DB Access Module for Sybase User’s Guide : Chapter 2 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 Sybase converts the Sybase-specific datatype information provided by the database 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 Sybase maps the given RWDBValue::ValueType into a Sybase-specific type. 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.
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Table 1 – Datatype mapping when retrieving data 
Adaptive Server Datatypes
RWDBValue::ValueType
C++ Datatype
char(n)
varchar(n)
text
String
nchar(n)
nvarchar(n)
MBString1
unichar(n), univarchar(n)
unitext
UString
binary(n)
varbinary(n)
image
timestamp
Blob
bit
tinyint
smallint
Short
short int
int
Long
long int
decimal(p,0) p <= 9
numeric(p,0) p <= 9
Long
long int
decimal(p,0) 10 <= p < 19
numeric(p,0) 10 <= p < 19
LongLong
long long
decimal(p,0) p >= 19
numeric(p,0) p >= 19
Decimal
decimal(p,s)
numeric(p,s)
Decimal
float(p)
double precision
Double
double
real
Float
float
money
smallmoney
Decimal
datetime
smalldatetime2
DateTime
1 The Sybase Adaptive Server usertype value, when available, is used to differentiate standard and national character strings. See “Internationalization and Localization” on internationalization.

2 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
Adaptive Server Datatype
Char
UnsignedChar
Tiny
UnsignedTiny
tinyint
String
if 0 < length <= 255, varchar using the storageLength of the RWDBColumn, otherwise text
WString
MBString
if 0 < length <= 255, nvarchar using the storageLength of the RWDBColumn, otherwise text
UString
univarchar, using the storageLength of the RWDBColumn
Blob
if 0 < length <= 255, varbinary using the storageLength of the RWDBColumn, otherwise image
Short
UnsignedShort
smallint
Int
UnsignedInt
int
Long
UnsignedLong
int
Float
real
Double
float(p), using precision of column
Decimal
money or decimal(p,s) using precision and scale of column. See below.
Date
DateTime
datetime
Duration
Not supported by the Sybase client
Restrictions on the Use of Datatypes
Sybase Open Client Client-Library and Sybase Adaptive Server Enterprise place restrictions on the use of certain datatypes. Where possible, the DB Interface Module is flexible about datatypes. However, there are some situations where conversions are not possible, and in these cases your application must be aware of the contexts in which certain datatypes can be used. Table 3 outlines the restrictions associated with each DB Interface Module type.
Table 3 – Restrictions on the use of DB Interface Module datatypes
RWDBValue::ValueType
Restrictions
Char
UnsignedChar
No restrictions
String
WString
MBString
UString
Not supported on RWDBBoundExpr if string size is bigger than 16384 bytes
Blob
Not supported on RWDBBoundExpr
Short
UnsignedShort
No restrictions
Int
UnsignedInt
No restrictions
Long
UnsignedLong
No restrictions
Double
No restrictions
Float
No restrictions
Decimal
The precision and scale of a value can vary depending on the version of the Sybase client and server. Consistent versions of clients and servers can eliminate difficulties in conversions.
Date
No restrictions
DateTime
Supports dates ranging from January 1, 1753 through December 31, 9999, 23:59:59.999. However, accuracy is limited to 3.33 milliseconds by Sybase. Therefore, the maximum date that could be inserted is December 31, 9999, 23:59:59.996.
TimeTuple
No restrictions
TimeTupleOffset
Not supported
Duration
Not supported by the Sybase client
LongLong
UnsignedLongLong
Table creation not supported
LongDouble
No restrictions