1. What is the SUBSTR
function used for?
The SUBSTR
function is used to extract a substring from a larger string,
based on the starting position and length provided.
2. What happens if the start_position
is greater than the length
of the string?
If the start_position
exceeds the length of the string, SUBSTR
will return an empty string.
3. How does negative
indexing work in the SUBSTR
function?
Negative values for start_position
allow you to start counting from the end of the string. For example:
-1
refers to the last character.-2
refers to the second-last character, and so on.
4. What happens if the length
parameter is omitted?
If length
is omitted, SUBSTR
will extract the substring from the start_position
to the end of the string.
5. What will happen if the
string is NULL
?
If the string is NULL
, SUBSTR
will return NULL
.
6. Can SUBSTR
return a substring from a
specific position to the end of the string?
Yes, if length
is omitted, SUBSTR
will start from the start_position
and continue to the end of the string.
7. Is the SUBSTR
function case-sensitive?
Yes, SUBSTR
is case-sensitive, meaning it treats uppercase and lowercase letters as
distinct characters.
8. Can SUBSTR
be used on columns in a
database table?
Yes, SUBSTR
can be applied to columns in a table to extract substrings from the data stored
in those columns.
9. Can SUBSTR
handle empty strings?
If the input string is empty (''
),
SUBSTR
will
return an empty string.
10. Can SUBSTR
be used with negative length
values?
Yes, you can use negative values for the length
parameter. However, this is
uncommon and should be used with care, as it allows you to extract substrings
from the end of the string.
11. What happens if the length
provided exceeds the number
of remaining characters in the string?
If the length
exceeds the remaining characters in the string, SUBSTR
will return the substring
starting from start_position
up to the end of the string.
12. Is it possible to
extract a substring from the middle of a string using SUBSTR
?
Yes, by specifying a start_position
that is not at the beginning of the string, you can extract a substring from
the middle of a string.
13. Can SUBSTR
be used to remove
characters from the beginning or end of a string?
While SUBSTR
does not "remove" characters, it can effectively extract a part of
the string starting from a specific position, which can serve as a way to
remove unwanted characters from the start or end of a string.
14. Can SUBSTR
be used for string validation?
Yes, SUBSTR
can be combined with other SQL functions like INSTR
to check if certain substrings
exist within a string, thus enabling string validation.
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