bk commit into 4.0 tree (acurtis:1.2091) BUG#9547

[antony]

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ChangeSet
  1.2091 05/04/22 09:04:26 acurtis@stripped +3 -0
  Bug#9547 - CASE statement gives incorrect result
    Return type of CASE should match 1st return type.
  Complete Item_func_case::print()

  sql/item_cmpfunc.cc
    1.65 05/04/22 09:04:14 acurtis@stripped +48 -4
    Bug#9547
      Return type of CASE should match 1st return type.
    Complete Item_func_case::print()

  mysql-test/t/case.test
    1.8 05/04/22 09:04:14 acurtis@stripped +11 -0
    Bug#9547
      Test for bug

  mysql-test/r/case.result
    1.10 05/04/22 09:04:14 acurtis@stripped +11 -2
    Bug#9547
      Test for bug
      + fix existing tests which exhibited bug

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	acurtis
# Host:	xiphis.org
# Root:	/.amd_mnt/bk.anubis/host/work-acurtis/bug6616

--- 1.64/sql/item_cmpfunc.cc	2004-11-26 00:31:20 +00:00
+++ 1.65/sql/item_cmpfunc.cc	2005-04-22 09:04:14 +01:00
@@ -751,8 +751,33 @@
     return 0;
   }
   null_value= 0;
-  if (!(res=item->val_str(str)))
-    null_value= 1;
+  switch (cached_result_type)
+  {
+  case STRING_RESULT:
+    if (!(res=item->val_str(str)))
+      null_value= 1;
+    break;
+  case INT_RESULT:
+    str->set(item->val_int());
+    if (!item->null_value)
+      res= str;
+    else
+    {
+      null_value= 1;
+      res= 0;
+    }
+    break;
+  case REAL_RESULT:
+    str->set(item->val(), item->decimals);
+    if (!item->null_value)
+      res= str;
+    else
+    {
+      null_value= 1;
+      res= 0;
+    }
+    break;
+  }
   return res;
 }
 
@@ -876,12 +901,31 @@
   }
 }
 
-/* TODO:  Fix this so that it prints the whole CASE expression */
 
 void Item_func_case::print(String *str)
 {
-  str->append("case ");				// Not yet complete
+  if (first_expr)
+  {
+    str->append("case ");
+    first_expr->print(str);
+  }
+  else
+    str->append("case");
+  for (uint i=0 ; i < arg_count ; i+=2)
+  {
+    str->append(" when ");
+    args[i]->print(str);
+    str->append(" then ");
+    args[i+1]->print(str);
+  }
+  if (else_expr)
+  {
+    str->append(" else ");
+    else_expr->print(str);
+  }
+  str->append(" end");
 }
+
 
 /*
   Coalesce - return first not NULL argument.

--- 1.9/mysql-test/r/case.result	2002-12-26 13:55:21 +00:00
+++ 1.10/mysql-test/r/case.result	2005-04-22 09:04:14 +01:00
@@ -10,10 +10,10 @@
 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
-ok
+0
 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
-ok
+0
 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
@@ -70,4 +70,13 @@
 orange
 yellow
 green
+drop table t1;
+create table t1 (a int not null, b varchar(4) not null);
+insert into t1 values (1,'uno'), (2,'dos'), (3,'tres');
+select sql_no_cache a, case b when 'uno' then 1 when 'dos' then 2 else 'tres' end c from t1 where a=3;
+a	c
+3	0
+select sql_buffer_result sql_no_cache a, case b when 'uno' then 1 when 'dos' then 2 else 'tres' end c from t1 where a=3;
+a	c
+3	0
 drop table t1;

--- 1.7/mysql-test/t/case.test	2002-12-26 13:55:21 +00:00
+++ 1.8/mysql-test/t/case.test	2005-04-22 09:04:14 +01:00
@@ -39,3 +39,14 @@
 insert into t1 values (1,1,'orange'),(1,2,'large'),(2,1,'yellow'),(2,2,'medium'),(3,1,'green'),(3,2,'small');
 select max(case col when 1 then val else null end) as color from t1 group by row;
 drop table t1;
+
+#
+# Bug#9547: CASE statement gives incorrect result
+# Result type should always follow type of 1st result otherwise results
+# end up different if the resultset is buffered
+#
+create table t1 (a int not null, b varchar(4) not null);
+insert into t1 values (1,'uno'), (2,'dos'), (3,'tres');
+select sql_no_cache a, case b when 'uno' then 1 when 'dos' then 2 else 'tres' end c from t1 where a=3;
+select sql_buffer_result sql_no_cache a, case b when 'uno' then 1 when 'dos' then 2 else 'tres' end c from t1 where a=3;
+drop table t1;