How to drop all tables in PostgreSQL?
Recently, One of the SQL Server users asked me this question for PostgreSQL.

Because in the SQL Server we can do this kind of bulk DDL operations using sp_MSforeachtable.

SQL Server: Use sp_MSforeachtable to apply a T-SQL command to every table of current Database

In the PostgreSQL, no such functionality is available. But I am sharing two options for dropping all tables of schema or database of PostgreSQL.

If you want to drop all tables of a schema, simply drop the schema.

DROP SCHEMA schema_name CASCADE;

Use pg_tables and prepare DROP TABLE script:
In the below script, you can modify the table/schema filter. Once you execute the below script, you can get a result of generated DROP SCRIPT which you can execute for dropping tables.

select 'drop table if exists "' || tablename || '" cascade;' 
from pg_tables
where schemaname = 'public';

In the previous post, I shared basic about SQL Server 2016 System-versioned temporal tables and how you can create it.

In the previous post, I created a tbl_Studetns table and now for testing, I am going to drop it here.

DROP TABLE tbl_Students
GO

But unfortunately, I got the below error.

Msg 13552, Level 16, State 1, Line 1
Drop table operation failed on table 'RND.dbo.tbl_Students' because it is not supported operation on system-versioned temporal tables.

The reason is, it is a system-versioned table and its dependent object is tbl_StudentsHistory table.

The solution is to disable system-versioned on that table by executing following statement.

ALTER TABLE dbo.tbl_Students SET (SYSTEM_VERSIONING = OFF)

Now, you can drop the tbl_Students table.

Please note:
We disabled the System-versioned so it will not drop a tbl_StudentsHistory table. If you want to tbl_StudentsHistory, you can use drop command to drop it.

DROP TABLE tbl_StudentsHistory
GO

In this post, I am sharing a script for dropping a table from all databases of SQL Server.

We are creating different versions of the database in our environment. Recently, I found some test/temp tables which are replicated in all versions databases.

In this case, you can use below script and drop those tables from all the databases. As per your requirement, you can add more option in a dynamic query.

Use sp_MSforeachdb, and execute a command in all databases:

exec sp_MSforeachdb
'use [?]
drop table table_name'

SQL Server: Who dropped a Table and Which Table has been dropped

SQL Server: Who dropped a table, find out from Transaction Log

How to log the DROP TABLE Statement in the log file of PostgreSQL?

Above is a common question/suggestion by the PostgreSQL DBA. We should log all the type of statements like DDL, DML. But DDL is most important than DML logging.

For logging the DDL statement into log files, we should change the following parameters in the postgresql.conf file.

log_statement=’ddl’
log_line_prefix = ‘%t %c %u ‘ (time, sessionid, user)
logging_collector = ON

For example:
I dropped a tbl_student table. Now, I can see below the line in my log file.

2017-12-08 16:23:12 CET LOG:  statement: DROP TABLE tbl_student;

In this post, I am sharing few steps to find out the transactions history for drop commands which executed in SQL Server.

There are many features for auditing and check the logging in SQL Server, but you can also directly read the transaction log and can get the necessary details.

Please check the below full demonstration of this:

Create a sample database and use it:

CREATE DATABASE Drop_Test
GO
USE Drop_Test
GO

CREATE TABLE tbl_Test (ID INT)
GO

SELECT OBJECT_ID ('tbl_Test')
GO

--tbl_Test object id: 581577110

DROP TABLE tbl_Test
GO

SELECT [Transaction Id], [Begin Time], SUSER_SNAME ([Transaction SID]) AS [User]
FROM fn_dblog (NULL, NULL)
WHERE [Transaction Name] = 'DROPOBJ'
GO

-- The Result:
/*
Transaction Id Begin Time User
-------------- ------------------------ ---------
0000:00000335 2017/04/25 17:53:41:187 Anvesh
*/

SELECT [Transaction Id], [Begin Time], SUSER_SNAME ([Transaction SID]) AS [User]
FROM fn_dblog (NULL, NULL)
WHERE [Transaction Name] = 'DROPOBJ'
GO

-- The Result:
/*
Transaction Id Begin Time User
-------------- ------------------------ ---------
0000:00000335 2017/04/25 17:53:41:187 Anvesh
*/

SQL Server provides different types of database auditing option like: CDC, Database Audit.
Recently, I have shared one article about, change your database DDL changes using Encrypted DDL triggers.

SQL Server: Encrypted DDL Trigger to Track all Database Changes

Database Administrators are responsible for database security and Periodically, They have to track all the database related changes and make sure that everything is working fine.

But still sometimes, I used to track database changes from the SQL Server log files using fn_dblog().
I am sharing one way to find a person who dropped a table and also can get the name of that dropped table without enabling any auditing option of SQL Server.

Script to find the log of dropped objects:

Using this script, you can find a list of dropped tables and login name information, but you cannot get table name directly.
You can find the transaction id for each record and using this transaction ID, you can find the table name.

SELECT 
	[Transaction Id]
	,[Begin Time]
	,SUSER_SNAME ([Transaction SID]) AS [LoginName] 
FROM fn_dblog (NULL, NULL)  
WHERE [Transaction Name] = N'DROPOBJ';

Find Table name using TransactionID:

SELECT TOP 1 
	[Lock Information] 
FROM fn_dblog (NULL, NULL)  
WHERE [Transaction Id] = '0000:0015d6b3'  
AND [Lock Information] LIKE '%SCH_M OBJECT%';

The result:
To get the table name, you can copy the number and search into sys.objects table.

HoBt 0:ACQUIRE_LOCK_SCH_M OBJECT: 8:1015674666:0

Find your dropped table:
Please do not start to search your dropped table in your current database because Table already dropped.
You must restore the last backup of the database and you should search your dropped table in that database.

SELECT *FROM sys.objects 
WHERE Object_ID ='1015674666'