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## 这条查询耗时31s ProductID , ProductName 建立了索引
## EXPLAIN 里,使用了 ProductID 的索引
select * FROM products
where ProductName like '%宝%'
and ProductName like '%宝%'
and ProductName like '%爬%'
and ProductName like '%行%'
and ProductName like '%垫%'
and ProductName like '%可%'
and ProductName like '%机%'
and ProductName like '%洗%'
ORDER BY ProductID DESC
limit 0,20;
## 去掉Order By 耗时3s
## 没用到索引
select * FROM products
where ProductName like '%宝%'
and ProductName like '%宝%'
and ProductName like '%爬%'
and ProductName like '%行%'
and ProductName like '%垫%'
and ProductName like '%可%'
and ProductName like '%机%'
and ProductName like '%洗%'
limit 0,20;
## 使用主键ID Order By 耗时3s
## EXPLAIN 里,使用了 PRIMARY 的索引
select * FROM products
where ProductName like '%宝%'
and ProductName like '%宝%'
and ProductName like '%爬%'
and ProductName like '%行%'
and ProductName like '%垫%'
and ProductName like '%可%'
and ProductName like '%机%'
and ProductName like '%洗%'
ORDER BY ID
limit 0,20;