在表中为每个数据库查找具有空值的列[关闭]

Posted 2021-04-20

我有表格，如Databasename，tablename，columnname，query。但在查询列SELECT COUNT(MachineName) AS Cnt FROM Keys WHERE MachineName<>NULL。 如何使用表中的此查询列执行（我需要执行查询列的剩余3列）任何人都可以帮助我。

答案

哦，我误解了。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  

另一答案

使用“is”或“is not”运算符与null进行比较。

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

另一答案

你搜索这样的东西：

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