To answer this question, we need to understand the SQL300 error code in SQL.

Option A) DDL not allowed on this table definition - This option is correct because the SQL300 error code typically indicates that a Data Definition Language (DDL) statement is not allowed on the specified table definition. This error can occur when trying to alter or modify the structure of a table in a way that is not permitted.

Option B) Column with this name already exists - This option is incorrect. The SQL300 error code is not related to a column already existing. Instead, it is specifically related to DDL statements on table definitions.

Option C) View's WITH CHECK OPTION validation failed in UPDATE - This option is incorrect. The SQL300 error code is not related to the validation failure of a view's WITH CHECK OPTION in an UPDATE statement. It is specific to DDL statements on table definitions.

Option D) One or more matching rows is locked by another user - This option is incorrect. The SQL300 error code is not related to locked rows by another user. It is specific to DDL statements on table definitions.

Therefore, the correct answer is A) DDL not allowed on this table definition.

• Thanks
• Wrong explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) ALREADY LOGGED IN - This option is incorrect. The SQL3001 error does not indicate that the user is already logged in. This error is related to a different issue.

Option B) UNKNOWN COMMAND - This option is correct. The SQL3001 error typically occurs when the database engine encounters an unknown command or statement. This could happen when executing a query or performing any other database operation.

Option C) SOCKET READ ERROR - This option is incorrect. The SQL3001 error is not related to a socket read error. It is specifically related to an unknown command.

Option D) INVALID AGENT SIGNATURE - This option is incorrect. The SQL3001 error does not indicate an invalid agent signature. It is related to an unknown command.

The correct answer is B) UNKNOWN COMMAND. This option is correct because the SQL3001 error occurs when the database engine encounters an unknown command or statement.

• Thanks
• Wrong explanation