insert into ... select ... where ... join语法

insert into ... select ... where ... join这样的语法为什么会报错？
例如：

insert into T2(c1, c2, c3)
select
t1.c1,
t1.c2,
t1.c3
from T1 t1
where
t1.c2 = 'y'
left join T3 t3 on t1.c1 = t3.c1
left join T4 t4 on t1.c1 = t4.c1;

---

select
t1.c1,
t1.c2
from T1 t1
left join T3 t3 on t1.c1 = t3.c1
left join T4 t4 on t1.c1 = t4.c1
where t1.c2 = 'y';

RTFM

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楼主注意代码T2(c1, c2, c3)里面需要插入的是三个字段

补充：
在多表进行连接查询时，应先使用on生成临时表，然后使用where进行SQL数据过滤操作。

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字段数量不一致！！