What happens “Update” command is used without where clause ?

It will update all the records with same name in the particular field of the table.

If we dont mention “WHERE” clause in the UPDATE statement, it will update all records satisfying the given condition (if given any ) in the table !

Based on query condition. it will 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 you need to use the where clause.

What is an ABAP/4 Query?
ABAP/4 Query is a powerful tool to generate simple reports without any coding. ABAP/4 Query can generate the following 3 simple reports: Basic List: It is the simple reports. Statistics: Reports with statistical functions like Average, Percentages. Ranked Lists: For analytical reports. – For creating a ABAP/4 Query, programmer has to create user group and a functional group. Functional group can be created using with or without logical database table. Finally, assign user group to functional group. Finally, create a query on the functional group generated.

Difference between transparent tables and pooled tables.

Transparent tables: Transparent tables in the dictionary has a one-to-one relation with the table in database. Its structure corresponds to single database field. Table in the database has the same name as in the dictionary. Transparent table holds application data.

Pooled tables. Pooled tables in the dictionary has a many-to-one relation with the table in database. Table in the database has the different name as in the dictionary. Pooled table are stored in table pool at the database level.

What are indexes?
Indexes are described as a copy of a database table reduced to specific fields. This data exists in sorted form. This sorting form ease fast access to the field of the tables. In order that other fields are also read, a pointer to the associated record of the actual table are included in the index. The indexes are activated along with the table and are created automatically with it in the database.

What are domains and data element?
Domains:Domain is the central object for describing the technical characteristics of an attribute of an business objects. It describes the value range of the field. Data Element: It is used to describe the semantic definition of the table fields like description the field. Data element describes how a field can be displayed to end-user.

What is foreign key relationship?
A relationship which can be defined between tables and must be explicitly defined at field level. Foreign keys are used to ensure the consistency of data. Data entered should be checked against existing data to ensure that there are now contradiction. While defining foreign key relationship cardinality has to be specified. Cardinality mentions how many dependent records or how referenced records are possible.

What is an ABAP data dictionary?
ABAP 4 data dictionary describes the logical structures of the objects used in application development and shows how they are mapped to the underlying relational database in tables/views.

What is the difference between a contract and a scheduling agreement?

A scheduling agreement can be made for Consignment, Subcontracting and stock transfer. A contract, also known as a blanket PO, can be made for standard items and can be restricted to a Value or QTY.