Oh,
If any char fields add to index key ,then the >=' ' gets wrong .
ordno, qty ,mem
1
3
5
aaa 18
bbbbb 20
1. CREATE TABLE `t1` (
`mid` int(11) NOT NULL,
`qty` decimal(12,2) NOT NULL DEFAULT '0.00',
`ordno` char(8) NOT NULL DEFAULT '',
`mem` char(1) DEFAULT '',
PRIMARY KEY (`mid`),
KEY `key03` (`ordno`))
select * from t1 where ordno>=' '
gets wrong result 2 rows
2CREATE TABLE `t1` (
`mid` int(11) NOT NULL,
`qty` decimal(12,2) NOT NULL DEFAULT '0.00',
`ordno` char(8) NOT NULL DEFAULT '',
`mem` char(1) DEFAULT '',
PRIMARY KEY (`mid`))
select * from t1 where ordno>=' '
gets OK 5 rows
3.CREATE TABLE `t1` (
`mid` int(11) NOT NULL,
`qty` decimal(12,2) NOT NULL DEFAULT '0.00',
`ordno` char(8) NOT NULL DEFAULT '',
`mem` char(1) DEFAULT '',
PRIMARY KEY (`mid`),
KEY `key03` (`mem`))
select * from t1 where mem>=' '
0 rows wrong
4.CREATE TABLE `t1` (
`mid` int(11) NOT NULL,
`qty` decimal(12,2) NOT NULL DEFAULT '0.00',
`ordno` char(8) NOT NULL DEFAULT '',
`mem` char(1) DEFAULT '',
PRIMARY KEY (`mid`))
select * from t1 where mem>=' '
5 rows OK
Regards!
Shuming wang
