Most recent datetime column and count for each table - sql

Question

I have a DB that has 1000+ tables. 100 of those tables are prefixed with a three letters (let's say 'ABC') Only half of those prefixed tables have MODIFIEDDATETIME column.
I'm trying to do a simple select query to get all the last updated MODIFIEDDATETIME stamp for each Table that actually has a MODIFIEDDATETIME on that table and also begins with the three letter prefix.
I've tried using this function but it doesn't seem to be getting me there. Thoughts?
sp_msforeachtable '
select ''?'', modifieddatetime, count(*)
from ?
where ? like ''%ABC%''
group by modifieddatetime
order by modifieddatetime desc
'

Answer 1

Borrowing from another answer earlier today:
For one, I recommend staying away from undocumented and unsupported
procedures like sp_MSForEachTable. They can be changed or even
removed from SQL Server at any time, and this specific procedure may
have the same symptoms reported by many against sp_MSForEachDb. (See
some background here and here.)
...but also see sp_ineachdb.
Here is how I would do it - most importantly, pull the row count from the metadata which - while not 100% accurate to the millisecond is usually close enough - will not bog down your system performing a scan of every single table:
DECLARE #sql NVARCHAR(MAX);
SELECT #sql = N'';
CREATE TABLE #x
(
[table] NVARCHAR(255),
updated DATETIME,
[rowcount] BIGINT
);
SELECT #sql = #sql + N'INSERT #x SELECT '''
+ QUOTENAME(OBJECT_SCHEMA_NAME([object_id]))
+ '.' + QUOTENAME(OBJECT_NAME([object_id])) + ''',
MAX(MODIFIEDDATETIME), (SELECT SUM(rows) FROM sys.partitions
WHERE [object_id] = ' + CONVERT(VARCHAR(12), [object_id])
+ ') FROM ' + QUOTENAME(OBJECT_SCHEMA_NAME([object_id]))
+ '.' + QUOTENAME(OBJECT_NAME([object_id])) + ';'
FROM sys.columns
WHERE UPPER(name) = 'MODIFIEDDATETIME'
AND UPPER(OBJECT_NAME([object_id])) LIKE 'ABC%';
EXEC sp_executesql #sql;
SELECT [table],updated,[rowcount] FROM #x;
DROP TABLE #x;
That said, I don't know if using MAX(MODIFIEDDATETIME) is appropriate for knowing when a table was touched last. What if a transaction failed? What if the last operation was a delete?

Answer 2

You could do it with dynamic SQL, but this will probably not be very efficient on 1000 tables!
DECLARE #SQL NVARCHAR(MAX) = ''
SELECT #SQL = #SQL + ' UNION SELECT COUNT(' + QUOTENAME(Column_Name) + ') [Rows], MAX(' + QUOTENAME(Column_Name) + ') [MaxModifiedDate], ''' + QUOTENAME(Table_Schema) + '.' + QUOTENAME(Table_Name) + ''' [TableName] FROM ' + QUOTENAME(Table_Schema) + '.' + QUOTENAME(Table_Name)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE Column_Name = 'ModifiedDateTime'
AND Table_Name LIKE 'ABC%'
SET #SQL = 'SELECT MaxModifiedDate, TableName, Rows FROM (' + STUFF(#SQL, 1, 7, '') + ') t ORDER BY MaxModifiedDate DESC'
print #sql
EXEC SP_EXECUTESQL #SQL
It basically builds a query like
SELECT MaxModifiedDate, TableName, Rows
FROM ( SELECT 'Table1' [TableName], MAX(ModifiedDate) [MaxModifedDate], COUNT(ModifiedDate) [Rows]
FROM Table1
UNION
SELECT 'Table2' [TableName], MAX(ModifiedDate) [MaxModifedDate], COUNT(ModifiedDate) [Rows]
FROM Table2
UNION
SELECT 'Table3' [TableName], MAX(ModifiedDate) [MaxModifedDate], COUNT(ModifiedDate) [Rows]
FROM Table3
UNION
...
) c
ORDER BY MaxModifiedDate DESC