How to get Max Date Value of Date column in Multiple tables - sql

Question

For example I have 2 tables in Database.
Ex :
Table T :
declare #t table (name varchar(20),DOB date)
Insert into #t (name,DOB) values ('Mohan','2001-07-19')
Insert into #t (name,DOB) values ('Minu','1998-06-19')
Table : TT
declare #tt table (name varchar(20),DOB date)
Insert into #tt (name,DOB) values ('Raju','2010-07-19')
Insert into #tt (name,DOB) values ('Rani','2001-06-19')
Now I have a Query to get Table name and column names of multiple tables basing on Date type filter .
SELECT C.TABLE_SCHEMA, c.TABLE_NAME,c.COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS c
JOIN sys.objects o ON o.name = c.TABLE_NAME
WHERE o.type = 'U' AND C.DATA_TYPE = 'Datetime'
Output :
T_Schema T_name T_column
dbo T DOB
dbo TT DOB
But how can I get max Date of both tables like below output :
T_Schema T_name T_column Max_dt
dbo T DOB 2001-07-19
dbo TT DOB 2010-07-19
Suggest me the best way to achieve this.

Answer 1

Here is another option that doesn't use a cursor. I doubt it will be any better from a performance perspective because you still need a subquery for every row. But I really hate cursors. I also used the system tables instead of the information schema views as those can sometimes be a bit odd. https://sqlblog.org/2011/11/03/the-case-against-information_schema-views
declare #SQL nvarchar(max) = N''
select #SQL = #SQL +
N'select SCHEMA_NAME = ''' + QUOTENAME(s.name) + ''', TABLE_NAME = '''
+ QUOTENAME(o.name) + ''', COLUMN_NAME = '''
+ QUOTENAME(c.name) + ''', MaxDate = '
+ '(select MAX(' + QUOTENAME(c.name) + ') from ' + QUOTENAME(s.name) + '.' + QUOTENAME(o.name) + ') UNION ALL '
from sys.columns c
join sys.systypes st on st.type = c.system_type_id
join sys.objects o on o.object_id = c.object_id and o.type = 'U'
join sys.schemas s on s.schema_id = o.schema_id
where st.name = 'datetime'
order by s.name
, o.name
, c.name
set #SQL = left(#SQL, len(#SQL) - 10) --removes final UNION ALL
select #SQL
--uncomment below when you are satisfied the dynamic sql is correct
--exec sp_executesql #SQL

Answer 2

Here's some dynamic SQL that should do what you want, via a cursor.
I'd caution using this if you have a lot of tables, or run this in test first. Cursors are not great performs generally speaking. You can run this against a system database, like master, which would have fewer values to see how it works.
create table #MaxDate (tname varchar(256), cname varchar(256), mdate datetime)
declare cur cursor local fast_forward
for
SELECT C.TABLE_SCHEMA, c.TABLE_NAME,c.COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS c
JOIN sys.objects o ON o.name = c.TABLE_NAME
WHERE o.type = 'U' AND C.DATA_TYPE = 'Datetime'
declare #schema varchar(64), #table varchar(256), #column varchar(256)
declare #sql varchar(max)
open cur
fetch next from cur into #schema, #table, #column
while ##FETCH_STATUS = 0
begin
set #sql = 'select ''' + #table + '''' + ',''' + '' + #column + '''' + ',' + 'max(' + #column + ') from ' + #schema + '.' + #table
print #sql
insert into #MaxDate
exec (#sql)
fetch next from cur into #schema, #table, #column
end
close cur
deallocate cur
select * from #MaxDate
drop table #MaxDate

Answer 3

Here's an answer using a cursor, dynamic SQL and a temporary table:
DECLARE table_cursor CURSOR LOCAL FAST_FORWARD FOR
SELECT
C.TABLE_SCHEMA,
c.TABLE_NAME,
c.COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS c
JOIN sys.objects o
ON o.name = c.TABLE_NAME
WHERE o.type = 'U'
AND C.DATA_TYPE = 'Datetime'
DECLARE #schema SYSNAME
DECLARE #table SYSNAME
DECLARE #column SYSNAME
DECLARE #sql NVARCHAR(1000)
CREATE TABLE #Data (SchemaName SYSNAME, TableName SYSNAME, ColumnName SYSNAME, MaxDate DATETIME)
OPEN table_cursor
FETCH NEXT FROM table_cursor INTO #schema, #table, #column
WHILE ##FETCH_STATUS = 0
BEGIN
SET #sql = 'INSERT INTO #Data (SchemaName, TableName, ColumnName, MaxDate) SELECT '''+#schema+''', '''+#table+''', '''+#column+''', MAX(['+#column+']) FROM ['+#schema+'].['+#table+']'
EXEC sp_executesql #sql
FETCH NEXT FROM table_cursor INTO #schema, #table, #column
END
CLOSE table_cursor
DEALLOCATE table_cursor
SELECT * FROM #Data
DROP TABLE #Data

Answer 4

SQL to BUILD SQL for you
DECLARE #SQL as nvarchar(max) ='';
select #SQL = #SQL + 'SELECT ' + Column_Name + ' adate, ''' + Column_Name + ''' colname, ''' + Table_name + ''' tabname FROM ' + Table_name + ' UNION ' FROM INFORMATION_SCHEMA.COLUMNS where data_type like '%date%'
select #SQL = 'SELECT TOP 100 * FROM (' + LEFT(#SQL, LEN(#SQL) -6) + ') IQ WHERE IQ.adate IS NOT null ORDER BY IQ.adate DESC';
--cut n paste the sql below, see what it does for you
select #SQL
mark II - executes sql for you, and sorts out names with spaces in them
DECLARE #SQL as nvarchar(max) ='';
select #SQL = #SQL + 'SELECT [' + Column_Name + '] adate, ''' + Column_Name + ''' colname, ''' + Table_name + ''' tabname FROM [' + Table_name + '] UNION ' FROM INFORMATION_SCHEMA.COLUMNS where data_type like '%date%'
select #SQL = 'SELECT TOP 100 * FROM (' + LEFT(#SQL, LEN(#SQL) -6) + ') IQ WHERE IQ.adate IS NOT null ORDER BY IQ.adate DESC';
select #SQL;
EXEC sp_executesql #sql;