Gbase 8C system table PG_ cast

pg_cast The system table stores the conversion relationship between data types .

name	type	quote	describe
oid	oid		Row identifier （ Hidden attribute , Must be explicitly selected to display ）
castsource	oid	pg_type.oid	Source data type OID
casttarget	oid	pg_type.oid	Target data type OID
castfunc	oid	pg_proc.oid	Of the function that performs the transformation OID. If the conversion method does not need a function, store 0.
castcontext	char		Indicates the environment in which the transformation can be invoked . e The representation can only be used as an explicit conversion （ Use CAST or :: grammar ）. a Indicates that... Is implicitly called when assigning a value to the target column , As with explicit calls . i Indicates that... Is implicitly called in an expression , Like other transformations .
castmethod	char		Indicates how the transformation is performed . f Indicate the use of castfunc Function specified in . i Indicates the use of input / Output function . b Indicates that the type is binary convertible , Therefore, there is no need to convert .