[英]Simple MySQL WHERE query not using Index
Quick Answer: Query condition needs to be same type as column to use index. 快速解答:查询条件需要与使用索引的列相同。 I was trying to search a CHAR column with a numeric condition.
我试图用数字条件搜索CHAR列。
I have a table with 15 million rows. 我有一张1500万行的表。 I have a column called 'ticket' that can occur multiple times but it wouldn't occur very many times .
我有一个名为'ticket'的列可以多次出现,但不会发生很多次。 .
。 .
。 probably less than 10. I have created an index on this column but the explain command says that when I am using a simple 'WHERE ticket =' query that it is not using the index.
可能少于10.我在这个列上创建了一个索引,但是explain命令说当我使用一个简单的'WHERE ticket ='查询时它没有使用索引。 Obviously this confuses me as I am asking a question here.
显然这让我感到困惑,因为我在这里问一个问题。
CREATE TABLE company1.rTable (
`aDate` date DEFAULT NULL,
`fromD` date DEFAULT NULL,
`pNo` int(10) DEFAULT NULL,
`ticket` char(11) DEFAULT NULL,
`r` int(11) unsigned NOT NULL DEFAULT '0',
`line` tinyint(3) unsigned DEFAULT NULL,
`nNum` char(11) NOT NULL,
`pKey` char(7) DEFAULT NULL,
`modNum` char(4) DEFAULT NULL,
`dnum` smallint(5) unsigned NOT NULL,
`rdNum` smallint(5) unsigned DEFAULT NULL,
`pType` int(10) DEFAULT NULL,
`lNum` decimal(9,2) DEFAULT NULL,
`lineAmount` decimal(9,2) DEFAULT NULL,
`amount` decimal(9,2) DEFAULT NULL,
`amount1` decimal(9,2) DEFAULT NULL,
`amount2` decimal(9,2) DEFAULT NULL,
`amount3` decimal(9,2) DEFAULT NULL,
`amount4` decimal(9,2) DEFAULT NULL,
`amount5` decimal(9,2) DEFAULT NULL,
`amount6` decimal(9,2) DEFAULT NULL,
`amount7` decimal(9,2) DEFAULT NULL,
`amount8` decimal(9,2) DEFAULT NULL,
`amount9` decimal(9,2) DEFAULT NULL,
`amount10` decimal(9,2) DEFAULT NULL,
`tType` tinyint(4) DEFAULT NULL,
`lineB` decimal(9,2) DEFAULT NULL,
`lineD` char(1) DEFAULT NULL,
`lineP` decimal(9,2) DEFAULT NULL,
`lineI` decimal(9,2) DEFAULT NULL,
`lineC` decimal(9,2) DEFAULT NULL,
`lineW` decimal(9,2) DEFAULT NULL,
`lineR` decimal(9,2) DEFAULT NULL,
`lineM` decimal(9,2) DEFAULT NULL,
KEY `rADate` (`aDate`),
KEY `rTType` (`tType`),
KEY `rTicket` (`ticket`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1$$
My query: 我的查询:
SELECT *
FROM company1.rTable
WHERE ticket = 3478421;
Maybe there is a way to change the query to use the index? 也许有办法改变查询使用索引? I tried things like 'AND ticket > .
我试过像'AND ticket>这样的东西。 .
。 .'
“。 as a guess but that didn't help.
作为猜测,但这没有帮助。
ticket
是一个char列,您正在使用数字条件(3478421)。
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