Enum odbc_api::handles::DataType

pub enum DataType {
    Unknown,
    Char {
        length: usize,
    },
    WChar {
        length: usize,
    },
    Numeric {
        precision: usize,
        scale: i16,
    },
    Decimal {
        precision: usize,
        scale: i16,
    },
    Integer,
    SmallInt,
    Float {
        precision: usize,
    },
    Real,
    Double,
    Varchar {
        length: usize,
    },
    WVarchar {
        length: usize,
    },
    LongVarchar {
        length: usize,
    },
    LongVarbinary {
        length: usize,
    },
    Date,
    Time {
        precision: i16,
    },
    Timestamp {
        precision: i16,
    },
    BigInt,
    TinyInt,
    Bit,
    Varbinary {
        length: usize,
    },
    Binary {
        length: usize,
    },
    Other {
        data_type: SqlDataType,
        column_size: usize,
        decimal_digits: i16,
    },
}

The relational type of the column. Think of it as the type used in the CREATE TABLE statement then creating the database.

There might be a mismatch between the types supported by your database and the types defined in ODBC. E.g. ODBC does not have a timestamp with timezone type, theras Postgersql and Microsoft SQL Server both have one. In such cases it is up to the specific ODBC driver what happens. Microsoft SQL Server return a custom type, with its meaning specific to that driver. PostgreSQL identifies that column as an ordinary ODBC timestamp. Enumeration over valid SQL Data Types supported by ODBC

Variants

Unknown

The type is not known.

Char

Fields

length: usize

Column size in characters (excluding terminating zero).

Char(n). Character string of fixed length.

WChar

Fields

length: usize

Column size in characters (excluding terminating zero).

NChar(n). Character string of fixed length.

Numeric

Fields

precision: usize

Total number of digits.

scale: i16

Number of decimal digits.

`Numeric(p,s). Signed, exact, numeric value with a precision p and scale s (1 <= p <= 15; s <= p)

Decimal

Fields

precision: usize

Total number of digits.

scale: i16

Number of decimal digits.

Decimal(p,s). Signed, exact, numeric value with a precision of at least p and scale s. The maximum precision is driver-defined. (1 <= p <= 15; s <= p)

Integer

Integer. 32 Bit Integer

SmallInt

Smallint. 16 Bit Integer

Float

Fields

precision: usize

Float(p). Signed, approximate, numeric value with a binary precision of at least p. The maximum precision is driver-defined.

Depending on the implementation binary precision is either 24 (f32) or 53 (f64).

Real

Real. Signed, approximate, numeric value with a binary precision 24 (zero or absolute value 10^-38] to 10^38).

Double

Double Precision. Signed, approximate, numeric value with a binary precision 53 (zero or absolute value 10^-308 to 10^308).

Varchar

Fields

length: usize

Maximum length of the character string (excluding terminating zero). Wether this length is to be interpreted as bytes or Codepoints is ambigious and depends on the datasource.

E.g. For Microsoft SQL Server this is the binary length, theras for a MariaDB this refers to codepoints in case of UTF-8 encoding. If you need the binary size query the octet length for that column instead.

To find out how to interpret this value for a particular datasource you can use the odbcsv command line tool list-columns subcommand and query a Varchar column. If the buffer/octet length matches the column size, you can interpret this as the byte length.

Varchar(n). Variable length character string.

WVarchar

Fields

length: usize

Maximum length of the character string (excluding terminating zero).

NVARCHAR(n). Variable length character string. Indicates the use of wide character strings and use of UCS2 encoding on the side of the database.

LongVarchar

Fields

length: usize

Maximum length of the character string (excluding terminating zero). Maximum size depends on the capabilities of the driver and datasource. E.g. its 2^31 - 1 for MSSQL.

TEXT. Variable length characeter string for long text objects.

LongVarbinary

Fields

length: usize

Maximum length of the binary data. Maximum size depends on the capabilities of the driver and datasource.

BLOB. Variable length data for long binary objects.

Date

Date. Year, month, and day fields, conforming to the rules of the Gregorian calendar.

Time

Fields

precision: i16

Number of radix ten digits used to represent the timestamp after the decimal points. E.g. Milliseconds would be represented by precision 3, Microseconds by 6 and Nanoseconds by 9.

Time. Hour, minute, and second fields, with valid values for hours of 00 to 23, valid values for minutes of 00 to 59, and valid values for seconds of 00 to 61. Precision p indicates the seconds precision.

Timestamp

Fields

precision: i16

Number of radix ten digits used to represent the timestamp after the decimal points. E.g. Milliseconds would be represented by precision 3, Microseconds by 6 and Nanoseconds by 9.

Timestamp. Year, month, day, hour, minute, and second fields, with valid values as defined for the Date and Time variants.

BigInt

BIGINT. Exact numeric value with precision 19 (if signed) or 20 (if unsigned) and scale 0 (signed: -2^63 <= n <= 2^63 - 1, unsigned: 0 <= n <= 2^64 - 1). Has no corresponding type in SQL-92.

TinyInt

TINYINT. Exact numeric value with precision 3 and scale 0 (signed: -128 <= n <= 127, unsigned: 0 <= n <= 255)

Bit

BIT. Single bit binary data.

Varbinary

Fields

length: usize

VARBINARY(n). Type for variable sized binary data.

Binary

Fields

length: usize

BINARY(n). Type for fixed sized binary data.

Other

Fields

data_type: SqlDataType

Type of the column

column_size: usize

Size of column element

decimal_digits: i16

Decimal digits returned for the column element. Exact meaning if any depends on the data_type field.

The driver returned a type, but it is not among the other types of these enumeration. This is a catchall, in case the library is incomplete, or the data source supports custom or non-standard types.

Implementations

impl DataType

pub fn new( data_type: SqlDataType, column_size: usize, decimal_digits: i16 ) -> Self

This constructor is useful to create an instance of the enumeration using values returned by ODBC Api calls like SQLDescribeCol, rather than just initializing a variant directly.

pub fn data_type(&self) -> SqlDataType

The associated data_type discriminator for this variant.

pub fn column_size(&self) -> usize

Return the column size, as it is required to bind the data type as a parameter. This implies

pub fn decimal_digits(&self) -> i16

Return the number of decimal digits as required to bind the data type as a parameter.

pub fn display_size(&self) -> Option<usize>

The maximum number of characters needed to display data in character form.

See: https://docs.microsoft.com/en-us/sql/odbc/reference/appendixes/display-size

pub fn utf8_len(&self) -> Option<usize>

The maximum length of the UTF-8 representation in bytes.

use odbc_api::DataType;
// Character set data types length is multiplied by four.
assert_eq!(DataType::Varchar { length: 10 }.utf8_len(), Some(40));
assert_eq!(DataType::Char { length: 10 }.utf8_len(), Some(40));
assert_eq!(DataType::WVarchar { length: 10 }.utf8_len(), Some(40));
assert_eq!(DataType::WChar { length: 10 }.utf8_len(), Some(40));
// For other types return value is identical to display size as they are assumed to be
// entirely representable with ASCII characters.
assert_eq!(DataType::Numeric { precision: 10, scale: 3}.utf8_len(), Some(10 + 2));

pub fn utf16_len(&self) -> Option<usize>

The maximum length of the UTF-16 representation in 2-Byte characters.

use odbc_api::DataType;
// Character set data types length is multiplied by two.
assert_eq!(DataType::Varchar { length: 10 }.utf16_len(), Some(20));
assert_eq!(DataType::Char { length: 10 }.utf16_len(), Some(20));
assert_eq!(DataType::WVarchar { length: 10 }.utf16_len(), Some(20));
assert_eq!(DataType::WChar { length: 10 }.utf16_len(), Some(20));
// For other types return value is identical to display size as they are assumed to be
// entirely representable with ASCII characters.
assert_eq!(DataType::Numeric { precision: 10, scale: 3}.utf16_len(), Some(10 + 2));

Trait Implementations

impl Clone for DataType

fn clone(&self) -> DataType

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DataType

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DataType

fn default() -> DataType

Returns the “default value” for a type.

impl PartialEq<DataType> for DataType

fn eq(&self, other: &DataType) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for DataType

impl Eq for DataType

impl StructuralEq for DataType

impl StructuralPartialEq for DataType