Question

select t.table_name from information_schema.tables t
left join information_schema.columns c
on c.table_name = t.table_name
and c.table_schema = t.table_schema
where t.table_schema = 'test'
and count(c.column_name) = max(count(c.column_name))

我正在尝试从数据库“test”中选择具有最高列数的表。但是，我无法做到这一点。我也尝试选择count（c.column_name），但不是返回每个表的列数，而是返回最大列数。

如何选择列数最多的表？

Answer 1

尝试按表名分组。类似的东西：

SELECT TABLE_NAME, COUNT(*) as c
FROM INFORMATION_SCHEMA.COLUMNS
GROUP BY TABLE_NAME
ORDER BY c desc
LIMIT 1;

Fiddle

Answer 2

试试这个

select table_name, col_count
from
(
    select t.table_name, count(c.column_name) as col_count
    from information_schema.tables t
    left join information_schema.columns c
    on c.table_name = t.table_name
    and c.table_schema = t.table_schema
    where t.table_schema = 'test'
    group by t.table_name
) r
order by col_count desc

Answer 3

有点重复Mike的答案，但我还要添加数据库名称：

SELECT TABLE_SCHEMA, TABLE_NAME, COUNT(TABLE_NAME) AS C 
FROM INFORMATION_SCHEMA.COLUMNS 
GROUP BY TABLE_SCHEMA, TABLE_NAME
ORDER BY C DESC
LIMIT 0, 1

MySQL选择列数最多的表？

3 个答案: