Besides the timestamp, string, and numeric functions, we also provide other functions that can be used to support the use of our database. The functions are as follows:

CURRENT_SCHEMA()It returns the schema’s name first in the search path.
CURRENT_DATABASE()It returns the current database’s name.
NULLIF()It replaces a given value with null if it matches a specific criterion.
COALESCE()It returns the first argument that is not null, while the remaining arguments from the first non-null argument are not evaluated.
pg_total_relation_size()It retrieves the size of a table.
has_schema_privilege()It checks whether the current user has specific privileges on a schema.
pg_get_expr()It retrieves the internal form of an individual expression, such as the default value for a column.
pg_typeof()It retrieves the data type of any given value.