topic Reg int table declaration in Application Development and Automation Discussions

Reg int table declaration

Former Member — Mon, 14 Apr 2008 06:29:08 GMT

Hi,

What does the following statement mean?

t_tab TYPE STANDARD TABLE OF tp_tab

WITH NON-UNIQUE DEFAULT KEY,

What is the use of using "NON-UNIQUE DEFAULT KEY"?

Thanks,

Chinmaye

Re: Reg int table declaration

Former Member — Mon, 14 Apr 2008 06:30:52 GMT

Hi,

The optional additions UNIQUE or NON-UNIQUE determine whether the key is to be unique or non-unique, that is, whether the table can accept duplicate entries. If you do not specify UNIQUE or NON-UNIQUE for the key, the table type is generic in this respect. As such, it can only be used for specifying types. When you specify the table type simultaneously, you must note the following restrictions:

You cannot use the UNIQUE addition for standard tables. The system always generates the NON-UNIQUE addition automatically.

You must always specify the UNIQUE option when you create a hashed table.

Thanks,

Sriram Ponna.

Re: Reg int table declaration

Former Member — Mon, 14 Apr 2008 06:33:45 GMT

........... With [UNIQUE | NON-UNIQUE] { {KEY comp1 comp2 ...}

| {DEFAULT KEY} } ... .

Definition of a table key in an internal table.

You use UNIQUE and NON-UNIQUE to specify whether the table key is unique or not. For a table key specified with UNIQUE, a row with a certain key field content can only occur once in an internal table of this type. You can only use NON-UNIQUE for standard tables , UNIQUE for hashed tables, and both for sorted tables.

The key fields can be alternatively defined as follows:

Bulleted list of individual components comp1 comp2 ... of the row type behind KEY. Prerequisite is that the row type is structured and that the components are neither table types nor table types containing components.

If the entire table row is defined as a key, you can only specify the pseudo component table_line behind KEY as the only component comp. This is possible for any row types.

Specify the standard key DEFAULT KEY. The standard key fields of a structured row type are all fields that are neither numeric (i, p, f) nor table types. The standard key for non-structured row types is the entire table row if the row type itself is not a table type. If there is no relevant component that applies and the row type itself is a table type, the standard key remains empty. This is only possible for standard tables.

The table key does not have to be specified in the statement TYPES and does not have to be unique. If a table key is not or only partially specified, then the resulting table type is generic and can only be used for typing formal parameters or field symbols. The individual table types are differentiated as follows:

If no key is specified for standard tables, the table type to the key fields is generic. The addition NON-UNIQUE is always implicitly extended for standard tables.

If no key is specified for sorted tables, the table key is completely generic. If only the additions UNIQUE and NON-UNIQUE are omitted, the table key is only generic in regards to uniqueness.

If no key is specified for hashed tables, the table key is completely generic. If the additions UNIQUE and NON-UNIQUE are omitted, the table key is only generic in regards to uniqueness. As hashed tables can only be defined with the addition UNIQUE, a warning is issued by the syntax check.

For the generic table types ANY TABLE and INDEX TABLE, you can specify a key without specifying the uniqueness.

Re: Reg int table declaration

gopi_narendra — Mon, 14 Apr 2008 06:34:48 GMT

Any standard table by default is NON-UNIQUE. You cannot use the UNIQUE addition with a standard table.

This specifies that the internal table t_tab may contain records with the same key fields.

Regards

Gopi

Re: Reg int table declaration

Former Member — Mon, 14 Apr 2008 06:34:48 GMT

Hi,

NON-UNIQUE means -- The internal table accepts duplicate values also.

Re: Reg int table declaration

Former Member — Mon, 14 Apr 2008 06:36:50 GMT

The UNIQUE and NON-UNIQUE additions allow you to specify whether a table with type itabtype may contain two or more records with the same key or not. The following rules apply:

STANDARD TABLE:

The key is always NON-UNIQUE by default. You cannot use the UNIQUE addition with a standard table.

SORTED TABLE:

There is no default setting for sorted tables. If you do not specify UNIQUE or NON-UNIQUE, the system creates a generic table type without a particular uniqueness attribute. You can use generic types to specify the types of generic subroutine parameters.

HASHED TABLE:

There is no default setting for hashed tables. However, you must define a UNIQUE key. The NON-UNIQUE addition is not permitted.

DEFAULT KEY

Effect

The key fields are the standard keys. Note that you can only specify an empty key for tables with access type STANDARD TABLE.

Note

Performance:

In general, the runtime required to access an internal table by its key increases with the length of the table key. The access time improves if the key is as compact as possible (no gaps) and left-justified.

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Edited by: Alvaro Tejada Galindo on Apr 14, 2008 6:16 PM