Extract statement and insert statement

Question

can anyone explain me the use of this insert statement and extract statement.
INSERT lfa1-name1 INTO fg01
extract fg01.
thanks
phyrose

Answer 1

Hi,
       From f1 help....
EXTRACT
Basic form
EXTRACT fg.
Effect
Writes all fields of the field group fg (FIELD-GROUPS) as an entry in asequential dataset. If you have defined a field group HEADER,its fields precede each entry as a sort key. Afterwards, you canuse SORT and LOOP ... ENDLOOP to sort or process the datasetrespectively. No further EXTRACT statements are possible afterthis.
Notes
General:
As soon as you have extracted a dataset using EXTRACT, you canno longer extend the field group using INSERT. In particular, you cannot change the HEADERfield group at all after the first EXTRACT (regardless of thefield group to which it applied).
Large extract datasets are not stored in main memory. Instead, theyare kept in an external auxiliary file. You can set the directory inwhich this file is created using the SAP profile parameterDIR_EXTRACT. The default directory is the SAP data directory(SAP profile parameter DIR_DATA).
Notes
Runtime errors:
EXTRACT_AFTER_SORT/LOOP: EXTRACT after SORT, orLOOP. EXTRACT_BUFFER_NO_ROLL: Unable to create the required main
EXTRACT_FIELD_TOO_LARGE: Occupied length of a field is toolarge.
EXTRACT_HEADER_NOT_UNIQUE: Field group HEADER wasmodified after an EXTRACT statement.
EXTRACT_OPEN_EXTRACTFILE_OPEN:
Error opening the external extract dataset file.
EXTRACT_RESOURCEHANDLER_FAILED: Error deleting the externalextract dataset file.
EXTRACT_TOO_LARGE: Total length of the entry for extraction(including HEADER fields) is too large.
Additional help
Filling anExtract with Data
Extracts
Since internal tables have fixed line structures, they are not suited to handle data sets with varying structures. Instead, you can use extract datasets for this purpose.
An extract is a sequential dataset in the memory area of the program. You can only address the entries in the dataset within a special loop. The index or key access permitted with internal tables is not allowed. You may only create one extract in any ABAP program. The size of an extract dataset is, in principle, unlimited. Extracts larger than 500KB are stored in operating system files. The practical size of an extract is up to 2GB, as long as there is enough space in the filesystem.
An extract dataset consists of a sequence of records of a pre-defined structure. However, the structure need not be identical for all records. In one extract dataset, you can store records of different length and structure one after the other. You need not create an individual dataset for each different structure you want to store. This fact reduces the maintenance effort considerably.
In contrast to internal tables, the system partly compresses extract datasets when storing them. This reduces the storage space required. In addition, you need not specify the structure of an extract dataset at the beginning of the program, but you can determine it dynamically during the flow of the program.
You can use control level processing with extracts just as you can with internal tables. The internal administration for extract datasets is optimized so that it is quicker to use an extract for control level processing than an internal table.
Procedure for creating an extract:
Define the record types that you want to use in your extract by declaring them as field groups. The structure is defined by including fields in each field group.
Defining an Extract
Fill the extract line by line by extracting the required data.
Filling an Extract with Data
Once you have filled the extract, you can sort it and process it in a loop. At this stage, you can no longer change the contents of the extract.
Processing Extracts
INSERT Statement
The INSERT statement is used to insert values into a single database table.
<insert statement> ::= INSERT INTO <table name> <insert column list> <insert source>.
<insert source> ::= VALUES '(' <value> ( ',' <value> )* ')'
                            | <query specification>.
<value> ::= <value expression>
                | <dynamic parameter specification>
                | NULL.
<insert column list> ::= '(' <column name> ( ',' <column name> )* ')'.
In Open SQL the <insert column list> is not optional.
You cannot specify string literals as values for CLOB columns. Hex literals are not supported in Open SQL.
Examples
INSERT INTO employees (employee_id, employee_name)
              VALUES (4711, 'John Smith')
Inserting Values. A new row is inserted into the table employees with the values 4711 and 'John Smith' for the columns employee_id and employee_name respectively.
INSERT INTO well_paid_employees (employee_id, salary)
             SELECT employee_id, salary
                            FROM employees
                            WHERE salary > ?
Inserting the Result of a Query.  The employee_idand the salaryof all employees from table employeeswith a salary exceeding a certain value are inserted into the table well_paid_employees.
Regards