diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/parse.y | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/src/parse.y b/src/parse.y index 72c1b66cf..138a41d30 100644 --- a/src/parse.y +++ b/src/parse.y @@ -1184,7 +1184,23 @@ expr(A) ::= idj(X) LP STAR RP. { %ifdef SQLITE_ENABLE_ORDERED_SET_FUNCS %include { - /* Generate an expression node that represents an ordered-set aggregate function */ + /* Generate an expression node that represents an ordered-set aggregate function. + ** + ** SQLite does not do anything special to evaluate ordered-set aggregates. The + ** aggregate function itself is expected to do any required ordering on its own. + ** This is just syntactic sugar. + ** + ** This syntax: percentile(f) WITHIN GROUP ( ORDER BY y ) + ** + ** Is equivalent to: percentile(y,f) + ** + ** The purpose of this function is to generate an Expr node from the first syntax + ** into a TK_FUNCTION node that looks like it came from the second syntax. + ** + ** Only functions that have the SQLITE_SELFORDER1 perperty are allowed to do this + ** transformation. Because DISTINCT is not allowed in the ordered-set aggregate + ** syntax, an error is raised if DISTINCT is used. + */ static Expr *sqlite3ExprAddOrderedsetFunction( Parse *pParse, /* Parsing context */ Token *pFuncname, /* Name of the function */ @@ -1213,7 +1229,7 @@ expr(A) ::= idj(X) LP STAR RP. { if( pDef==0 || (pDef->funcFlags & SQLITE_SELFORDER1)==0 ){ sqlite3ErrorMsg(pParse, "%#T() is not an ordered-set aggregate", pExpr); }else if( isDistinct==SF_Distinct ){ - sqlite3ErrorMsg(pParse, "DISTINCT not allows on ordered-set aggregate %T()", + sqlite3ErrorMsg(pParse, "DISTINCT not allowed on ordered-set aggregate %T()", pFuncname); } } |