SQLFunction (Hibernate API Documentation) - Hibernate 3.2.3 正式版 API 英文文档

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org.hibernate.dialect.function
Interface SQLFunction

All Known Implementing Classes:: AnsiTrimEmulationFunction, CastFunction, CharIndexFunction, ConvertFunction, DerbyDialect.DerbyTrimFunctionEmulation, NoArgSQLFunction, NvlFunction, PositionSubstringFunction, SQLFunctionTemplate, StandardSQLFunction, VarArgsSQLFunction

public interface SQLFunction

Provides support routines for the HQL functions as used in the various SQL Dialects Provides an interface for supporting various HQL functions that are translated to SQL. The Dialect and its sub-classes use this interface to provide details required for processing of the function.

Author:: David Channon

Method Summary

Type getReturnType(Type columnType, Mapping mapping)
          The return type of the function.

boolean hasArguments()
          Does this function have any arguments?

boolean hasParenthesesIfNoArguments()
          If there are no arguments, are parens required?

String render(List args, SessionFactoryImplementor factory)
          Render the function call as SQL fragment.

Method Detail

getReturnType

public Type getReturnType(Type columnType,
                          Mapping mapping)
                   throws QueryException

The return type of the function. May be either a concrete type which is preset, or variable depending upon the type of the first function argument.

Parameters:: columnType - the type of the first argument; mapping - The mapping source.
Returns:: The type to be expected as a return.
Throws:: QueryException - Indicates an issue resolving the return type.

hasArguments

public boolean hasArguments()

Does this function have any arguments?

Returns:: True if the function expects to have parameters; false otherwise.

hasParenthesesIfNoArguments

public boolean hasParenthesesIfNoArguments()

If there are no arguments, are parens required?

Returns:: True if a no-arg call of this function requires parentheses.

render

public String render(List args,
                     SessionFactoryImplementor factory)
              throws QueryException

Render the function call as SQL fragment.

Parameters:: args - The function arguments; factory - The SessionFactory
Returns:: The rendered function call
Throws:: QueryException - Indicates a problem rendering the function call.