mysql在限制条件下筛选某列数据相同的值？

Question

有一个schema如下fish（name,species,tankid）
eat(species1，species2)其中eat表示鱼类之间相互捕食关系，species1是被捕食的鱼类tankid表示鱼缸id需要筛选出：与可以捕食他的鱼（species2）放在同一个鱼缸中（tankid相等）的鱼（species1）的名字求用sql语句说明

数据分析师 · Answer

Mysql filters the same values in a column of data under restricted conditions? -PHP Chinese website Q&A-Mysql filters the same values in a column of data under restricted conditions? -PHP Chinese website Q&A

Let’s take a look and learn.

迷茫 · Answer

SELECT a.*, b.name AS name1, c.name AS name2
FROM eat AS a 
LEFT JOIN fish AS b ON a.species1=b.species
LEFT JOIN fish AS c ON a.species2=c.species
WHERE b.tankid=c.tankid

mysql在限制条件下筛选某列数据相同的值？

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