Can you use try _ cast in PostgreSQL?
It’s hard to wrap something like SQL Server’s TRY_CAST into a generic PostgreSQL function. Input and output can be any data type, but SQL is strictly typed and Postgres functions demand that parameter and return types are declared at creation time.
How are input and output types different in PostgreSQL?
Input and output can be any data type, but SQL is strictly typed and Postgres functions demand that parameter and return types are declared at creation time. Postgres has the concept of polymorphic types, but function declarations accept at most one polymorphic type. The manual:
How to call a function with a NULL parameter?
In short, the function is not executed. You have to remove the STRICT parameter to be able to pass a NULL value. You can also update the function to default to a value if null is supplied to allow for optional parameters. CREATE OR REPLACE FUNCTION MyTable_UPDATE ( _ID int, _Description text default null )
What happens when you pass a null value to a function?
If this parameter is specified, the function is not executed when there are null arguments; instead a null result is assumed automatically. In short, the function is not executed. You have to remove the STRICT parameter to be able to pass a NULL value.
Is there extra cast to text in SQL?
The extra cast to text means extra cost (though not much). Polymorphism also adds a bit of overhead. But the moderately expensive parts are the dynamic SQL we need, the involved string concatenation and, most of all, exception handling. That said, this little function can be used for any combination of types including array types.
How to convert one data type to another in PostgreSQL?
There are many cases that you want to convert a value of one data type into another. PostgreSQL provides you with the CAST operator that allows you to do this. First, specify an expression that can be a constant, a table column, an expression that evaluates to a value. Then, specify the target data type to which you want to convert the result