In PostgreSQL we can use the left() function to get the specified number of leftmost characters in a given string.
We have the option of specifying the number of characters to return from the left or the number of characters to omit from the right. We do this by specifying a positive integer (to return n number of leftmost characters) or a negative integer (to return everything except n rightmost characters).
Continue readingIn PostgreSQL, erfc() is a mathematical function that provides the mathematical complementary error function, without loss of precision for large inputs. It returns 1 - erf(x).
The erfc() function was introduced in PostgreSQL 16, which was released on September 14th 2023.
In PostgreSQL, erf() is a mathematical function that provides the standard mathematical error function.
The erf() function was introduced in PostgreSQL 16, which was released on September 14th 2023.
In PostgreSQL, we can use the regexp_replace() function to replace a substring within a given string, based on a given POSIX regular expression. We can specify that all matches are replaced or just the first match.
We pass the string as the first argument, the pattern as the second, and the replacement text as the third argument. We also have the option of specifying the start position as the fourth argument, and we can specify a flag to determine how the function behaves.
Continue readingMost SQL databases have a handful of “ranking” functions that allow us to rank data. By “handful”, I mean there’s a common set of around six SQL rank functions that most of the major RDBMSs appear to support.
SQL rank functions allow us to assign ranks or row numbers to result sets.
Continue readingIn PostgreSQL, we can use the chr() function to return a character based on its code.
The code is provided as an integer argument, and the function returns the character that the code represents. When using UTF8 encoding the argument is treated as a Unicode code point, otherwise it must designate an ASCII character.
Continue readingPostgreSQL has a unistr() function that evaluates escaped Unicode characters in its argument and returns the result as text.
In PostgreSQL, gcd() is a mathematical function that returns the greatest common divisor. We pass two numbers and the function returns the largest positive number that divides both inputs with no remainder.
In PostgreSQL, lcm() is a mathematical function that returns the least common multiple. We pass two numbers and the function returns the smallest strictly positive number that is an integral multiple of both inputs.
PostgreSQL has a translate() function which replaces certain characters in a string with certain other characters.
We specify the characters in the string that we want to replace, as well as the characters that we want to replace them with. The function then performs the translation and returns the string with the replaced characters.
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