Sybase 12.4.2 - Manual (Page 218)

Partial-width insertions
198
Use START ROW ID to specify at which row you want to start the insert. This
allows you to insert into some of the columns in a row with one partial-width
INSERT or LOAD TABLE statement, and insert into the other columns in the
same row with additional INSERT or LOAD TABLE statements.
If you try to insert into a column that already contains data, you get an error.
You must be sure to control the row at which each insertion starts. If you do not
use
START ROW ID , your insertion begins with the next row, and NULLs are
inserted in the remaining columns of the current row, as shown in Figure 5-1.
(The two shading patterns represent data inserted into columns in two separate
insert operations.)
Figure 5-1: Using START ROW ID with partial-width insertions
Note Do not try to perform a partial-width insertion using the INSERT VALUES
command format. Because you cannot specify START ROW ID using this
format, the problem shown in the figure results.
Partial-width insertion rules
Column indexes that are not included in the initial partial-width insert, and
therefore do not already contain data, must allow NULLs. Adaptive Server IQ
inserts NULLs into these column indexes. If they do not allow NULLs, the
insert fails.
When doing partial-width inserts, follow these steps:
1 For the first partial-width insert for each set of rows, do not specify START
ROW ID . Adaptive Server IQ automatically knows what the next available
row is for this insert.