DBMS – Page 346

How the CHARACTER_LENGTH() Function Works in MySQL

November 19, 2019April 25, 2019 by Ian

In MySQL, the CHARACTER_LENGTH() function returns the length of a string, measured in characters.

CHARACTER_LENGTH() is a synonym for the CHAR_LENGTH() function.

How the SOUNDS LIKE Operator Works in MySQL

February 14, 2020April 24, 2019 by Ian

In MySQL, you can use the SOUNDS LIKE operator to return results that sound like a given word.

This operator works best on strings in the English language (using it with other languages may return unreliable results).

How NOT LIKE Works in MySQL

February 14, 2020April 24, 2019 by Ian

In MySQL, you can use NOT LIKE to perform a negation of the LIKE operator. In other words, NOT LIKE returns the opposite result to LIKE.

If the string matches the pattern provided, the result is 0, otherwise it’s 1.

The pattern doesn’t necessarily need to be a literal string. This function can be used with string expressions and table columns.

How the LIKE Operator Works in MySQL

February 14, 2020April 24, 2019 by Ian

In MySQL, the LIKE operator performs pattern matching using an SQL pattern.

If the string matches the pattern provided, the result is 1, otherwise it’s 0.

The pattern doesn’t necessarily need to be a literal string. This function can be used with string expressions and table columns.

How the REGEX_REPLACE() Function Works in MySQL

April 29, 2021April 22, 2019 by Ian

In MySQL, the REGEXP_REPLACE() function replaces occurrences of the substring within a string that matches the given regular expression pattern.

The whole string is returned along with the replacements.

If there’s no match (i.e. the input string doesn’t contain the substring), the the whole string is returned unchanged.

How the REGEXP_INSTR() Function Works in MySQL

November 19, 2019April 22, 2019 by Ian

In MySQL, the REGEXP_INSTR() function returns the starting index of a substring that matches the regular expression pattern.

The index starts at 1. If there’s no match, the result is 0.

How the REGEXP_SUBSTR() Function Works in MySQL

November 19, 2019April 22, 2019 by Ian

In MySQL, the REGEXP_SUBSTR() function returns the substring that matches the given regular expression pattern.

If there’s no match (i.e. the input string doesn’t contain the substring), the result is NULL.

How NOT RLIKE Works in MySQL

November 19, 2019April 19, 2019 by Ian

In MySQL, NOT RLIKE is a negation of the RLIKE operator.

In other words, any time the RLIKE operator would return 1, NOT RLIKE will return 0.

How NOT REGEXP Works in MySQL

February 14, 2020April 19, 2019 by Ian

In MySQL, NOT REGEXP is a negation of the REGEXP operator.

In other words, if the string matches the regular expression provided, the result is 0, otherwise it’s 1. This is the opposite result to what the REGEXP would return (when it isn’t prefixed with NOT).

How the RLIKE Operator Works in MySQL

February 14, 2020April 18, 2019 by Ian

In MySQL, the RLIKE operator is used to determine whether or not a string matches a regular expression. It’s a synonym for REGEXP_LIKE().

If the string matches the regular expression provided, the result is 1, otherwise it’s 0.