From 0502a0b8bb2d573c7e06be693f4366a927d3d5cb Mon Sep 17 00:00:00 2001
From: Jakub Knejzlik <jakub.knejzlik@gmail.com>
Date: Wed, 31 Jan 2024 20:00:05 +0100
Subject: [PATCH] Add math functions

---
 src/Function.test.ts |  8 ++++++++
 src/Function.ts      | 20 ++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/Function.test.ts b/src/Function.test.ts
index a8e6c23..d33bddf 100644
--- a/src/Function.test.ts
+++ b/src/Function.test.ts
@@ -8,6 +8,14 @@ describe("Expression", () => {
   it("should produce valid SQL", () => {
     expect(Fn.sum("foo").toSQL(flavor)).toEqual("SUM(`foo`)");
     expect(Fn.max("foo").toSQL(flavor)).toEqual("MAX(`foo`)");
+    expect(Fn.add("foo", "blah").toSQL(flavor)).toEqual("(`foo` + `blah`)");
+    expect(Fn.subtract("foo", "blah").toSQL(flavor)).toEqual(
+      "(`foo` - `blah`)"
+    );
+    expect(Fn.multiply("foo", "blah").toSQL(flavor)).toEqual(
+      "(`foo` * `blah`)"
+    );
+    expect(Fn.divide("foo", "blah").toSQL(flavor)).toEqual("(`foo` / `blah`)");
     expect(Fn.ifnull("foo", `123`).toSQL(flavor)).toEqual("IFNULL(`foo`,123)");
     expect(Fn.ifnull("foo", Q.S`123`).toSQL(flavor)).toEqual(
       'IFNULL(`foo`,"123")'
diff --git a/src/Function.ts b/src/Function.ts
index 8500905..ae68f02 100644
--- a/src/Function.ts
+++ b/src/Function.ts
@@ -9,6 +9,26 @@ const formatDayjs = (dayjs: Dayjs) => dayjs.format("YYYY-MM-DD");
 const defaultFlavor = new MySQLFlavor();
 
 export const Function = {
+  add: (...columns: ExpressionValue[]) => {
+    return Q.expr(
+      `(${columns.map((v) => Expression.escapeExpressionValue(v)).join(" + ")})`
+    );
+  },
+  subtract: (...columns: ExpressionValue[]) => {
+    return Q.expr(
+      `(${columns.map((v) => Expression.escapeExpressionValue(v)).join(" - ")})`
+    );
+  },
+  divide: (...columns: ExpressionValue[]) => {
+    return Q.expr(
+      `(${columns.map((v) => Expression.escapeExpressionValue(v)).join(" / ")})`
+    );
+  },
+  multiply: (...columns: ExpressionValue[]) => {
+    return Q.expr(
+      `(${columns.map((v) => Expression.escapeExpressionValue(v)).join(" * ")})`
+    );
+  },
   sum: (column: ExpressionValue) => {
     return Q.expr(`SUM(${Expression.escapeExpressionValue(column)})`);
   },