[英]MySQL Select Query running very slow
我有一个有效的MySQL查询,但速度很慢。 我猜是由于加入的数量。
SELECT
order_header.order_head_id,
order_header.order_date,
order_header.status,
suppliers.supplier,
categories.category,
order_header.user,
order_header.sage_ref,
SUM(order_lines.total_price) AS price
FROM
order_header
LEFT JOIN
order_lines ON order_header.order_head_id = order_lines.order_head_id
LEFT JOIN
suppliers ON order_header.supplier_id = suppliers.supp_id
LEFT JOIN
categories ON order_header.category = categories.cat_id
WHERE
order_header.status LIKE '%'
AND order_header.order_head_id LIKE '%'
AND order_header.user LIKE '%'
GROUP BY order_header.order_head_id
ORDER BY order_head_id DESC
LIMIT 50;
显示创建表结果
CREATE TABLE `categories` (
`cat_id` int(11) NOT NULL AUTO_INCREMENT,
`category` varchar(45) DEFAULT NULL,
`status` varchar(45) DEFAULT NULL,
PRIMARY KEY (`cat_id`)
) ENGINE=InnoDB AUTO_INCREMENT=63 DEFAULT CHARSET=latin1
CREATE TABLE `order_header` (
`order_head_id` int(11) NOT NULL AUTO_INCREMENT,
`status` varchar(45) DEFAULT NULL,
`category` varchar(45) NOT NULL,
`order_date` date DEFAULT NULL,
`supplier_id` varchar(45) NOT NULL,
`user` varchar(45) DEFAULT NULL,
`sage_ref` varchar(45) DEFAULT NULL,
`query_notes` varchar(500) DEFAULT NULL,
PRIMARY KEY (`order_head_id`)
) ENGINE=InnoDB AUTO_INCREMENT=2249 DEFAULT CHARSET=latin1
CREATE TABLE `order_lines` (
`order_lines_id` int(11) NOT NULL AUTO_INCREMENT,
`order_head_id` int(11) DEFAULT NULL,
`qty` int(11) DEFAULT NULL,
`description` varchar(255) DEFAULT NULL,
`unit_price` decimal(65,2) DEFAULT NULL,
`total_price` decimal(65,2) DEFAULT NULL,
PRIMARY KEY (`order_lines_id`)
) ENGINE=InnoDB AUTO_INCREMENT=3981 DEFAULT CHARSET=latin1
CREATE TABLE `suppliers` (
`supp_id` int(11) NOT NULL AUTO_INCREMENT,
`supplier` varchar(255) DEFAULT NULL,
`status` varchar(225) DEFAULT NULL,
PRIMARY KEY (`supp_id`)
) ENGINE=InnoDB AUTO_INCREMENT=161 DEFAULT CHARSET=latin1
SQL版本5.6.30
我对MySQL的了解不是很好,并且想知道是否有人可以看到一种改进查询以使其运行更快的方法。
您的帮助将不胜感激。
非常感谢,
约翰
将第一个(左)联接包装到GROUP BY子查询中可能很有意义。 GROUP BY和LIMIT将限制在以下两个联接中使用的行数:
SELECT
x.order_head_id,
x.order_date,
x.status,
suppliers.supplier,
categories.category,
x.user,
x.sage_ref,
x.price
FROM (
SELECT
order_header.supplier_id,
order_header.category,
order_header.order_head_id,
order_header.order_date,
order_header.status,
order_header.user,
order_header.sage_ref,
SUM(order_lines.total_price) AS price
FROM order_header
LEFT JOIN order_lines ON order_header.order_head_id = order_lines.order_head_id
WHERE order_header.status LIKE '%'
AND order_header.order_head_id LIKE '%'
AND order_header.user LIKE '%'
GROUP BY order_header.order_head_id
ORDER BY order_head_id DESC
LIMIT 50
) x
LEFT JOIN suppliers ON x.supplier_id = suppliers.supp_id
LEFT JOIN categories ON x.category = categories.cat_id
ORDER BY order_head_id DESC
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