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sql question?

sql question?# Database - 数据库

s*e2004-06-16 07:06

1 楼

There is a table with gene_ids (‘gid’) and clone_ids (‘cid’). Each gene
only resides on a single clone and each clone may contain multiple genes. How
do you find how many genes are on each and every clone? Please provide the
SQL.
My ans:
select count(gene_ids.gid)
from gene_ids inner join clone_ids on gene_ids.cid = clone_ids.cid
group by (clone_ids.cid)
or
select(count(gene_ids.gid)
from gene_ids, clone_ids
where gene_ids.cid = clone_ids.cid
group by (clone_ids.cid)
Are they correct?

n*f2004-06-16 07:06

2 楼

How many table you have? 2 or 1 ?
Could you please show the structre and data?
What the data looks like then?

gene
How

【在 s******e 的大作中提到】

: There is a table with gene_ids (‘gid’) and clone_ids (‘cid’). Each gene
: only resides on a single clone and each clone may contain multiple genes. How
: do you find how many genes are on each and every clone? Please provide the
: SQL.
: My ans:
: select count(gene_ids.gid)
: from gene_ids inner join clone_ids on gene_ids.cid = clone_ids.cid
: group by (clone_ids.cid)
: or
: select(count(gene_ids.gid)