oracle 如何获得数据库行中字符串的唯一长度的计数？
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How can an get count of the unique lengths of a string in database rows?
提问by johnny
I am using Oracle and I have a table with 1000 rows. There is a last name field and
我正在使用 Oracle 并且我有一个包含 1000 行的表。有一个姓氏字段和
I want to know the lengths of the name field but I don't want it for every row. I want a count of the various lengths.
我想知道 name 字段的长度，但我不希望每一行都有它。我想要各种长度的计数。
Example:
例子：
lastname:
姓：
smith
smith
Johnson
Johnson
Hymanson
Baggins
There are two smiths length of five. Four others, length of seven. I want my query to return
有两个史密斯长度为五。其他四个，长度为七。我希望我的查询返回
7
5
If there were 1,000 names I expect to get all kinds of lengths.
如果有 1,000 个名字，我希望得到各种长度。
I tried,
我试过，
Select count(*) as total, lastname from myNames group by total
It didn't know what total was. Grouping by lastname just groups on each individual name unless it's a different last name, which is as expected but not what I need.
它不知道总数是多少。按姓氏分组只是对每个单独的名字进行分组，除非它是不同的姓氏，这是预期的，但不是我需要的。
Can this be done in one SQL query?
这可以在一个 SQL 查询中完成吗？
回答by Joel Coehoorn
SELECT Length(lastname)
FROM MyTable
GROUP BY Length(lastname)
回答by Chris
select distinct(LENGTH(lastname)) from mynames;
回答by Goutham
Select count(*), Length(column_name) from table_name group by Length(column_name);
This will work for the different lengths in a single column.
这将适用于单个列中的不同长度。
