Some fixes in CASE.

Test suit was extended to conver various arguments mixes.

mysql-test/r/case.result

@@ -10,10 +10,10 @@ CASE "c" when "a" then 1 when "b" then 2 ELSE 3 END
 3
 select CASE BINARY "b" when "a" then 1 when "B" then 2 WHEN "b" then "ok" END;
 CASE BINARY "b" when "a" then 1 when "B" then 2 WHEN "b" then "ok" END
-0
+ok
 select CASE "b" when "a" then 1 when binary "B" then 2 WHEN "b" then "ok" END;
 CASE "b" when "a" then 1 when binary "B" then 2 WHEN "b" then "ok" END
-0
+ok
 select CASE concat("a","b") when concat("ab","") then "a" when "b" then "b" end;
 CASE concat("a","b") when concat("ab","") then "a" when "b" then "b" end
 a
@@ -72,6 +72,48 @@ yellow
 green
 drop table t1;
 SET NAMES latin1;
+CREATE TABLE t1 SELECT 
+CASE WHEN 1 THEN _latin1'a' COLLATE latin1_danish_ci ELSE _latin1'a' END AS c1,
+CASE WHEN 1 THEN _latin1'a' ELSE _latin1'a' COLLATE latin1_danish_ci END AS c2,
+CASE WHEN 1 THEN 'a' ELSE  1  END AS c3,
+CASE WHEN 1 THEN  1  ELSE 'a' END AS c4,
+CASE WHEN 1 THEN 'a' ELSE 1.0 END AS c5,
+CASE WHEN 1 THEN 1.0 ELSE 'a' END AS c6,
+CASE WHEN 1 THEN  1  ELSE 1.0 END AS c7,
+CASE WHEN 1 THEN 1.0 ELSE  1  END AS c8
+;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `c1` char(1) character set latin1 collate latin1_danish_ci default NULL,
+  `c2` char(1) character set latin1 collate latin1_danish_ci default NULL,
+  `c3` char(1) default NULL,
+  `c4` char(1) default NULL,
+  `c5` char(3) default NULL,
+  `c6` char(3) default NULL,
+  `c7` double(3,1) default NULL,
+  `c8` double(3,1) default NULL
+) TYPE=MyISAM CHARSET=latin1
+DROP TABLE t1;
+SELECT CASE 
+WHEN 1 
+THEN _latin1'a' COLLATE latin1_danish_ci 
+ELSE _latin1'a' COLLATE latin1_swedish_ci
+END;
+ERROR HY000: Illegal mix of collations (latin1_danish_ci,EXPLICIT) and (latin1_swedish_ci,EXPLICIT) for operation 'case'
+SELECT CASE _latin1'a' COLLATE latin1_general_ci
+WHEN _latin1'a' COLLATE latin1_danish_ci  THEN 1
+WHEN _latin1'a' COLLATE latin1_swedish_ci THEN 2
+END;
+ERROR HY000: Illegal mix of collations (latin1_general_ci,EXPLICIT), (latin1_danish_ci,EXPLICIT), (latin1_swedish_ci,EXPLICIT) for operation 'case'
+SELECT 
+CASE _latin1'a' COLLATE latin1_general_ci  WHEN _latin1'A' THEN '1' ELSE 2 END,
+CASE _latin1'a' COLLATE latin1_bin         WHEN _latin1'A' THEN '1' ELSE 2 END,
+CASE _latin1'a' WHEN _latin1'A' COLLATE latin1_swedish_ci THEN '1' ELSE 2 END,
+CASE _latin1'a' WHEN _latin1'A' COLLATE latin1_bin        THEN '1' ELSE 2 END
+;
+CASE _latin1'a' COLLATE latin1_general_ci  WHEN _latin1'A' THEN '1' ELSE 2 END	CASE _latin1'a' COLLATE latin1_bin         WHEN _latin1'A' THEN '1' ELSE 2 END	CASE _latin1'a' WHEN _latin1'A' COLLATE latin1_swedish_ci THEN '1' ELSE 2 END	CASE _latin1'a' WHEN _latin1'A' COLLATE latin1_bin        THEN '1' ELSE 2 END
+1	2	1	2
 CREATE TABLE t1 SELECT COALESCE(_latin1'a',_latin2'a');
 ERROR HY000: Illegal mix of collations (latin1_swedish_ci,COERCIBLE) and (latin2_general_ci,COERCIBLE) for operation 'coalesce'
 CREATE TABLE t1 SELECT COALESCE('a' COLLATE latin1_swedish_ci,'b' COLLATE latin1_bin);

mysql-test/t/case.test

@@ -42,6 +42,44 @@ insert into t1 values (1,1,'orange'),(1,2,'large'),(2,1,'yellow'),(2,2,'medium')
 select max(case col when 1 then val else null end) as color from t1 group by row;
 drop table t1;
 
+SET NAMES latin1;
+
+#
+# CASE and argument types/collations aggregation into result 
+#
+CREATE TABLE t1 SELECT 
+ CASE WHEN 1 THEN _latin1'a' COLLATE latin1_danish_ci ELSE _latin1'a' END AS c1,
+ CASE WHEN 1 THEN _latin1'a' ELSE _latin1'a' COLLATE latin1_danish_ci END AS c2,
+ CASE WHEN 1 THEN 'a' ELSE  1  END AS c3,
+ CASE WHEN 1 THEN  1  ELSE 'a' END AS c4,
+ CASE WHEN 1 THEN 'a' ELSE 1.0 END AS c5,
+ CASE WHEN 1 THEN 1.0 ELSE 'a' END AS c6,
+ CASE WHEN 1 THEN  1  ELSE 1.0 END AS c7,
+ CASE WHEN 1 THEN 1.0 ELSE  1  END AS c8
+;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+--error 1265
+SELECT CASE 
+  WHEN 1 
+  THEN _latin1'a' COLLATE latin1_danish_ci 
+  ELSE _latin1'a' COLLATE latin1_swedish_ci
+  END;
+
+--error 1268
+SELECT CASE _latin1'a' COLLATE latin1_general_ci
+  WHEN _latin1'a' COLLATE latin1_danish_ci  THEN 1
+  WHEN _latin1'a' COLLATE latin1_swedish_ci THEN 2
+  END;
+
+SELECT 
+CASE _latin1'a' COLLATE latin1_general_ci  WHEN _latin1'A' THEN '1' ELSE 2 END,
+CASE _latin1'a' COLLATE latin1_bin         WHEN _latin1'A' THEN '1' ELSE 2 END,
+CASE _latin1'a' WHEN _latin1'A' COLLATE latin1_swedish_ci THEN '1' ELSE 2 END,
+CASE _latin1'a' WHEN _latin1'A' COLLATE latin1_bin        THEN '1' ELSE 2 END
+;
+
 #
 # COALESCE is a CASE abbrevation:
 #
@@ -52,7 +90,6 @@ drop table t1;
 #
 # Check COALESCE argument types aggregation
 
-SET NAMES latin1;
 --error 1265
 CREATE TABLE t1 SELECT COALESCE(_latin1'a',_latin2'a');
 --error 1265

sql/item_cmpfunc.cc

@@ -892,7 +892,7 @@ Item *Item_func_case::find_item(String *str)
       }
       if ((tmp=args[i]->val_str(str)))		// If not null
       {
-	if (sortcmp(tmp,first_expr_str,&my_charset_bin)==0)
+	if (sortcmp(tmp,first_expr_str,cmp_collation.collation)==0)
 	  return args[i+1];
       }
       break;
@@ -1027,7 +1027,7 @@ void Item_func_case::fix_length_and_dec()
   {
     agg[0]= args[first_expr_num];
     for (nagg= 0; nagg < ncases/2 ; nagg++)
-      agg[nagg+1]= args[nagg];
+      agg[nagg+1]= args[nagg*2];
     nagg++;
     agg_cmp_type(&cmp_type, agg, nagg);
     if ((cmp_type == STRING_RESULT) &&
@@ -1040,7 +1040,6 @@ void Item_func_case::fix_length_and_dec()
   
   max_length=0;
   decimals=0;
-  cached_result_type = args[1]->result_type();
   for (uint i=0 ; i < ncases ; i+=2)
   {
     set_if_bigger(max_length,args[i+1]->max_length);