mysql of searching where without any data by foreign key-CodePudding

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mysql of searching where without any data by foreign key

Time：08-31

i have a problem of searching data .

A table

A_id name  
1    apple 
2    orange
3     sexy

B table

B_id A_id comment 
1      1         abcde

how can i get the a_id were without any comment in b table

i want the sql return

a_id name 
2 orange 
3 sexy

CodePudding user response：

SQLs NOT EXISTS operator is for that purpose:

select a_id, name
from A as AT
where not exists 
     (select *
      from B as BT
      where BT.a_id=AT.a_id)