Gbase 8C function / stored procedure parameters (I)

• name： The name of the function to be created （ Can be modified by patterns ）, Value range ： character string ;
• argmode： Mode of function parameters , Value range ：IN、OUT、INOUT perhaps VARIADIC, Default is IN. Only OUT The parameters of the mode can be followed by VARIADIC（VARIADIC Parameters for declaring array types ）, And OUT and INOUT Mode parameters cannot be used in RETURNS TABLE In the function definition of symbol ;
• argname： The name of the function parameter , Value range ： character string ;
• argtype： The data type of the function parameter ;
• default_expr： Default expression for parameter ;
• rettype： The data type of the value returned by the function , If there is OUT or IN OUT Parameters , It can be omitted RETURNS Clause , If not omitted RETURNS Clause must be consistent with the result type represented by the output parameter ： If multiple output parameters , Then for RECORD Otherwise, the type is the same as that of a single output parameter .SETOF The modifier indicates that the function will return a set , Not a single item ;
• column_name： Field name ;
• column_type： Field type ;
• lang_name： The name of the language used to implement the function . It can be SQL,C,internal, Or user-defined process language name . To ensure downward compatibility , The name can be in single quotation marks （ Surround ）. If single quotation mark is used , Then the quotation marks must be capitalized ;
• TRANSFORM { FOR TYPE type_name } [, ... ] }： List of type conversions , Applicable to calls to functions ;
• WINDOW： Indicates that the function is a window function , Usually only used for C Functions written in language . Cannot change when replacing function definitions WINDOW attribute ;
• IMMUTABLE： It means that the function always returns the same result when giving the same parameter value ;
• STABLE： Indicates that the function cannot modify the database , For the same parameter value , In the same table scan , The return value of this function remains unchanged , But the return value may be different SQL Changes between statements ;
• VOLATILE： Indicates that the value of this function can be changed in a table scan , Therefore, no optimization will be done ;
• LEAKPROOF： Point out that the parameters of this function only include the return value .LEAKPROOF It can only be set by the system administrator ;
• CALLED ON NULL INPUT： Indicates that some parameters of the function are NULL Can be called in the normal way . This parameter can be omitted ;