Bug #27921 View ignores precision for CAST()

Item_decimal_typecast::print properly implemented

mysql-test/r/view.result

@@ -1789,7 +1789,7 @@ drop table t1;
 create view v1 as select cast(1 as decimal);
 select * from v1;
 cast(1 as decimal)
-1.00
+1
 drop view v1;
 create table t1(f1 int);
 create table t2(f2 int);
@@ -3354,4 +3354,17 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 NULL	UNION RESULT	<union1,2>	ALL	NULL	NULL	NULL	NULL	NULL	Using filesort
 DROP VIEW v1;
 DROP TABLE t1;
+CREATE VIEW v1 AS SELECT CAST( 1.23456789 AS DECIMAL( 7,5 ) ) AS col;
+SELECT * FROM v1;
+col
+1.23457
+DESCRIBE v1;
+Field	Type	Null	Key	Default	Extra
+col	decimal(7,5)	NO		0.00000	
+DROP VIEW v1;
+CREATE VIEW v1 AS SELECT CAST(1.23456789 AS DECIMAL(8,0)) AS col;
+SHOW CREATE VIEW v1;
+View	Create View
+v1	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select cast(1.23456789 as decimal(8,0)) AS `col`
+DROP VIEW v1;
 End of 5.0 tests.

mysql-test/t/view.test

@@ -3221,4 +3221,16 @@ EXPLAIN SELECT * FROM t1 UNION SELECT * FROM v1 ORDER BY a;
 DROP VIEW v1;
 DROP TABLE t1;
 
+#
+# Bug #27921 View ignores precision for CAST()
+#
+CREATE VIEW v1 AS SELECT CAST( 1.23456789 AS DECIMAL( 7,5 ) ) AS col;
+SELECT * FROM v1;
+DESCRIBE v1;
+DROP VIEW v1;
+
+CREATE VIEW v1 AS SELECT CAST(1.23456789 AS DECIMAL(8,0)) AS col;
+SHOW CREATE VIEW v1;
+DROP VIEW v1;
+
 --echo End of 5.0 tests.

sql/field.cc

@@ -8426,8 +8426,7 @@ bool create_field::init(THD *thd, char *fld_name, enum_field_types fld_type,
   case FIELD_TYPE_NULL:
     break;
   case FIELD_TYPE_NEWDECIMAL:
-    if (!fld_length && !decimals)
-      length= 10;
+    my_decimal_trim(&length, &decimals);
     if (length > DECIMAL_MAX_PRECISION)
     {
       my_error(ER_TOO_BIG_PRECISION, MYF(0), length, fld_name,

sql/item_create.cc

@@ -445,11 +445,13 @@ Item *create_load_file(Item* a)
 }
 
 
-Item *create_func_cast(Item *a, Cast_target cast_type, int len, int dec,
+Item *create_func_cast(Item *a, Cast_target cast_type,
+                       const char *c_len, const char *c_dec,
 		       CHARSET_INFO *cs)
 {
   Item *res;
-  int tmp_len;
+  ulong len;
+  uint dec;
   LINT_INIT(res);
 
   switch (cast_type) {
@@ -460,15 +462,18 @@ Item *create_func_cast(Item *a, Cast_target cast_type, int len, int dec,
   case ITEM_CAST_TIME:		res= new Item_time_typecast(a); break;
   case ITEM_CAST_DATETIME:	res= new Item_datetime_typecast(a); break;
   case ITEM_CAST_DECIMAL:
-    tmp_len= (len>0) ? len : 10;
-    if (tmp_len < dec)
+    len= c_len ? atoi(c_len) : 0;
+    dec= c_dec ? atoi(c_dec) : 0;
+    my_decimal_trim(&len, &dec);
+    if (len < dec)
     {
       my_error(ER_M_BIGGER_THAN_D, MYF(0), "");
       return 0;
     }
-    res= new Item_decimal_typecast(a, tmp_len, dec ? dec : 2);
+    res= new Item_decimal_typecast(a, len, dec);
     break;
   case ITEM_CAST_CHAR:
+    len= c_len ? atoi(c_len) : -1;
     res= new Item_char_typecast(a, len, cs ? cs : 
 				current_thd->variables.collation_connection);
     break;
@@ -476,6 +481,7 @@ Item *create_func_cast(Item *a, Cast_target cast_type, int len, int dec,
   return res;
 }
 
+
 Item *create_func_is_free_lock(Item* a)
 {
   current_thd->lex->uncacheable(UNCACHEABLE_SIDEEFFECT);

sql/item_create.h

@@ -27,7 +27,8 @@ Item *create_func_bit_length(Item* a);
 Item *create_func_coercibility(Item* a);
 Item *create_func_ceiling(Item* a);
 Item *create_func_char_length(Item* a);
-Item *create_func_cast(Item *a, Cast_target cast_type, int len, int dec,
+Item *create_func_cast(Item *a, Cast_target cast_type,
+                       const char *len, const char *dec,
                        CHARSET_INFO *cs);
 Item *create_func_connection_id(void);
 Item *create_func_conv(Item* a, Item *b, Item *c);

sql/item_func.cc

@@ -1059,9 +1059,26 @@ my_decimal *Item_decimal_typecast::val_decimal(my_decimal *dec)
 
 void Item_decimal_typecast::print(String *str)
 {
+  char len_buf[20*3 + 1];
+  char *end;
+  CHARSET_INFO *cs= str->charset();
+
+  uint precision= my_decimal_length_to_precision(max_length, decimals,
+                                                 unsigned_flag);
   str->append(STRING_WITH_LEN("cast("));
   args[0]->print(str);
-  str->append(STRING_WITH_LEN(" as decimal)"));
+  str->append(STRING_WITH_LEN(" as decimal("));
+
+  end=int10_to_str(precision, len_buf,10);
+  str->append(len_buf, (uint32) (end - len_buf));
+
+  str->append(',');
+
+  end=int10_to_str(decimals, len_buf,10);
+  str->append(len_buf, (uint32) (end - len_buf));
+
+  str->append(')');
+  str->append(')');
 }
 
 

sql/item_func.h

@@ -331,8 +331,8 @@ class Item_decimal_typecast :public Item_func
 public:
   Item_decimal_typecast(Item *a, int len, int dec) :Item_func(a)
   {
-    max_length= len + 2;
     decimals= dec;
+    max_length= my_decimal_precision_to_length(len, dec, unsigned_flag);
   }
   String *val_str(String *str);
   double val_real();

sql/my_decimal.h

@@ -387,5 +387,18 @@ int my_decimal_cmp(const my_decimal *a, const my_decimal *b)
   return decimal_cmp((decimal_t*) a, (decimal_t*) b);
 }
 
+
+inline
+void my_decimal_trim(ulong *precision, uint *scale)
+{
+  if (!(*precision) && !(*scale))
+  {
+    *precision= 10;
+    *scale= 0;
+    return;
+  }
+}
+
+
 #endif /*my_decimal_h*/
 

sql/sql_yacc.yy

@@ -4699,15 +4699,12 @@ simple_expr:
 	| ASCII_SYM '(' expr ')' { $$= new Item_func_ascii($3); }
 	| BINARY simple_expr %prec NEG
 	  {
-            $$= create_func_cast($2, ITEM_CAST_CHAR, -1, 0, &my_charset_bin);
+            $$= create_func_cast($2, ITEM_CAST_CHAR, NULL, NULL, &my_charset_bin);
 	  }
 	| CAST_SYM '(' expr AS cast_type ')'
 	  {
             LEX *lex= Lex;
-	    $$= create_func_cast($3, $5,
-                                 lex->length ? atoi(lex->length) : -1,
-                                 lex->dec ? atoi(lex->dec) : 0,
-                                 lex->charset);
+	    $$= create_func_cast($3, $5, lex->length, lex->dec, lex->charset);
             if (!$$)
               MYSQL_YYABORT;
 	  }
@@ -4715,10 +4712,7 @@ simple_expr:
 	  { $$= new Item_func_case(* $3, $2, $4 ); }
 	| CONVERT_SYM '(' expr ',' cast_type ')'
 	  {
-	    $$= create_func_cast($3, $5,
-				 Lex->length ? atoi(Lex->length) : -1,
-                                 Lex->dec ? atoi(Lex->dec) : 0,
-				 Lex->charset);
+	    $$= create_func_cast($3, $5, Lex->length, Lex->dec, Lex->charset);
             if (!$$)
               MYSQL_YYABORT;
 	  }