Other ORMs and data frameworks tend to deviate/abstract you away from SQL, which leads to a double learning curve: needing to know both SQL and the framework’s API.

Above is a statement that I read from Drizzle ORM. Which I found very interesting and relevant.

So drizzle is ORM(Object Relational Mapping) for SQL. In more simple words, think of it like middleman between backend and database. Helping you interact with the database using TS instead of raw SQL.

In drizzle **Queries done (using Drizzle-ORM) and migrations are done (using Drizzle-Kit).

Third callback function in schema.

The third callback func in table declarations is used to define indexes and constraints for the table.

	const { pgTable, serial, text } from 'drizzle-orm/pg-core'
	
	const users = pgTable('users', {
		id: serial('id').primaryKey(),
		name: text('name').notNull(),
		email: text('email').notNull().unique(),
		password: text('password').notNull(),
	},
		(users) => {
			return {
				emailIdx: uniqueIndex('email_idx').on(users.email),
			}
		}
	)

SQL/Drizzle GroupBy

It's lets you display your data in groups. It's is used with an aggregate function which combines multiple rows of data into one row.

Some aggregate func: Count(), Sum() etc.

Think of it like grouping all the same looking data. And group by clause perfom it operation in buffer(tmp storage) not directly in database.

Example

Table name is lets say Comp.
 
|----------------------|
| id | Dname   |  Sal  |
|----------------------|
| 1	 | sale    |  1500 |
|----------------------|
| 2	 | HR      |  1000 |
|----------------------|
| 3	 | sale    |  1000 |
|----------------------|
| 4	 | product |  5000 |
|----------------------|
| 5	 | HR      |  1000 |
|----------------------|
| 6	 | sale    |  4000 |
|----------------------|
 
1. we want to know, in our company how many dept are there.
command: select dname from comp group by dname;
output: sale, HR, product.
 
2. we want to know, how many sales/HR/product are there:
command: select dname, count(*) from comp group by dname;
output: sale: 3, HR: 2, product: 1
 
3. we want to know, how many by sale now.
command: select dname, count(*) from comp where comp<= 1000 group by dname;
output: HR: 2, sale: 1 
 
4. we want max salaried dept.
command: select dname, max(sal) from comp group by dname;
output: product: 5000, sale: 4000, HR: 1000

Now you can play around with bunch of other aggregate function avlb.