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public interface SQLData
The interface used for the custom mapping of an SQL user-defined type (UDT) to a class in the Java programming language. The class object for a class implementing theSQLData
interface will be entered in the appropriateConnection
object's type map along with the SQL name of the UDT for which it is a custom mapping.Typically, a
SQLData
implementation will define a field for each attribute of an SQL structured type or a single field for an SQLDISTINCT
type. When the UDT is retrieved from a data source with theResultSet.getObject
method, it will be mapped as an instance of this class. A programmer can operate on this class instance just as on any other object in the Java programming language and then store any changes made to it by calling thePreparedStatement.setObject
method, which will map it back to the SQL type.It is expected that the implementation of the class for a custom mapping will be done by a tool. In a typical implementation, the programmer would simply supply the name of the SQL UDT, the name of the class to which it is being mapped, and the names of the fields to which each of the attributes of the UDT is to be mapped. The tool will use this information to implement the
SQLData.readSQL
andSQLData.writeSQL
methods. ThereadSQL
method calls the appropriateSQLInput
methods to read each attribute from anSQLInput
object, and thewriteSQL
method callsSQLOutput
methods to write each attribute back to the data source via anSQLOutput
object.An application programmer will not normally call
SQLData
methods directly, and theSQLInput
andSQLOutput
methods are called internally bySQLData
methods, not by application code.- Since:
- 1.2
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Method Summary
Methods Modifier and Type Method and Description String
getSQLTypeName()
Returns the fully-qualified name of the SQL user-defined type that this object represents.void
readSQL(SQLInput stream, String typeName)
Populates this object with data read from the database.void
writeSQL(SQLOutput stream)
Writes this object to the given SQL data stream, converting it back to its SQL value in the data source.
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Method Detail
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getSQLTypeName
String getSQLTypeName() throws SQLException
Returns the fully-qualified name of the SQL user-defined type that this object represents. This method is called by the JDBC driver to get the name of the UDT instance that is being mapped to this instance ofSQLData
.- Returns:
- the type name that was passed to the method
readSQL
when this object was constructed and populated - Throws:
SQLException
- if there is a database access errorSQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.2
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readSQL
void readSQL(SQLInput stream, String typeName) throws SQLException
Populates this object with data read from the database. The implementation of the method must follow this protocol:- It must read each of the attributes or elements of the SQL type from the given input stream. This is done by calling a method of the input stream to read each item, in the order that they appear in the SQL definition of the type.
- The method
readSQL
then assigns the data to appropriate fields or elements (of this or other objects). Specifically, it must call the appropriate reader method (SQLInput.readString
,SQLInput.readBigDecimal
, and so on) method(s) to do the following: for a distinct type, read its single data element; for a structured type, read a value for each attribute of the SQL type.
SQLInput
reader method on the stream.- Parameters:
stream
- theSQLInput
object from which to read the data for the value that is being custom mappedtypeName
- the SQL type name of the value on the data stream- Throws:
SQLException
- if there is a database access errorSQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.2
- See Also:
SQLInput
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writeSQL
void writeSQL(SQLOutput stream) throws SQLException
Writes this object to the given SQL data stream, converting it back to its SQL value in the data source. The implementation of the method must follow this protocol:
It must write each of the attributes of the SQL type to the given output stream. This is done by calling a method of the output stream to write each item, in the order that they appear in the SQL definition of the type. Specifically, it must call the appropriateSQLOutput
writer method(s) (writeInt
,writeString
, and so on) to do the following: for a Distinct Type, write its single data element; for a Structured Type, write a value for each attribute of the SQL type.- Parameters:
stream
- theSQLOutput
object to which to write the data for the value that was custom mapped- Throws:
SQLException
- if there is a database access errorSQLFeatureNotSupportedException
- if the JDBC driver does not support this method- Since:
- 1.2
- See Also:
SQLOutput
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Nederlandse vertaling
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Bij voorbaat dank.
Document heeft de 11/06/2005 gemaakt, de laatste keer de 04/03/2020 gewijzigd
Bron van het afgedrukte document:https://www.gaudry.be/nl/java-api-rf-java/sql/sqldata.html
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