Data Types

The DataType enum — dialect-agnostic column types that map to concrete SQL expressions per dialect.

DataType is a dialect-agnostic enumeration of the most common SQL column types. The SQL generation layer maps each variant to the appropriate keyword for PostgreSQL, MySQL, or SQLite.

Variants

Variant	Rust syntax	Description
`Integer`	`DataType::Integer`	32-bit signed integer
`BigInt`	`DataType::BigInt`	64-bit signed integer
`SmallInt`	`DataType::SmallInt`	16-bit signed integer
`Real`	`DataType::Real`	IEEE-754 double-precision float
`Decimal(p, s)`	`DataType::Decimal(10, 2)`	Fixed-precision: `p` digits, `s` after the decimal point
`Boolean`	`DataType::Boolean`	True/false value
`Varchar(n)`	`DataType::Varchar(255)`	Variable-length text up to `n` characters
`Char(n)`	`DataType::Char(10)`	Fixed-length text of exactly `n` characters
`Text`	`DataType::Text`	Unbounded text
`Date`	`DataType::Date`	Calendar date (no time)
`Time`	`DataType::Time`	Time of day (no date)
`Timestamp`	`DataType::Timestamp`	Date + time
`Uuid`	`DataType::Uuid`	Universally unique identifier
`Bytes`	`DataType::Bytes`	Opaque binary blob
`Custom(s)`	`DataType::Custom("jsonb".into())`	Verbatim dialect-specific type string

Default values

DataType::default()         // Varchar(255) — sensible default for text columns
DataType::default_key()     // Integer — used by the converter for synthesized PK columns

Dialect mapping

`DataType`	PostgreSQL	MySQL	SQLite
`Integer`	`INTEGER`	`INT`	`INTEGER`
`BigInt`	`BIGINT`	`BIGINT`	`INTEGER`
`SmallInt`	`SMALLINT`	`SMALLINT`	`INTEGER`
`Real`	`DOUBLE PRECISION`	`DOUBLE`	`REAL`
`Decimal(p,s)`	`NUMERIC(p,s)`	`DECIMAL(p,s)`	`REAL`
`Boolean`	`BOOLEAN`	`TINYINT(1)`	`INTEGER`
`Varchar(n)`	`VARCHAR(n)`	`VARCHAR(n)`	`TEXT`
`Char(n)`	`CHAR(n)`	`CHAR(n)`	`TEXT`
`Text`	`TEXT`	`TEXT`	`TEXT`
`Date`	`DATE`	`DATE`	`TEXT`
`Time`	`TIME`	`TIME`	`TEXT`
`Timestamp`	`TIMESTAMP`	`DATETIME`	`TEXT`
`Uuid`	`UUID`	`CHAR(36)`	`TEXT`
`Bytes`	`BYTEA`	`BLOB`	`BLOB`
`Custom(s)`	verbatim	verbatim	verbatim

SQLite is dynamically typed. All date/time types collapse to TEXT, integers collapse to INTEGER, and floats to REAL. If you need precise SQLite column affinities, use Custom.

Using Custom

Custom lets you bypass the abstraction for dialect-specific types:

// PostgreSQL JSONB
m.add_attribute(
    AttributeOwner::Entity(product),
    "metadata",
    DataType::Custom("jsonb".into()),
)?;

// PostGIS geography
m.add_attribute(
    AttributeOwner::Entity(location),
    "coords",
    DataType::Custom("GEOGRAPHY(POINT, 4326)".into()),
)?;

Custom values are emitted verbatim. They are not validated and may produce invalid SQL if the string is not correct for the target dialect.

Data Types

Variants

Default values

Dialect mapping

Using Custom

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