feat: changed backend-pg to backend

backend/src/db/utils.ts

@@ -0,0 +1,45 @@
+import { Knex } from "knex";
+
+import { TableName } from "./schemas";
+
+export const createJunctionTable = (
+  knex: Knex,
+  tableName: TableName,
+  table1Name: TableName,
+  table2Name: TableName
+) =>
+  knex.schema.createTable(tableName, (table) => {
+    table.uuid("id", { primaryKey: true }).defaultTo(knex.fn.uuid());
+    table.uuid(`${table1Name}Id`).unsigned().notNullable(); // Foreign key for table1
+    table.uuid(`${table2Name}Id`).unsigned().notNullable(); // Foreign key for table2
+    table.foreign(`${table1Name}Id`).references("id").inTable(table1Name).onDelete("CASCADE");
+    table.foreign(`${table2Name}Id`).references("id").inTable(table2Name).onDelete("CASCADE");
+  });
+
+// one time logic
+// this is a postgres function log to set updateAt to present time whenever row gets updated
+export const createUpdateAtTriggerFunction = (knex: Knex) =>
+  knex.raw(`
+CREATE OR REPLACE FUNCTION on_update_timestamp() RETURNS TRIGGER AS $$ BEGIN NEW."updatedAt" = NOW();
+RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+`);
+
+export const dropUpdatedAtTriggerFunction = (knex: Knex) =>
+  knex.raw(`
+DROP FUNCTION IF EXISTS on_update_timestamp() CASCADE;
+`);
+
+// we would be using this to apply updatedAt where ever we wanta
+// remember to set `timestamps(true,true,true)` before this on schema
+export const createOnUpdateTrigger = (knex: Knex, tableName: string) =>
+  knex.raw(`
+CREATE TRIGGER "${tableName}_updatedAt"
+BEFORE UPDATE ON ${tableName}
+FOR EACH ROW
+EXECUTE PROCEDURE on_update_timestamp();
+`);
+
+export const dropOnUpdateTrigger = (knex: Knex, tableName: string) =>
+  knex.raw(`DROP TRIGGER IF EXISTS "${tableName}_updatedAt" ON ${tableName}`);