SQLInput

AI-generated Key Takeaways

• SQLInput is an interface used internally by JDBC drivers for custom mapping of SQL structured types and distinct types to Java objects.

• Developers primarily interact with it indirectly through the SQLData interface.

• SQLInput provides reader methods for various SQL data types like readLong, readBytes, readNClob, etc., returning corresponding Java objects.

• wasNull() method can be used to check if the last value read from the stream was SQL NULL.

• It is crucial to call the reader methods in the order the attributes are defined in the SQL type definition for proper data retrieval.

public interface SQLInput

An input stream that contains a stream of values representing an instance of an SQL structured type or an SQL distinct type. This interface, used only for custom mapping, is used by the driver behind the scenes, and a programmer never directly invokes SQLInput methods. The reader methods (readLong, readBytes, and so on) provide a way for an implementation of the SQLData interface to read the values in an SQLInput object. And as described in SQLData, calls to reader methods must be made in the order that their corresponding attributes appear in the SQL definition of the type. The method wasNull is used to determine whether the last value read was SQL NULL.

When the method getObject is called with an object of a class implementing the interface SQLData, the JDBC driver calls the method SQLData.getSQLType to determine the SQL type of the user-defined type (UDT) being custom mapped. The driver creates an instance of SQLInput, populating it with the attributes of the UDT. The driver then passes the input stream to the method SQLData.readSQL, which in turn calls the SQLInput reader methods in its implementation for reading the attributes from the input stream.

Public Method Summary

abstract Array	readArray() Reads an SQL ARRAY value from the stream and returns it as an Array object in the Java programming language.
abstract InputStream	readAsciiStream() Reads the next attribute in the stream and returns it as a stream of ASCII characters.
abstract BigDecimal	readBigDecimal() Reads the next attribute in the stream and returns it as a java.math.BigDecimal object in the Java programming language.
abstract InputStream	readBinaryStream() Reads the next attribute in the stream and returns it as a stream of uninterpreted bytes.
abstract Blob	readBlob() Reads an SQL BLOB value from the stream and returns it as a Blob object in the Java programming language.
abstract boolean	readBoolean() Reads the next attribute in the stream and returns it as a boolean in the Java programming language.
abstract byte	readByte() Reads the next attribute in the stream and returns it as a byte in the Java programming language.
abstract byte[]	readBytes() Reads the next attribute in the stream and returns it as an array of bytes in the Java programming language.
abstract Reader	readCharacterStream() Reads the next attribute in the stream and returns it as a stream of Unicode characters.
abstract Clob	readClob() Reads an SQL CLOB value from the stream and returns it as a Clob object in the Java programming language.
abstract Date	readDate() Reads the next attribute in the stream and returns it as a java.sql.Date object.
abstract double	readDouble() Reads the next attribute in the stream and returns it as a double in the Java programming language.
abstract float	readFloat() Reads the next attribute in the stream and returns it as a float in the Java programming language.
abstract int	readInt() Reads the next attribute in the stream and returns it as an int in the Java programming language.
abstract long	readLong() Reads the next attribute in the stream and returns it as a long in the Java programming language.
abstract NClob	readNClob() Reads an SQL NCLOB value from the stream and returns it as a NClob object in the Java programming language.
abstract String	readNString() Reads the next attribute in the stream and returns it as a String in the Java programming language.
abstract Object	readObject() Reads the datum at the head of the stream and returns it as an Object in the Java programming language.
abstract Ref	readRef() Reads an SQL REF value from the stream and returns it as a Ref object in the Java programming language.
abstract RowId	readRowId() Reads an SQL ROWID value from the stream and returns it as a RowId object in the Java programming language.
abstract SQLXML	readSQLXML() Reads an SQL XML value from the stream and returns it as a SQLXML object in the Java programming language.
abstract short	readShort() Reads the next attribute in the stream and returns it as a short in the Java programming language.
abstract String	readString() Reads the next attribute in the stream and returns it as a String in the Java programming language.
abstract Time	readTime() Reads the next attribute in the stream and returns it as a java.sql.Time object.
abstract Timestamp	readTimestamp() Reads the next attribute in the stream and returns it as a java.sql.Timestamp object.
abstract URL	readURL() Reads an SQL DATALINK value from the stream and returns it as a java.net.URL object in the Java programming language.
abstract boolean	wasNull() Retrieves whether the last value read was SQL NULL.

Public Methods

public abstract Array readArray ()

Reads an SQL ARRAY value from the stream and returns it as an Array object in the Java programming language.

Returns

• an Array object representing data of the SQL ARRAY value at the head of the stream; null if the value read is SQL NULL

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract InputStream readAsciiStream ()

Reads the next attribute in the stream and returns it as a stream of ASCII characters.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract BigDecimal readBigDecimal ()

Reads the next attribute in the stream and returns it as a java.math.BigDecimal object in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract InputStream readBinaryStream ()

Reads the next attribute in the stream and returns it as a stream of uninterpreted bytes.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract Blob readBlob ()

Reads an SQL BLOB value from the stream and returns it as a Blob object in the Java programming language.

Returns

• a Blob object representing data of the SQL BLOB value at the head of the stream; null if the value read is SQL NULL

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract boolean readBoolean ()

Reads the next attribute in the stream and returns it as a boolean in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns false

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract byte readByte ()

Reads the next attribute in the stream and returns it as a byte in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns 0

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract byte[] readBytes ()

Reads the next attribute in the stream and returns it as an array of bytes in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract Reader readCharacterStream ()

Reads the next attribute in the stream and returns it as a stream of Unicode characters.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract Clob readClob ()

Reads an SQL CLOB value from the stream and returns it as a Clob object in the Java programming language.

Returns

• a Clob object representing data of the SQL CLOB value at the head of the stream; null if the value read is SQL NULL

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract Date readDate ()

Reads the next attribute in the stream and returns it as a java.sql.Date object.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract double readDouble ()

Reads the next attribute in the stream and returns it as a double in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns 0

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract float readFloat ()

Reads the next attribute in the stream and returns it as a float in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns 0

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract int readInt ()

Reads the next attribute in the stream and returns it as an int in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns 0

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract long readLong ()

Reads the next attribute in the stream and returns it as a long in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns 0

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract NClob readNClob ()

Reads an SQL NCLOB value from the stream and returns it as a NClob object in the Java programming language.

Returns

• a NClob object representing data of the SQL NCLOB value at the head of the stream; null if the value read is SQL NULL

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract String readNString ()

Reads the next attribute in the stream and returns it as a String in the Java programming language. It is intended for use when accessing NCHAR,NVARCHAR and LONGNVARCHAR columns.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract Object readObject ()

Reads the datum at the head of the stream and returns it as an Object in the Java programming language. The actual type of the object returned is determined by the default type mapping, and any customizations present in this stream's type map.

A type map is registered with the stream by the JDBC driver before the stream is passed to the application.

When the datum at the head of the stream is an SQL NULL, the method returns null. If the datum is an SQL structured or distinct type, it determines the SQL type of the datum at the head of the stream. If the stream's type map has an entry for that SQL type, the driver constructs an object of the appropriate class and calls the method SQLData.readSQL on that object, which reads additional data from the stream, using the protocol described for that method.

Returns

• the datum at the head of the stream as an Object in the Java programming language;null if the datum is SQL NULL

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract Ref readRef ()

Reads an SQL REF value from the stream and returns it as a Ref object in the Java programming language.

Returns

• a Ref object representing the SQL REF value at the head of the stream; null if the value read is SQL NULL

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract RowId readRowId ()

Reads an SQL ROWID value from the stream and returns it as a RowId object in the Java programming language.

Returns

• a RowId object representing data of the SQL ROWID value at the head of the stream; null if the value read is SQL NULL

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract SQLXML readSQLXML ()

Reads an SQL XML value from the stream and returns it as a SQLXML object in the Java programming language.

Returns

• a SQLXML object representing data of the SQL XML value at the head of the stream; null if the value read is SQL NULL

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract short readShort ()

Reads the next attribute in the stream and returns it as a short in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns 0

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract String readString ()

Reads the next attribute in the stream and returns it as a String in the Java programming language.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract Time readTime ()

Reads the next attribute in the stream and returns it as a java.sql.Time object.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract Timestamp readTimestamp ()

Reads the next attribute in the stream and returns it as a java.sql.Timestamp object.

Returns

• the attribute; if the value is SQL NULL, returns null

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract URL readURL ()

Reads an SQL DATALINK value from the stream and returns it as a java.net.URL object in the Java programming language.

Returns

• a java.net.URL object.

Throws

SQLException	if a database access error occurs, or if a URL is malformed
SQLFeatureNotSupportedException	if the JDBC driver does not support this method

public abstract boolean wasNull ()

Retrieves whether the last value read was SQL NULL.

Returns

• true if the most recently read SQL value was SQL NULL; false otherwise

Throws

SQLException	if a database access error occurs
SQLFeatureNotSupportedException	if the JDBC driver does not support this method