb

TypeORM version: 0.2.5

example code:

import { In } from 'typeorm'
// ...
const res = await Entity.find({ where: { id: In([]) } })
// ER_PARSE_ERROR: You have an error in your SQL syntax; ...

Generated SQL is similar to

SELECT * FROM users WHERE id IN();

In MySql IN () (empty IN) is a syntax error. To fix it i propose that either:

• improve type annotations not to allow empty arrays to be inserted inside In method with guard for checking array.length to be > 0 (this would be closest to mysql spec)
• In method converts empty array to FALSE so the result would be similar to

SELECT * FROM users WHERE id IN(FALSE); -- FALSE seems to work if used also in NOT IN(FALSE)

• remove IN() clause (may or may not create other sql syntax errors)

SELECT * FROM users WHERE id;

[Ginden]

There is workaround. You can do:

const res = await Entity.find({ where: { id: In([null, ...ids]) } })

X IN (NULL) is equivalent to 1=0, and X IN (NULL, 3) is equivalent to X IN (3)

[bogdan]

IMO the way typeorm treats In(null) is counter intuitive to people who are not 10 years in the SQL world. Ideally I would want ORM to understand what I mean like so:

find({where: {key: [null, 1, 2]}) // => where key is null or key in (1,2)
find({where: {key: [undefined]}) // => where key is null
find({where: {key: []) // => where 1 = 0