What is the use of Regexp_substr in Oracle?

REGEXP_SUBSTR extends the functionality of the SUBSTR function by letting you search a string for a regular expression pattern. It is also similar to REGEXP_INSTR , but instead of returning the position of the substring, it returns the substring itself.

What is Regexp_substr?

The Oracle REGEXP_SUBSTR() function is an advanced version of the SUBSTR() function that allows you to search for substrings based on a regular expression. Instead of returning the position of the substring, it returns a portion of the source string that matches the regular expression.

What is the use of Instr in SQL?

The INSTR functions search string for substring . The function returns an integer indicating the position of the character in string that is the first character of this occurrence.

What is Regexp_substr in SQL?

REGEXP_SUBSTR extends the functionality of the SUBSTR function by letting you search a string for a regular expression pattern. It is also similar to REGEXP_INSTR , but instead of returning the position of the substring, it returns the substring itself. pattern is the regular expression.

What is REGEXP_SUBSTR in SQL?

What is connect by root?

CONNECT_BY_ROOT is a unary operator that is valid only in hierarchical queries. When you qualify a column with this operator, Oracle returns the column value using data from the root row. This operator extends the functionality of the CONNECT BY [ PRIOR ] condition of hierarchical queries.

What is level and connect by in Oracle?

The term LEVEL refers to a Pseudocolumn in Oracle which is used in a hierarchical query to identify the hierarchy level (parent->child) in numeric format. The CONNECT BY clause defines the hierarchical relationship between the parent rows and the child rows of the hierarchy.

What is the purpose of substr () and Instr () functions?

The INSTR function accepts two arguments: The str is the string that you want to search in. The substr is the substring that you want to search for.

What is dual DBMS?

The DUAL is special one row, one column table present by default in all Oracle databases. The owner of DUAL is SYS (SYS owns the data dictionary, therefore DUAL is part of the data dictionary.) MySQL allows DUAL to be specified as a table in queries that do not need data from any tables.