Remove a ROW of NULL entries SQl Server - sql

Question

If I have a table which looks like this
Is there a way to remove all rows in a SQL tablw without knowing the column titles, if each item in that row is NULL?
Thanks!

Answer 1

Maybe there is another way but since you've tagged SqlCommand i would use ADO.NET. You can use dataReader.GetSchemaTable to retrieve column informations only:
// retrieve column names only
DataTable schema = null;
using (var con = new SqlConnection(Properties.Settings.Default.ConnectionString))
{
using (var schemaCommand = new SqlCommand("SELECT * FROM dbo.TableName", con))
{
con.Open();
using (var reader = schemaCommand.ExecuteReader(CommandBehavior.SchemaOnly))
{
schema = reader.GetSchemaTable();
}
}
}
// build sql with parameters dynamically
var columnQuery = schema.AsEnumerable()
.Select(r => string.Format("{0} IS NULL", r.Field<String>("ColumnName")));
string where = string.Join(" AND ", columnQuery);
string sql = string.Format("DELETE FROM dbo.TableName WHERE {0}", where);
// here you are
Of course you need two queries, one to select the columns and one to delete the null-rows. So the best way would be to know the columns in the first place.

Answer 2

Here's a snippet that should allow you to first SEE what your delete statements will look like, and then run it again when you're ready to actually perform the deletions:
begin
set nocount on
create table #temp_sql_text (sql_text varchar(max))
declare #table_name varchar(max)
declare c cursor for
select name from sys.tables order by name
open c
fetch next from c into #table_name
while ##fetch_status = 0
begin
insert into #temp_sql_text
select 'delete from ' + #table_name + ' where ' + replace(stuff(ColumnList, 1, 3, ''), '|||', ' is null and ') + ' is null'
from (
select '|||' + '[' + c.name + ']'
from sys.tables t inner join sys.columns c on c.object_id = t.object_id
where t.name = #table_name
order by c.column_id
for xml path('')
) o (ColumnList)
fetch next from c into #table_name
end
close c
deallocate c
declare #sql_text varchar(max)
declare c2 cursor for
select sql_text from #temp_sql_text
open c2
fetch next from c2 into #sql_text
while ##fetch_status = 0
begin
--Suggest just printing out the delete queries as a test before executing them!
print #sql_text
--Uncomment the next line to also execute the delete queries
--exec sp_executesql #sql_text
fetch next from c2 into #sql_text
end
close c2
deallocate c2
drop table #temp_sql_text
set nocount off
end

Answer 3

try this: I just tried on SQL server 2008 R2. I am not good with how to place the code in answer. please bare it.
declare #tempvar as nvarchar(max)
set #tempvar='X'
select #tempvar=#tempvar+COLUMN_NAME+' is NULL AND ' from
DatabaseName.INFORMATION_SCHEMA.COLUMNS where TABLE_NAME='Table_Name'
print #tempvar
Select #tempvar=CONCAT(#tempvar, 'X')
print #tempvar
Select #tempvar= REPLACE(#tempvar,'AND X','')
print #tempvar
Select #tempvar= REPLACE(#tempvar,'X',' ')
print #tempvar
declare #queryex as nvarchar(max)
set #queryex='select * from Table_Name where'+#tempvar
print #queryex
EXEC sp_executesql #queryex

Answer 4

If you know the number of columns in the table, you can do this:
delete from
tableToScrub
where
checksum(*) =
checksum(
cast(null as int),
cast(null as int)
-- Add one null to checksum per column
)
If you don't know the number of columns, you can do this:
with
nullset
as (
select
cast(null as int) as col1,
cast(null as int) as col2,
cast(null as int) as col3,
cast(null as int) as col4,
cast(null as int) as col5,
cast(null as int) as col6,
cast(null as int) as col7
-- add columns as necessary for your tables
)
,
nullchecksums
as (
select checksum(col1) as nullsum, 1 as columnCount from nullset union
select checksum(col1, col2), 2 from nullset union
select checksum(col1, col2, col3), 3 from nullset union
select checksum(col1, col2, col3, col4) , 4 from nullset union
select checksum(col1, col2, col3, col4, col5) , 5 from nullset union
select checksum(col1, col2, col3, col4, col5, col6) , 6 from nullset union
select checksum(col1, col2, col3, col4, col5, col6, col7) , 7 from nullset
-- add rows as necessary
)
delete from
tableToScrub
where
checksum(*) = (
select
nullsum
from
nullchecksums
where
columncount = (
select
count(1) as columnCount
from
sys.columns
where
object_id = object_id('SchemaName.TableToScrub')
)
)