A表左连B表，但又要A表中a1字段的值仅包含B表中 b1字段的记录，如何写SQL语句啊

select * from a,b
where a.id=b.id(+) and instr(a1,b1)>0

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SQL code

select a.*
  from a left join b
    on a.a1 = b.b1
 where b1 is not null;

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SQL code

select * from a,b
where  a1 not in (select b1 from b where a.id=b.id(+))

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select a.*  from a left join b on a.a2 = b.b2 and a.a1<>b.b1