Expand description
Traits dealing with DuckDB data types.
DuckDB uses a dynamic type system. Implementations of
the ToSql
and FromSql
traits are provided for the basic types that
DuckDB provides methods for:
- Strings (
String
and&str
) - Blobs (
Vec<u8>
and&[u8]
) - Numbers
The number situation is a little complicated due to the fact that all
numbers in DuckDB are stored as INTEGER
(i64
) or REAL
(f64
).
ToSql
and FromSql
are implemented for all primitive number types.
FromSql
has different behaviour depending on the SQL and Rust types, and
the value.
INTEGER
to integer: returns anError::IntegralValueOutOfRange
error if the value does not fit in the Rust type.REAL
to integer: always returns anError::InvalidColumnType
error.INTEGER
to float: casts usingas
operator. Never fails.REAL
to float: casts usingas
operator. Never fails.
ToSql
always succeeds except when storing a u64
or usize
value that
cannot fit in an INTEGER
(i64
). Also note that DuckDB ignores column
types, so if you store an i64
in a column with type REAL
it will be
stored as an INTEGER
, not a REAL
.
If the time
feature is enabled, implementations are
provided for time::OffsetDateTime
that use the RFC 3339 date/time format,
"%Y-%m-%dT%H:%M:%S.%fZ"
, to store time values as strings. These values
can be parsed by SQLite’s builtin
datetime functions. If you
want different storage for datetimes, you can use a newtype.
ToSql
and FromSql
are also implemented for Option<T>
where T
implements ToSql
or FromSql
for the cases where you want to know if
a value was NULL (which gets translated to None
).
Structs
Empty struct that can be used to fill in a query parameter as NULL
.
Enums
Enum listing possible errors from FromSql
trait.
An absolute length of time in seconds, milliseconds, microseconds or nanoseconds. Copy from arrow::datatypes::TimeUnit
ToSqlOutput
represents the possible output types for implementers of the
ToSql
trait.
DuckDB data types. See Fundamental Datatypes.
Owning dynamic type value. Value’s type is typically dictated by DuckDB (not by the caller).
A non-owning static type value. Typically the memory backing this value is owned by SQLite.
Traits
A trait for types that can be created from a DuckDB value.
A trait for types that can be converted into DuckDB values. Returns
[Error::ToSqlConversionFailure
] if the conversion fails.
Type Definitions
Result type for implementors of the FromSql
trait.