[MDEV-9302] Different field types for equivalent NULLIF and IF vs CASE with AVG(int_field) and 0e0 arguments Created: 2015-12-18  Updated: 2015-12-18  Resolved: 2015-12-18

Status: Closed
Project: MariaDB Server
Component/s: OTHER
Affects Version/s: 10.0, 10.1
Fix Version/s: 10.0.23

Type: Bug Priority: Major
Reporter: Alexander Barkov Assignee: Alexander Barkov
Resolution: Not a Bug Votes: 0
Labels: None


 Description   

This script:

DROP TABLE IF EXISTS t1,t2;
 
CREATE TABLE t1 (c1 INT DEFAULT NULL);
 
INSERT INTO t1 (c1) VALUES (1),(2),(3),(4);
 
CREATE TABLE t2
 
SELECT
 
  NULLIF(AVG(c1),0e0) AS c1,
 
  IF(AVG(c1)=0e0,NULL,AVG(c1)) AS c2,
 
  CASE WHEN AVG(c1)=0e0 THEN 0e0 ELSE AVG(c1) END AS c3
 
FROM t1;
 
SHOW CREATE TABLE t2;

returns

+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------+
 
| Table | Create Table                                                                                                                                                |
 
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------+
 
| t2    | CREATE TABLE `t2` (
 
  `c1` decimal(14,4) DEFAULT NULL,
 
  `c2` decimal(14,4) DEFAULT NULL,
 
  `c3` double DEFAULT NULL
 
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
 
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------+

All three columns should be of the same data type.

 Comments   
Comment by Alexander Barkov [ 2015-12-18 ]

Oops. There was a mistake in the script.
The correct script is:

DROP TABLE IF EXISTS t1,t2;
 
CREATE TABLE t1 (c1 INT DEFAULT NULL);
 
INSERT INTO t1 (c1) VALUES (1),(2),(3),(4);
 
CREATE TABLE t2
 
SELECT
 
  NULLIF(AVG(c1),0e0) AS c1,
 
  IF(AVG(c1)=0e0,NULL,AVG(c1)) AS c2,
 
  CASE WHEN AVG(c1)=0e0 THEN NULL ELSE AVG(c1) END AS c3
 
FROM t1;
 
SHOW CREATE TABLE t2;

and it does return an expected result.

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