Occurrence – This helps in specifying the occurrence of the pattern that is to be used while scanning and is a positive integer. In the case of e what we mean is to use a subexpression for extracting the substring from the source string. In the case of c, the pattern matching is case sensitive and this is the default value when any or the argument or parameter is not specified. When I am specified it means that the pattern matching with regular expression should be done in case–insensitive format. It is a string literal having values either c, I, or e each one having its own significance. Parameters or arguments –These are the values that can help in giving extra information about how we should perform the pattern matching. If we specify the value of position such that it has a value greater than the length of the source string then a blank (“”) empty string is what we get in the output. When not specified the default value of position is 1 as the scanning begins from the first character of the source string. This position is character-based which means that even if there are multi-byte characters they are treated as a single character while scanning as a position is not byte-based.

From here onwards the match is made and searched as per the regular expression inside the source string. The index that is position – This is the index +1 value that is the position that will be considered for scanning the matching regular expression. Pattern or regex – This is the regular expression that is abiding by the standards of SQL and is a string literal value.

The source string can be string literal or any column name whose value should be I string datatype or at least compatible with the string data type. Source string – This is the source string in which we want to scan the presence of the matching pattern with regular expressions specified in the command. This operation may involve sum, average, max, min, and other aggregate operators or logical operations such as AND, OR, and NOT. Table name – This is the name of the table from which you will be retrieving the column names or expression values whose regular expression is to be checked.Įxpression – This is the derived value after performing mathematical or logical operations on the column values or string literals of the table. The % stands for only one occurrence of any character. The regex contains the special symbols which have special meanings such as * stands for zero or more occurrence of any characters. Regex – This stands for regular expression that helps in specifying the pattern that we are trying to match and find in the source string or column value or the expression which involves performing multiple mathematical or logical operations on the column value or string literals. In all the above-mentioned syntaxes, the terminologies used are discussed one by one here – SELECT column and expressions FROM table name WHERE expression REGEX_SUBSTR (source string, regex or pattern ]) Working and terminologies explanation The syntax of the REGEX_SUBSTR function – SELECT column and expressions FROM table name WHERE expression LIKE regex SELECT column and expressions FROM table name WHERE expression SIMILAR TO regex Hadoop, Data Science, Statistics & others

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