In PostgreSQL, string_to_array() is a string function that allows us to create an array from a string. It splits the string based on the specified delimiter and returns a text array as a result.
If we specify a null delimiter, then each character becomes an element in the array. If the delimiter string is empty, then the whole string becomes a single element in the array.
We also have the option of turning a specific substring into null if required.
In PostgreSQL, the strpos() function returns the first starting position of a given substring within a string.
We pass the string as the first argument and the substring as the second.
Continue readingIn PostgreSQL, we can use the the substr() function to return a substring from a string, based on a starting point. We have the option of specifying how many characters to return.
We pass the string as the first argument and the start position as the second. If we want to specify how long the substring should be, we can pass a third argument that specifies how many characters to return.
The function returns the same result as the substring() function (which uses a slightly different syntax).
In PostgreSQL, the parse_ident() function splits a qualified identifier into an array of identifiers, and removes any quoting of individual identifiers.
We pass the qualified identifier to the function when we call it. We can also specify whether or not to use strict mode.
Continue readingIn PostgreSQL, we can use the regexp_like() function to check whether or not a match of a POSIX regular expression occurs within a given string.
We pass the string as the first argument and the pattern as the second argument. We can also provide a flag as an optional third argument, which determines how the function behaves.
Continue readingIn PostgreSQL, we can use the quote_ident() function to quote identifiers in a SQL statement string.
Quotes are only added if necessary. Any embedded quotes are doubled.
Continue readingIn PostgreSQL, the format() function produces output formatted according to a format string. The first argument is the format string (consisting of one or more format specifiers that start with the % character), and the subsequent arguments are the values to format.
In PostgreSQL, the regexp_instr() function returns the starting or ending position of the N‘th match of a POSIX regular expression pattern to a string. If there’s no match, it returns zero.
We pass the string and pattern as arguments. The function also accepts some optional arguments that allow us to be specific with how the function works.
Continue readingIn PostgreSQL, we can use the substring() function to extract the first substring matching the specified POSIX or SQL regular expression.
In PostgreSQL, the regexp_count() function returns the number of times a given POSIX regular expression pattern matches in a given string.
We pass the string and pattern as arguments. We can also pass an argument to specify where to start the search. Additionally, we also have the option of specifying a flag that changes the function’s behaviour.
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