Learning PostgreSQL

Function handling

For calling stored procedures, JDBC provides the CallableStatement interface, which extends PreparedStatement. The API defines two escape syntaxes, which can be used to call a function on the database:

• {? = call <procedure-name>[(?, ?, …)]}
• {call <procedure-name>[(?, ?, …)]}

The first form includes a return parameter, while the second one does not. The list of parameters passed to the function can contain both input and output parameters. If a function does not expect any parameters, it can be left out completely.

Examples of function handling are as follows:

• {? = call random}: A call to a function without parameters
• {call setval(?, ?)}: A call without a return parameter
• {? = call substring(?, ?, ?)}: A call with the return parameter ...