In PostgreSQL, we can use the unnest() function to expand an array into a set of rows. We pass the array as an argument, and the function returns each element on a separate row.
We can use the function on multi dimensional arrays, and it’s also possible to use it to unnest multiple arrays by including it in the FROM clause of a query.
On the surface, PostgreSQL’s quote_literal() and quote_nullable() functions appear to do the same thing. But there is a difference.
It all comes down to how they deal with null arguments; quote_literal() returns null while quote_nullable() returns the string NULL.
If you’re getting an error that reads ‘time field value out of range‘ in PostgreSQL while using the make_time() function, it’s probably because one or more of the time parts you’re providing is out of the accepted range for that time part.
To fix this issue, be sure that each time part you provide is within the valid range for that time part.
PostgreSQL has a normalize() function that converts a string to the specified Unicode normalization form.
The function can only be used when the server encoding is UTF8.
In PostgreSQL, we can use the character_length() function to return the number of characters in a given string.
It accepts one argument; the string for which to return the length.
The character_length() function is a synonym for the char_length() function and so both do the same thing. We can also use the length() function to get the same result.
In PostgreSQL the length() function returns the number of characters in a given string.
We pass the string as an argument and the function returns the number of characters as an integer.
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.