Import into tables that contain identity columns

You can use the either the SYSCS_UTIL.SYSCS_IMPORT_DATA procedure or the SYSCS_UTIL.SYSCS_IMPORT_DATA_LOBS_FROM_EXTFILE procedure to import data into a table that contains an identity column.

If the identity column is defined as GENERATED ALWAYS, an identity value is generated for a table row whenever the corresponding row field in the input file does not contain a value for the identity column. When a corresponding row field in the input file already contains a value for the identity column, the row cannot be inserted into the table and the import operation will fail. To prevent such scenarios, the following examples show how to specify parameters in the SYSCS_UTIL.SYSCS_IMPORT_DATA and SYSCS_UTIL.SYSCS_IMPORT_DATA_LOBS_FROM_EXTFILE procedures to ignore data for the identity column from the file, or omit the column name from the insert column list.

If the REPLACE parameter is used during import, Derby resets its internal counter of the last identity value for a column to the initial value defined for the identity column.

The following table definition contains an identity column, c2 and is used in the examples below:

CREATE TABLE tab1 (c1 CHAR(30), c2 INT GENERATED ALWAYS AS IDENTITY, 
   c3 REAL, c4 CHAR(1))

Suppose that you want to import data into tab1 from a file myfile.del that does not have identity column information. The myfile.del file contains three fields with the following data:
```
Robert,45.2,J
Mike,76.9,K
Leo,23.4,I   
```
To import the data, you must explicitly list the column names in the tab1 table except for the identity column c2 when you call the procedure. For example:
```
CALL SYSCS_UTIL.SYSCS_IMPORT_DATA (NULL, 'TAB1', 'C1,C3,C4', 
    null, 'myfile.del',null, null, null, 0)
   
```
Suppose that you want import data into tab1 from a file empfile.del that also has identity column information. The file contains three fields with the following data:
```
Robert,1,45.2,J
Mike,2,23.4,I
Leo,3,23.4,I   
```
To import the data, you must explicitly specify an insert column list without the identity column c2 and specify the column indexes without identity column data when you call the procedure. For example:
```
CALL SYSCS_UTIL.SYSCS_IMPORT_DATA (NULL, 'TAB1', 'C1,C3,C4', 
    '1,3,4', 'empfile.del',null, null, null, 0)
```