In PostgreSQL, the char_length() function returns the number of characters in a string. We pass the string as an argument and the function returns the number of characters in that string.
We can also use character_length() and length() to get the same result.
If you’re getting an error that reads something like ‘column “c1” cannot be cast automatically to type text[]‘ in PostgreSQL, it could be that you’re trying to change a column’s type to one where the existing type can’t be implicitly cast to.
To fix this issue, try explicitly casting the column to the desired data type.
In PostgreSQL, we can use the replace() function to replace a given substring within a string with another substring.
The function replaces all occurrences of the substring. If the substring doesn’t exist in the string, then the original string is returned unchanged.
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.
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).
If you’re getting an error that reads “function array_sample(numeric, integer) does not exist” when using the array_sample() function in PostgreSQL, it’s probably because your first argument is a numeric type instead of an array.
The first argument for this function must be an array.
To fix this error, be sure that your first argument to array_sample() is an array, not a numeric value.
In MySQL we can use the CREATE EVENT statement to create scheduled events. As with many CREATE ... statements, we have the option of using the IF NOT EXISTS clause to specify that the object should only be created if it doesn’t already exist.
Of course, we wouldn’t normally be trying to create an event if we know that it already exists. But there may be times where we’re not sure, and we want our code to handle this scenario without throwing an error if an event with the same name already exists. This is common when creating scripts that are designed to be run across multiple environments. That’s where the IF NOT EXISTS clause can come in handy.
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.
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.