Datatypes

The classes RWDBColumn and RWDBValue have an associated RWDBValue::ValueType that specifies the datatype of the database column or field being referenced. Mapping between this datatype and the database vendor type runs in both directions:

When fetching data or retrieving information about tables, the DB Access Module for Microsoft SQL Server converts the SQL type code provided by the Microsoft SQL Server ODBC driver into RWDBValue::ValueTypes. This mapping is shown in Table 208, which also gives the C++ datatype corresponding to the RWDBValue::ValueType.

When creating tables, the DB Access Module for Microsoft SQL Server maps the given RWDBValue::ValueType directly to the Microsoft SQL Server datatype. This mapping is shown in Table 209.

The RWDBValue::ValueTypes, accessible through the type() method, are uniform across all Access Modules. For a complete explanation of the DB Interface Module data model, see Chapter 7, "The Data Model," in the DB Interface Module User’s Guide, and RWDBValue in the SourcePro API Reference.

We update the mapping tables regularly, but Rogue Wave cannot be responsible for changes made by other vendors. For the latest information on mappings between the Microsoft SQL Server SQL symbolic datatypes and the actual SQL datatypes used on the database, please consult Microsoft's SQL Server Library documentation.

Table 208. Datatype mapping when retrieving data
SQL Server Datatype	ODBC SQL Datatype	RWDBValue:: ValueType	C++ Datatype
`char(n)` `varchar(n)` `text`	`SQL_CHAR` `SQL_VARCHAR` `SQL_LONGVARCHAR`	`String`	RWCString
`nchar(n)` `nvarchar(n)` `ntext`	`SQL_WCHAR` `SQL_WVARCHAR` `SQL_WLONGVARCHAR`	`UString`	RWBasicUString or RWUString
`binary(n)` `varbinary(n)` `image`	`SQL_BINARY` `SQL_VARBINARY` `SQL_LONGVARBINARY`	`Blob`	RWDBBlob
`bit`	`SQL_BIT`	`UnsignedChar`	`unsigned char`
`tinyint`	`SQL_TINYINT`	`UnsignedChar`	`unsigned char`
`smallint`	`SQL_SMALLINT`	`Short`	`short int`
`bigint`	`SQL_BIGINT`	`LongLong`	`long long`
`int`	`SQL_INTEGER`	`Int/UnsignedInt`	`int / unsigned int`
`float(p)`	`SQL_FLOAT`	`Double`	`double`
`real`	`SQL_REAL`	`Float`	`float`
`decimal(p,s)` `money` `smallmoney`	`SQL_DECIMAL`	`Decimal`	RWDecimalPortable
`timestamp`	`SQL_BINARY`	`Blob`	RWDBBlob
`datetime` `smalldatetime`1	`SQL_TYPE_TIMESTAMP`	`DateTime`	RWDateTime

Table 209. Datatype mapping when creating tables
RWDBValue:: ValueType	SQL Server Datatype
`Blob`	if 0 < `length` <= 8000 `varbinary` using the storageLength of the RWDBColumn, otherwise `image`
`Char` `UnsignedChar` `Tiny` `UnsignedTiny`	`tinyint`
`Date` `DateTime`	`datetime`
`Decimal`	`decimal(p,s)` using `precision` and `scale` of the RWDBColumn supplied, otherwise `decimal(8, 0)`
`Duration`	Not supported by Microsoft SQL Server
`Float`	`real`
`Double`	`float`
`Int` `UnsignedInt`	`smallint`
`LongDouble`	Not supported by Microsoft SQL Server
`Long` `UnsignedLong`	`int`
`Short` `UnsignedShort`	`smallint`
`String`	if 0 < `length` <= 8000 bytes, `varchar` using the `storageLength` of the RWDBColumn, otherwise text
`UString` `MBString` `WString`	if 0 < `length` <= 4000 bytes, `nvarchar` using the `storageLength` of the RWDBColumn, otherwise `ntext`
`LongLong` `UnsignedLongLong`	`bigint`

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