要仅检查表中是否已有Lion:
select count(*) from animals where name = 'Lion'
insert into animals (name)
select 'Lion'
where not exists
(
select * from animals where name = 'Lion'
)
select name from animals where name in ('Lion', 'Tiger', 'Jaguar')
对于每个已经存在的动物,这将最多返回3行。