SQL schema diagram (D2)
The sql_table shape turns D2 into a perfectly good schema diagramming tool, with primary and foreign key constraints marked.
#What this example shows
shape: sql_table, with a type per column.
constraint: primary_key and foreign_key markers.
Connections drawn between specific columns.
#A worked example
Open it, edit it, or copy the source below.
The source, which you can paste into a new diagram and edit:
direction: right
customers: {
shape: sql_table
id: uuid {constraint: primary_key}
email: text {constraint: unique}
name: text
created_at: timestamptz
}
orders: {
shape: sql_table
id: uuid {constraint: primary_key}
customer_id: uuid {constraint: foreign_key}
status: text
total: numeric(10,2)
placed_at: timestamptz
}
order_items: {
shape: sql_table
id: uuid {constraint: primary_key}
order_id: uuid {constraint: foreign_key}
product_id: uuid {constraint: foreign_key}
quantity: int
unit_price: numeric(10,2)
}
products: {
shape: sql_table
id: uuid {constraint: primary_key}
sku: text {constraint: unique}
name: text
price: numeric(10,2)
}
customers.id -> orders.customer_id
orders.id -> order_items.order_id
products.id -> order_items.product_id
#Making it your own
Connect specific columns, not whole tables; the diagram is far clearer for it.
Constraints are markers, not validation. They document intent.
For a schema that generates DDL, DBML is the better tool.
Nesting is the whole idea.
