一个表有3列,5行,那么一共有15个值,现在要计算整个表中所有值在表中出现的次数,不过这里表的列数是不确定的,上面的例子是3列,实际上也有可能是5列、20列,所以解决问题的步骤是这样的:
1、必须知道有多少列,然后构造动态语句,把这些列合并到一列中。
2、然后去重计算出所有的可能值。
3、最后计算每个值在表中出现了多少次。
if(OBJECT_ID('dbo.wc') is not null) drop table dbo.wc go create table wc ( a nvarchar(100), b nvarchar(100), c nvarchar(100) ) insert into wc values('1','2','3'), ('a','f','d'), ('2','b','c'), (null,'c','w'), ('3','d',null) declare @temp table (cn nvarchar(100)); declare @i int = 1; declare @v varchar(max)=''; declare @column varchar(100)=''; while @i <= ( select count(*) from sys.tables t inner join sys.columns c on t.object_id =c.object_id where t.name = 'wc' ) begin select @column = c.name from sys.tables t inner join sys.columns c on t.object_id =c.object_id where t.name = 'wc' and c.column_id = @i set @i = @i + 1 set @v = @v + ' select '+ @column + ' from wc union all' end select @v = LEFT(@v,len(@v)-LEN('union all')) --select @v insert into @temp exec (@v) ;with a as ( select cn from @temp where cn is not null group by cn ) select a.cn, COUNT(t.cn) from a inner join @temp t on a.cn = t.cn group by a.cn