Which three tasks can be performed using regular expression support in Oracle Database
10g? (Choose three.)
A.
it can be used to find out the total length of the string.
B.
it can be used for string manipulation and searching operations.
C.
it can be used to format the output for a column or expression having string data.
D.
it can be used to find and replace operations for a column or expression having string
data.
E.
it can be used to concatenate two strings.
Oracle PL/SQL LENGTH function returns the length of the specified string.
The Oracle/PLSQL CONCAT function allows you to concatenate two strings together.
A regular expression (regex or regexp for short) is a special text string for describing a search pattern.
Why A is incorrect? Did I misunderstand something?
Based on Oracle Documentation, The LENGTH functions return the length of char. LENGTH calculates length using characters as defined by the input character set. LENGTHB uses bytes instead of characters. LENGTHC uses Unicode complete characters. LENGTH2 uses UCS2 code points. LENGTH4 uses UCS4 code points.
char can be any of the datatypes CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, or NCLOB. The return value is of datatype NUMBER. If char has datatype CHAR, then the length includes all trailing blanks. If char is null, then this function returns null.
https://docs.oracle.com/cd/B19306_01/server.102/b14200/functions076.htm
Why D is incorrect? CONCAT() is used to concatenate strings.
Does regular expressions support in CONCAT?
SQL Regular Expression Functions
REGEXP_LIKE : This function searches a character column for a pattern. Use this function in the WHERE clause of a query to return rows matching the regular expression you specify.
REGEXP_REPLACE : This function searches for a pattern in a character column and replaces each occurrence of that pattern with the pattern you specify.
REGEXP_INSTR : This function searches a string for a given occurrence of a regular expression pattern. You specify which occurrence you want to find and the start position to search from. This function returns an integer indicating the position in the string where the match is found.
REGEXP_SUBSTR : This function returns the actual substring matching the regular expression pattern you specify.