Tag: functions

A Brief Overview of SUBSTR() in PostgreSQL

Posted on by Ian

In 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).

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A Quick Look at PostgreSQL’s REGEXP_LIKE() Function

Posted on by Ian

In 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.

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Understanding PostgreSQL’s REGEXP_INSTR() Function

Posted on by Ian

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.

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A Quick Look at PostgreSQL’s REGEXP_COUNT() Function

Posted on by Ian

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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