2.4 Expressions

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

2.4.1 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: `{fn CONVERT(expr, expr)}`
`rwdbCast(const RWDBExpr&, const RWDBValue&, const RWDBExpr&)`	Same as the two-expression form, as Microsoft SQL Server does not support this form.
`rwdbCast(const RWBDExpr&, const RWDBValue&, const RWDBExpr&, const RWDBExpr&)`	Same as the two-expression form, as Microsoft SQL Server does not support this form.
`rwdbCharLength(const RWDBExpr&)`	None. Corresponds to: `{fn 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: `{fn USER_NAME ()}`
`rwdbExists(const RWDBSelectorBase&)`	None. Corresponds to: `EXISTS sel`
`rwdbLower(const RWDBExpr&)`	None. Corresponds to: `{fn LCASE(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: `{fn LOCATE(expr, expr)}`
`rwdbSessionUser()`	None. Corresponds to: `{fn USER_NAME() }`
`rwdbSubString(const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `{fn SUBSTRING (expr0, expr1, fn LENGTH(expr0))}`
`rwdbSubString(const RWDBExpr&, const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `{fn SUBSTRING(expr0, expr1, expr2)}`
`rwdbSum(const RWDBExpr&)`	None. Corresponds to: `SUM(expr)`
rwdbSystemDateTime()	None. Corresponds to: `{ fn NOW() }`
`rwdbSystemUser()`	None. Corresponds to: `{ fn SUSER_NAME() }`
`rwdbTrimLeading(const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `LTRIM(expr1)`
`rwdbTrimTrailing(const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `RTRIM(expr1)`
`rwdbTrimBoth(const RWDBExpr&, const RWDBExpr&)`	None. Corresponds to: `LTRIM(RTRIM(expr1))`
`rwdbUpper(const RWDBExpr&)`	None. Corresponds to: `{fn UCASE(expr)}`