Map SQL Numeric Types to Prisma Int, Float, Decimal, and BigInt

Numeric Type Mapping

SQL has a rich set of numeric types with different ranges and precision. Prisma provides four numeric scalar types: Int, BigInt, Float, and Decimal. The converter selects the appropriate type based on the SQL column definition.

Example SQL

CREATE TABLE products (
  id SERIAL PRIMARY KEY,
  quantity INTEGER NOT NULL DEFAULT 0,
  views BIGINT NOT NULL DEFAULT 0,
  price DECIMAL(10, 2) NOT NULL,
  weight DOUBLE PRECISION,
  rating REAL
);

Generated Prisma Schema

model Product {
  id       Int      @id @default(autoincrement())
  quantity Int      @default(0)
  views    BigInt   @default(0)
  price    Decimal  @db.Decimal(10, 2)
  weight   Float?   @db.DoublePrecision
  rating   Float?   @db.Real

  @@map("products")
}

Type Mapping Table

SQL type	Prisma type	Notes
INTEGER / INT	Int	32-bit signed integer
SMALLINT	Int	@db.SmallInt annotation
BIGINT / BIGSERIAL	BigInt	64-bit, serialized as string in JSON
DECIMAL(p,s) / NUMERIC(p,s)	Decimal	Exact precision for money
REAL / FLOAT4	Float	@db.Real — 32-bit floating point
DOUBLE PRECISION / FLOAT8	Float	@db.DoublePrecision — 64-bit
MONEY	Decimal	PostgreSQL-specific

Decimal for Money

Always use Decimal (not Float) for monetary values. Floating-point arithmetic introduces rounding errors that accumulate over many transactions. The Decimal type in Prisma maps to a JavaScript Decimal.js instance in the client, providing exact arithmetic.

price    Decimal @db.Decimal(10, 2)
discount Decimal @db.Decimal(5, 2)
tax      Decimal @db.Decimal(10, 2)

BigInt Serialization

BigInt fields are serialized as strings in JSON because JavaScript Number cannot safely represent integers larger than 2^53 - 1. When consuming BigInt values via the Prisma client, remember to handle the string representation in your API responses.

Default Values

Numeric defaults map directly:

SQL default	Prisma default
DEFAULT 0	@default(0)
DEFAULT 1.5	@default(1.5)
DEFAULT nextval('seq')	@default(autoincrement())

Unsigned Integers (MySQL)

MySQL supports UNSIGNED integers. Prisma does not have a native unsigned type, so the converter uses @db.UnsignedInt, @db.UnsignedBigInt, etc., to preserve the database constraint.