INDEX

[Former Member]

1)while creatint 2ndary index there is an radio button called unique index & non unique index. what does it actuall mean.? explain cleary both

2) if i click on unique index is it mandatary to gv client field? why so explain it plz..

[former_member195698]

You can keep your cursor and click F1. It gives the details of the use of NON-UNIQUE index and UNIQUE Index.

E.g.

Flag for UNIQUE indexes

Definition

Indicator whether or not the index on the database is created as a unique index.

For a unique index, each value combination for the index fields can be contained at most once in the table. The index fields in this case have key attribute, that is they already uniquely identify each record of the table.

The uniqueness of the value combinations for the index fields is checked automatically by the database system. If there is a violation (for example in an INSERT operation) an error message (DUPLICATE RECORD) is given. The database system thus prevents you from inserting duplicate records for the index fields of a unique index. This function requires that you always create a unique index in the database.

It is of no importance for the accessing speed whether or not an index is defined as a unique index.

Note: A UNIQUE index for a client-specific table must contain the client field.

Regard,

Abhishek

[Former Member]

An entry in an index can refer to several records that have the same values for the index fields. A unique index does not permit these multiple entries. The index fields of a unique index thus have key function, that is they already uniquely identify each record of the table.

The primary index of a table is always a unique index since the index fields form the key of the table, uniquely identifying each data record.

You can define a secondary index as a unique index when you create it. This ensures that there are no double records in the table fields contained in the index. An attempt to maintain an entry violating this condition in the table results in termination due to a database error.

The accessing speed does not depend on whether or not an index is defined as a unique index. A unique index is simply a means of defining that certain field combinations of data records in a table are unique.

A unique index for a client-dependent table must contain the client field.