Sample Exam Questions
From the objective of OSS-DB Exam Silver
S3.2 Functions and operators (String functions)
Sample Question
3.46
In the following descriptions of string functions, choose three that are appropriate.
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The character_length function can be used to obtain the byte length of a string.
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The substring function can retrieve a substring, such as the second to fifth characters of a string.
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The lower function can be used to determine if a string is made up of all lowercase letters.
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The trim function returns a string with whitespace removed from both ends of the string.
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The replace function can replace characters in a string, for example, changing all a's to A's.
※This sample exam is different from those that appear in the actual OSS-DB Exam.
2024/05/02
Answer and Explanation
character_length is a function that returns the length of a string, in characters. It returns the number of characters, regardless of encoding, even for multibyte characters such as Japanese.
substring is a function that retrieves a substring. A typical use is to specify a starting point and a number of characters. For example, substring(col_name, 2, 4) retrieves four characters starting from the second (that is, from the second to fifth characters) of the string in the col_name column. Another use is to retrieve a substring that matches a regular expression.
The lower function converts all uppercase characters in a string to lowercase (leaving all other characters intact). For example, lower('Abc1') returns 'abc1'.
The trim function removes whitespace from both ends of a string. You can also specify options to remove only the leading or trailing whitespace, or remove a specified character instead of whitespace.
The replace function converts all occurrences of a specified string that appear in a string to another. For example, replace('abcayz', 'a', 'A') returns 'AbcAyz'.
So the correct answers are B, D, and E.
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