import { DB } from "https://deno.land/x/sqlite@v3.8/mod.ts";
Creates a custom (scalar) SQL function that can be used in queries.
Examples
const log = (value: unknown) => {
console.log(value);
return value;
};
db.createFunction(log);
db.query("SELECT name, log(updated_at) FROM users");
If a function is pure (i.e. always returns the same result
given the same input), it can be marked as deterministic
to
enable additional optimizations.
const discount = (price: number, salePercent: number) => num * (1 - salePercent / 100);
db.createFunction(discount, { deterministic: true });
db.query("SELECT name, discount(price, :sale) FROM products", { sale: 15 });
The function name can be set explicitly.
db.createFunction(() => Math.random(), { name: "jsRandom" });
db.query("SELECT jsRandom()");
Functions can also take a variable number of arguments.
const sum = (...nums: number[]) => nums.reduce((sum, num) => sum + num, 0);
db.createFunction(sum, { deterministic: true });
db.query("SELECT sum(1, 2), sum(1,2,3,4)");
Type Parameters
optional
A extends Array<SqlFunctionArgument> = Array<SqlFunctionArgument>optional
R extends SqlFunctionResult = SqlFunctionResultParameters
optional
options: SqliteFunctionOptions