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Explain “Commit” and “Roll back”
The Oracle RDBMS provides a transaction model based on a unit
of work. The PL/SQL language supports most, but not all, of
the database model for transactions (you cannot, for example,
ROLLBACK FORCE). Transactions begin with the first change to
data and end with either a COMMIT or ROLLBACK.
COMMIT makes the database changes permanent and visible to
other database sessions.
ROLLBACK undoes the changes made in the current transaction
either to the beginning of the transaction or to a savepoint.
A savepoint is a named processing point in a transaction,
created with the SAVEPOINT statement. Rolling back to a
savepoint is a partial rollback of a transaction, wiping out
all changes (and savepoints) that occurred later than the
named savepoint.
Q ) when spool buffer is full and new spool request is raised
what happens to the request?where does the request stored?
The new spool request will be in the queue.If it is urgent
request then the current request will be be stoped and
newrequest will be send.
Select statement to read data into internal tables. Types of Select statements
SELECT * FROM ------ INTO itab.
ENDSELECT.
What are the tools used in SAP Implementation? How do you create Alert Messages?
One of the Tools being used for SAP Implemention is QuickSizer, which is used to size the SAP Server based on number of users using various modules in SAP.
Alert Message is created in the CCMS monitor using TCodes RZ20 and RZ21. The values for Alert AutoReaction Methods are defined using the TCode RZ21, while this particular method is assigned to the Monitoring Tree Element (MTE) in the TCode RZ20.
One as well can have an Alert Management System, where alerts from the Entire Landscape can be configured in a Central Moitoring System from where it can trigger a alert mail or SMS to the concerned Administrator
whats the difference between R3trans and Tp in SAP-DBA?
R/3trans is the r/3 system transport program which can be used for transporting data between different sap systems ,even when they dont belong to the same group .R3trans normally is not used directorly but called from the tp controle program or by the R/3 upgrade.Tp is the basic tool for the transporting the request.
What are logical databases?
Logical databases are special ABAP programs that retrieve data and make it available to application programs. The most common use of logical databases is still to read data from database tables by linking them to executable ABAP programs.
Logical databases contain Open SQL statements that read data from the database. You do not therefore need to use SQL in your own programs. The logical database reads the program, stores them in the program if necessary, and then passes them line by line to the application program or the function module LDB_PROCESS using an interface work area.
A logical database provides a particular view of database tables in the R/3 System. It is always worth using logical databases if the structure of the data that you want to read corresponds to a view available through a logical database.
The data structure in a logical database is hierarchical. Many tables in the R/3 System are linked to each other using foreign key relationships. Some of these dependencies form tree-like hierarchical structures. Logical databases read data from database tables that are part of these structures.
Difference between “Insert”, “Update” and “Modify”
INSERT - Add a new record into the database table.
MODIFY - If record is available it modifies otherwise it wont modify.
UPDATE - If record is available its update the record otherwise it creates a new record.
What is “Group by” in Select statement?
Group by is used to fetch a unique data from a column
What happens “Update” command is used without where clause ?
Based on query condition. it wil update all the fields which are mentioned in the query.
ex: update employee set firstname= @firstname,lastname=@lastname where employee_id =@employee_id.
so in the above case nothing wil be happen if you used where clause or not.
if you have many statements in the query u need to use the where clause |
