Global Functions

The DB Interface Module provides a predefined set of global functions, which allow an application to build portable SQL expressions.

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

Table 243. Restrictions on the use of global functions with RWDBExpr
Function	Restriction
`rwdbAvg(const RWDBExpr&)`	None. Corresponds to: `AVG(expr)`
rwdbCast(const RWDBExpr&, const RWDBValue&)	None. Corresponds to:`CAST(expr AS type)`
rwdbCast(const RWDBExpr&, const RWDBValue&, const RWDBExpr&)	Same as the two-expression form, as PostgreSQL does not support this form.
rwdbCast(const RWBDExpr&, const RWDBValue&, const RWDBExpr&, const RWDBExpr&)	Same as the two-expression form, as PostgreSQL does not support this form.
`rwdbCharLength(const RWDBExpr&)`	None. Corresponds to: `CHAR_LENGTH(string)`
`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: `CURRENT_USER`
`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: `expr AS str`
rwdbPosition(const RWDBExpr&, const RWDBExpr&)	None. Corresponds to:`POSITION(expr0 IN expr1)`
`rwdbSessionUser()`	None. Corresponds to: `SESSION_USER`
rwdbSubString(const RWDBExpr&, const RWDBExpr&)	None. Corresponds to:`SUBSTR(expr0,expr1)`
rwdbSubString(const RWDBExpr&, const RWDBExpr&, const RWDBExpr&)	None. Corresponds to:`SUBSTR(expr0, expr1, expr2)`
`rwdbSum(const RWDBExpr&)`	None. Corresponds to: `SUM(expr)`
`rwdbSystemDateTime()`	None. Corresponds to: `NOW()`
`rwdbSystemUser()`	None. Corresponds to: `CURRENT_USER`
rwdbTrimLeading(const RWDBExpr&, const RWDBExpr&)	None. Corresponds to: `TRIM(LEADING expr0 FROM expr1)`
rwdbTrimTrailing(const RWDBExpr&, const RWDBExpr&)	None. Corresponds to: `TRIM(TRAILING expr0 FROM expr1)`
rwdbTrimBoth(const RWDBExpr&, const RWDBExpr&)	None. Corresponds to: `TRIM(BOTH expr0 FROM expr1)`
`rwdbUpper(const RWDBExpr&)`	None. Corresponds to: `UPPER(expr)`