Datatypes

SourcePro : DB Access Module for Microsoft SQL Server User’s Guide : Technical Information : Datatypes

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 1, 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 2.

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 Guide.

NOTE: 	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 1 – 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	Long/UnsignedLong (32-bit architectures) Int/UnsignedInt (64-bit architectures)	long int / unsigned long int (32-bit architectures) int / unsigned int (64-bit architectures)
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 smalldatetime¹	SQL_TYPE_TIMESTAMP	DateTime	RWDateTime

¹ Values of type datetime and smalldatetime are affected by the time zone setting on either RWDBDatabase or RWDBConnection while sending and retrieving data. The time zone setting can be set programmatically with the timeZone() method in each of these classes.

Table 2 – 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