How can I check the maximum value from a set of tables in SQL Server (if possible)? - sql

Question

We have a set of databases (80 in total). Every single one has a table called tblProfessions. The tables are not standardized. For example:
EDIT: all the databases are on the same server.
The DB1.dbo.tblProfessions is like:
intProfessionCode
strProfessionDescription
1
lawyer
2
dentist
...
...
30
doctor
And the DB72.dbo.tblProfessions is as follows:
intProfessionCode
strProfessionDescription
1
designer
2
butcher
...
...
80
chef
Suppose I ran a script from DBO1 to DBO72, and I found that the biggest table has 80 entries (in this case the DBO72 is the biggest one).
By my limited knowledge, all I know is to run the below script database by database, and write it down in a spreadsheet manually:
SELECT MAX(intProfessionCode) FROM [DB].dbo.tblProfessions;
Is there a script to run and loop through all the tblProfessions and get the one with the most entries? All I want is the biggest number found.
Thanks in advance.

Answer 1

You should be able to do something like this:
WITH dat
AS
(
SELECT 'db1' AS database_name, MAX(intProfessionCode) AS max_intProfessionCode
FROM DB1.dbo.tblProfessions
UNION ALL
...
UNION ALL
SELECT 'db72' AS database_name, MAX(intProfessionCode) AS max_intProfessionCode
FROM DB72.dbo.tblProfessions
)
SELECT dat.db, dat.max_intProfessionCode
FROM dat
INNER JOIN (SELECT MAX(max_intProfessionCode) AS max_intProfessionCode_overall
FROM dat) y
ON dat.max_intProfessionCode = y.max_intProfessionCode_overall
For situations like this, I usually query the catalog to write the above script rather than typing it out:
WITH
dat AS
(
SELECT STRING_AGG('SELECT ''' + QUOTENAME(s.name) + ''' AS db,
MAX(intProfessionCode) AS max_intProfessionCode
FROM ' + QUOTENAME(s.name) + '.' + QUOTENAME('dbo') + '.' + QUOTENAME('tblProfessions') + '
UNION ALL',' ') AS s
FROM sys.databases s
WHERE s.name LIKE 'DB%' --EDIT APPROPRIATELY
)
SELECT 'WITH dat
AS
(' + SUBSTRING(s,1,LEN(s) - LEN(' UNION ALL')) + ')
SELECT dat.db, dat.max_intProfessionCode
FROM dat
INNER JOIN (SELECT MAX(max_intProfessionCode) AS max_intProfessionCode_overall
FROM dat) y
ON dat.max_intProfessionCode = y.max_intProfessionCode_overall' AS scrpt
FROM dat;
Make sure the above is only returning data for the appropriate databases by editing the WHERE clause in the CTE, then copy the output, paste elsewhere and run it to get your results.