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有个问题，我有一张 A表和B表，A表是主表，用于存放主要信息，B表是附加表，存放次要信息，请问我怎么把B表的其中一个字段 带上字段中的值复制到主表中？
UPDATE A INNER JOIN B ON A.id = B.id SET A.a = B.b;
A.id = B.id: the associated fields of the two tables; A.a: the field that receives the data from table B; B.b: the field that will be copied to table A.
First you need to add this field to table A, and then update the joint table Or you can create a view for them if you need a simple query
A relates to B, join table query
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A.id = B.id: the associated fields of the two tables;
A.a: the field that receives the data from table B;
B.b: the field that will be copied to table A.
First you need to add this field to table A, and then update the joint table
Or you can create a view for them if you need a simple query
A relates to B, join table query