Column substrings in single-byte code sets
You can use column substrings in single-byte code sets.
Suppose that you want to retrieve the customer_num column
and the seventh through ninth bytes of the lname column from
the customer table. To perform this query, use a column substring
for the lname column in your SELECT statement, as follows:
SELECT customer_num, lname[7,9] as lname_subset
FROM customer WHERE lname = 'Albertson'If the lname column
value is
Albertson, the query returns these results.| customer_num | lname_subset |
|---|---|
| 114 | son |
Because the locale supports a single-byte code set,
the preceding query seems to return the seventh through ninth characters
of the name Albertson. Column substrings, however,
are byte based, and the query returns the seventh through ninth bytes
of the name. Because one byte is equal to one character in single-byte
code sets, the distinction between characters and bytes in column
substrings is not apparent in these code sets.