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Bug #6172: RAND(a) should only accept constant values as arguments

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RAND() must accept scalar expressions regardless of their kind.
 That includes both constant expressions and expressions that 
 depend on column values.
 When the expression is constant the random seed can be initialized
 at compile time.
 However when the expression is not constant the random seed must be
 initialized at each invocation (while it still can be allocated at
 compile time).
 Implemented the above rules by extending Item_func_rand::val_real()
 to initialize the random seed at the correct place.


mysql-test/r/func_math.result:
  Bug #6172: RAND(a) should only accept constant values as arguments
   - extened the test case
mysql-test/t/func_math.test:
  Bug #6172: RAND(a) should only accept constant values as arguments
   - extened the test case
sql/item_func.cc:
  Bug #6172: RAND(a) should only accept constant values as arguments
   - allow specifying non-const expressions as RAND() arguments
sql/item_func.h:
  Bug #6172: RAND(a) should only accept constant values as arguments
   - allow specifying non-const expressions as RAND() arguments
This commit is contained in:
unknown
2007-01-23 19:45:58 +02:00
parent 9af4bbc7b0
commit d74a7b9def
4 changed files with 78 additions and 29 deletions
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45
mysql-test/r/func_math.result
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@ -177,11 +177,46 @@ drop table t1;
select abs(-2) * -2;
abs(-2) * -2
-4
create table t1 (i int);
insert into t1 values (1);
select rand(i) from t1;
ERROR HY000: Incorrect arguments to RAND
drop table t1;
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(1),(1),(2);
SELECT CAST(RAND(2) * 1000 AS UNSIGNED), CAST(RAND(a) * 1000 AS UNSIGNED)
FROM t1;
CAST(RAND(2) * 1000 AS UNSIGNED) CAST(RAND(a) * 1000 AS UNSIGNED)
656 405
122 405
645 405
858 656
SELECT CAST(RAND(2) * 1000 AS UNSIGNED), CAST(RAND(a) * 1000 AS UNSIGNED)
FROM t1 WHERE a = 1;
CAST(RAND(2) * 1000 AS UNSIGNED) CAST(RAND(a) * 1000 AS UNSIGNED)
656 405
122 405
645 405
INSERT INTO t1 VALUES (3);
SELECT CAST(RAND(2) * 1000 AS UNSIGNED), CAST(RAND(a) * 1000 AS UNSIGNED)
FROM t1;
CAST(RAND(2) * 1000 AS UNSIGNED) CAST(RAND(a) * 1000 AS UNSIGNED)
656 405
122 405
645 405
858 656
354 906
SELECT CAST(RAND(2) * 1000 AS UNSIGNED), CAST(RAND(a) * 1000 AS UNSIGNED)
FROM t1 WHERE a = 1;
CAST(RAND(2) * 1000 AS UNSIGNED) CAST(RAND(a) * 1000 AS UNSIGNED)
656 405
122 405
645 405
PREPARE stmt FROM
"SELECT CAST(RAND(2) * 1000 AS UNSIGNED), CAST(RAND(?) * 1000 AS UNSIGNED)
FROM t1 WHERE a = 1";
set @var=2;
EXECUTE stmt USING @var;
CAST(RAND(2) * 1000 AS UNSIGNED) CAST(RAND(?) * 1000 AS UNSIGNED)
656 656
122 122
645 645
DROP TABLE t1;
create table t1 (a varchar(90), ts datetime not null, index (a)) engine=innodb default charset=utf8;
insert into t1 values ('http://www.foo.com/', now());
select a from t1 where a='http://www.foo.com/' order by abs(timediff(ts, 0));