2.3 Expressions

Due to limitations in SQL servers, there are some restrictions on the use of DBTools.h++ expressions. These are covered in the following section.

2.3.1 Global Functions

Table 4 lists restrictions on the global functions associated with RWDBExpr.

Table 4 -- Restrictions on the use of global functions with RWDBExpr

Function	Restrictions
`rwdbAvg(const RWDBExpr&)`	None. Corresponds to: `AVG(expr)`
`rwdbCast(const RWDBExpr&, const RWDBValue&)`	None. Corresponds to: `CONVERT(val, expr)`
`rwdbCast(const RWDBExpr&, const RWDBValue&, const RWDBExpr&)`	None. Corresponds to: `CONVERT(val, expr0, expr2)`
`rwdbCast(const RWBDExpr&, const RWDBValue&, const RWDBExpr&, const RWDBExpr&)`	The fourth parameter is not supported, effectively supporting only the three-parameter version of `CONVERT()`
`rwdbCharLength(const RWDBExpr&)`	None. Corresponds to: `CHAR_LENGTH(expr)`
`rwdbCount()`	None. Corresponds to: `COUNT(*)`
`rwdbCount(const RWDBExpr&)`	None. Corresponds to: `COUNT(expr)`
`rwdbCountDistinct(const RWDBExpr&)`	None. Corresponds to: `COUNT(DISTINCT(expr))`
`rwdbCurrentUser()`	None. Corresponds to: `USER_NAME()`
`rwdbExists(const RWDBSelectorBase&)`	None. Corresponds to: `EXISTS(sel)`
`rwdbLower(const RWDBExpr&)`	None. Corresponds to: `LOWER(expr)`
`rwdbMax(const RWDBExpr&)`	None. Corresponds to: `MAX(expr)`
`rwdbMin(const RWDBExpr&)`	None. Corresponds to: `MIN(expr)`
`rwdbName(const RWCString&, const RWDBExpr&)`	None. Corresponds to: `string = expr`
`rwdbPosition(const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `CHARINDEX(expr0, expr1)`
`rwdbSessionUser()`	None. Corresponds to: `USER_NAME()`
`rwdbSubString(const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `SUBSTRING(expr0, expr1, 256)`
`rwdbSubString(const RWDBExpr&, const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `SUBSTRING(expr0, expr1, expr2)`
`rwdbSum(const RWDBExpr&)`	None. Corresponds to: `SUM(expr)`
rwdbSystemDateTime()	None. Corresponds to: `GETDATE()`
`rwdbSystemUser()`	None. Corresponds to: `SUSER_NAME()`
`rwdbTrimLeading(const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `LTRIM(expr1)`, removing blanks
`rwdbTrimTrailing(const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `RTRIM(expr1)`, removing blanks
`rwdbTrimBoth(const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `LTRIM(RTRIM(expr1))`, removing blanks
`rwdbUpper(const RWDBExpr&)`	None. Corresponds to: `UPPER(expr)`