2.3 Datatypes

DBTools.h++ stores data fetched from a database into a DBTools.h++ application in instances of the RWDBValue class. Most applications can ignore RWDBValue, and fetch data directly into C++ variables. For applications that do need to use it, Table 1 shows how DB2 SQL symbolic datatypes are mapped onto RWDBValue types, and lists the C++ class or datatype appropriate for each DB2 SQL symbolic datatype.

Table 1 -- Type mapping when retrieving data

DB2 SQL symbolic datatype	RWDBValue:: ValueType	C++ datatype
`SQL_CHAR; SQL_VARCHAR; SQL_LONGVARCHAR; SQL_CLOB`	`String`	*RWCString*
`SQL_BINARY; SQL_VARBINARY; SQL_LONGVARBINARY; SQL_BLOB`	`Blob`	*RWDBBlob*
`SQL_SMALLINT`	`Short`	`short int`
`SQL_INTEGER`	`Long`	`long int`
`SQL_DOUBLE`	`Double`	`double`
`SQL_REAL, SQL_FLOAT`	`Float`	`float`
`SQL_DATE`	`Date`	*RWDate*
`SQL_NUMERIC; SQL_DECIMAL`	`Decimal`	*RWDecimalPortable*
`SQL_TIMESTAMP SQL_TIME`	`DateTime`	*RWDBDateTime*

NOTE: The current release of the DB2 access library does not support the following DB2 SQL data types:
BLOB LOCATOR, CLOB LOCATOR, DBCLOB, DBCLOB LOCATOR, GRAPHIC, LONG VARGRAPHIC and VARGRAPHIC.

When an application uses DBTools.h++ to create a table, RWDBValue::ValueType functions are used to define the table's schema. Table 2 shows how DBTools.h++ maps its datatypes to DB2 SQL symbolic data types when defining a schema.

Table 2 -- Type mapping when creating tables

RWDBValue::ValueType	DB2 SQL symbolic datatype
`Char`, `UnsignedChar`	`SQL_SMALLINT`
`String`	`SQL_VARCHAR if 0 < length <= 4000;` `SQL_CLOB if 4000 < length <= 2,147,483,647;`
WString, MBString	Not supported
`Blob`	`SQL_BLOB`
`Short`, `UnsignedShort`	`SQL_SMALLINT`
`Int`, `UnsignedInt`	`SQL_INTEGER`
`Long`, `UnsignedLong`	`SQL_INTEGER`
`Float`	`SQL_FLOAT`
`Double`	`SQL_DOUBLE`
`Decimal`	`SQL_DECIMAL`
`Date`	`SQL_DATE`
`DateTime`	`SQL_TIMESTAMP`
Duration	SQL_TIME