Question

我的表包含Databasename，tablename，columnname，query等列。但在查询列SELECT COUNT(MachineName) AS Cnt FROM Keys WHERE MachineName<>NULL中如何在表中使用此查询列执行（我需要执行查询列的剩余3列）可以任何人帮助我。

Answer 1

哦，我误会了。您是否正在搜索在查询列中执行查询的查询，并使用数据库中的值替换其中的某些值，如下例所示：

if object_ID('tempdb..Test') is null
begin
    create table tempdb..Test (
    dbname nvarchar(512),
    tblname nvarchar(512),
    columnename nvarchar(512),
    query nvarchar(MAX)
    )


    --  delete from tempdb..Test
    insert into tempdb..Test (dbname, tblname, columnename, query)
    values ('master','sysobjects','id','select count([col]) from [db]..[tbl] where [col] is not null') 

    insert into tempdb..Test (dbname, tblname, columnename, query)
    values ('master','syscolumns','id','select count([col]) from [db]..[tbl] where [col] is not null') 
end


declare @db nvarchar(512)
declare @tbl nvarchar(512)
declare @col nvarchar(512)
declare @qry nvarchar(512)
declare @cmd nvarchar(512)

declare cur_test cursor 
    for select dbname, tblname, columnename, query
    from tempdb..Test
open cur_test

FETCH NEXT FROM cur_test   
INTO @db, @tbl, @col, @qry

WHILE @@FETCH_STATUS = 0  
BEGIN  
    set @cmd = replace(replace(replace(@qry,'[db]', quotename(@db)), '[tbl]', quotename(@tbl)),'[col]', @col)
    exec sp_executesql @cmd


    FETCH NEXT FROM cur_test   
    INTO @db, @tbl, @col, @qry
END

close cur_test
deallocate cur_test

Answer 2

使用＆＃34; is＆＃34;与null进行比较。或＆＃34;不是＆＃34;操作

SELECT COUNT(MachineName) AS Cnt FROM Keys WHERE MachineName is not NULL

或者如果您想要列MachineName具有值的条目，请使用

SELECT COUNT(MachineName) AS Cnt FROM Keys WHERE MachineName is NULL

Answer 3

您搜索的内容如下：

select 'select count(*) from ' + QUOTENAME(so.name) + ' where ' + (SELECT QUOTENAME(Name) + ' is null and ' 
           FROM syscolumns sc
           where sc.id= so.id
            FOR XML PATH('') ) + '1=1' 
from sysobjects so 
where so.xtype='U'
order by so.id

在表中为每个数据库查找具有空值的列

3 个答案: