GREATEST and LEAST (SQL:2023 - T054) (#8532)

* Adding SQL-compliant names to existing MAXVALUE/MINVALUE functions

Author: ChudaykinAlex

doc/sql.extensions/README.builtin_functions.txt

@@ -13,6 +13,7 @@ Authors:
     Alexey Karyakin <aleksey.karyakin@mail.ru>
     Claudio Valderrama C. <cvalde at usa.net>
     Alexander Peshkov <peshkoff@mail.ru>
+    Alexey Chudaykin <chudaykinalex@gmail.com>
 
 
 ---
@@ -568,6 +569,23 @@ Example:
 See also: CHAR_TO_UUID and UUID_TO_CHAR
 
 
+--------
+GREATEST
+--------
+
+Function:
+    Returns the maximum value of a list of values.
+
+Format:
+    GREATEST( <value> [, <value> ...] )
+
+Example:
+    select greatest(v1, v2, 10) from x;
+
+Notes:
+    This function is a SQL-compliant alias to the MAXVALUE function. They work identically.
+
+
 ----
 HASH
 ----
@@ -630,6 +648,23 @@ Example:
     select last_day(of week from date '2017-11-01') from rdb$database;
 
 
+-----
+LEAST
+-----
+
+Function:
+    Returns the minimun value of a list of values.
+
+Format:
+    LEAST( <value> [, <value> ...] )
+
+Example:
+    select least(v1, v2, 10) from x;
+
+Notes:
+    This function is a SQL-compliant alias to the MINVALUE function. They work identically.
+
+
 ----
 LEFT
 ----
@@ -778,6 +813,7 @@ Examples:
 		 where rdb$db_key >= make_dbkey('SOMETABLE', 0, 0, 5)
 		   and rdb$db_key <  make_dbkey('SOMETABLE', 0, 1, 5)
 
+
 --------
 MAXVALUE
 --------
@@ -791,20 +827,26 @@ Format:
 Example:
     select maxvalue(v1, v2, 10) from x;
 
+Notes:
+    This function is a legacy name for the SQL-compliant GREATEST function. They work identically.
+
 
 --------
 MINVALUE
 --------
 
 Function:
-    Returns the minimun value of a list of values.
+    Returns the minimum value of a list of values.
 
 Format:
     MINVALUE( <value> [, <value> ...] )
 
 Example:
     select minvalue(v1, v2, 10) from x;
 
+Notes:
+    This function is a legacy name for the SQL-compliant LEAST function. They work identically.
+
 
 ---
 MOD

doc/sql.extensions/README.keywords

@@ -396,6 +396,8 @@ Firebird 6.0
   Added as reserved words:
 
 	CALL
+    GREATEST
+    LEAST
 
   Added as non-reserved words:
 

src/common/ParserTokens.h

@@ -237,6 +237,7 @@ PARSER_TOKEN(TOK_GEN_UUID, "GEN_UUID", true)
 PARSER_TOKEN(TOK_GLOBAL, "GLOBAL", false)
 PARSER_TOKEN(TOK_GRANT, "GRANT", false)
 PARSER_TOKEN(TOK_GRANTED, "GRANTED", true)
+PARSER_TOKEN(TOK_GREATEST, "GREATEST", false)
 PARSER_TOKEN(TOK_GROUP, "GROUP", false)
 PARSER_TOKEN(TOK_HASH, "HASH", true)
 PARSER_TOKEN(TOK_HAVING, "HAVING", false)
@@ -275,6 +276,7 @@ PARSER_TOKEN(TOK_LAST_VALUE, "LAST_VALUE", true)
 PARSER_TOKEN(TOK_LASTNAME, "LASTNAME", true)
 PARSER_TOKEN(TOK_LEAD, "LEAD", true)
 PARSER_TOKEN(TOK_LEADING, "LEADING", false)
+PARSER_TOKEN(TOK_LEAST, "LEAST", false)
 PARSER_TOKEN(TOK_LEAVE, "LEAVE", true)
 PARSER_TOKEN(TOK_LEFT, "LEFT", false)
 PARSER_TOKEN(TOK_LEGACY, "LEGACY", true)

src/dsql/parse.y

@@ -710,6 +710,8 @@ using namespace Firebird;
 %token <metaNamePtr> NAMED_ARG_ASSIGN
 %token <metaNamePtr> RTRIM
 %token <metaNamePtr> UNLIST
+%token <metaNamePtr> GREATEST
+%token <metaNamePtr> LEAST
 
 // precedence declarations for expression evaluation
 
@@ -4595,6 +4597,8 @@ keyword_or_column
 	| CALL
 	| LTRIM
 	| RTRIM
+	| GREATEST
+	| LEAST
 	;
 
 col_opt
@@ -8659,8 +8663,10 @@ system_function_std_syntax
 	| EXP
 	| FLOOR
 	| GEN_UUID
+	| GREATEST
 	| HEX_DECODE
 	| HEX_ENCODE
+	| LEAST
 	| LEFT
 	| LN
 	| LOG

src/jrd/SysFunction.cpp

@@ -6950,10 +6950,12 @@ const SysFunction SysFunction::functions[] =
 		{"FIRST_DAY", 2, 2, true, setParamsFirstLastDay, makeFirstLastDayResult, evlFirstLastDay, (void*) funFirstDay},
 		{"FLOOR", 1, 1, true, setParamsDblDec, makeCeilFloor, evlFloor, NULL},
 		{"GEN_UUID", 0, 1, false, NULL, makeUuid, evlGenUuid, NULL},
+		{"GREATEST", 1, -1, true, setParamsFromList, makeFromListResult, evlMaxMinValue, (void*) funMaxValue},
 		{"HASH", 1, 2, true, setParamsHash, makeHash, evlHash, NULL},
 		{"HEX_DECODE", 1, 1, true, NULL, makeDecodeHex, evlDecodeHex, NULL},
 		{"HEX_ENCODE", 1, 1, true, NULL, makeEncodeHex, evlEncodeHex, NULL},
 		{"LAST_DAY", 2, 2, true, setParamsFirstLastDay, makeFirstLastDayResult, evlFirstLastDay, (void*) funLastDay},
+		{"LEAST", 1, -1, true, setParamsFromList, makeFromListResult, evlMaxMinValue, (void*) funMinValue},
 		{"LEFT", 2, 2, true, setParamsSecondInteger, makeLeftRight, evlLeft, NULL},
 		{"LN", 1, 1, true, setParamsDblDec, makeDblDecResult, evlLnLog10, (void*) funLnat},
 		{"LOG", 2, 2, true, setParamsDblDec, makeDblDecResult, evlLog, NULL},