# Interface SQLInput

All Known Implementing Classes:
  `SQLInputImpl`

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.

Since:
  1.2

- ## Method Summary

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

- ## Method Details

  - ### readString

    String readString() throws SQLException
    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
    Since:
      1.2

  - ### readBoolean

    boolean readBoolean() throws SQLException
    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
    Since:
      1.2

  - ### readByte

    byte readByte() throws SQLException
    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
    Since:
      1.2

  - ### readShort

    short readShort() throws SQLException
    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
    Since:
      1.2

  - ### readInt

    int readInt() throws SQLException
    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
    Since:
      1.2

  - ### readLong

    long readLong() throws SQLException
    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
    Since:
      1.2

  - ### readFloat

    float readFloat() throws SQLException
    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
    Since:
      1.2

  - ### readDouble

    double readDouble() throws SQLException
    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
    Since:
      1.2

  - ### readBigDecimal

    BigDecimal readBigDecimal() throws SQLException
    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
    Since:
      1.2

  - ### readBytes

    byte[] readBytes() throws SQLException
    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
    Since:
      1.2

  - ### readDate

    Date readDate() throws SQLException
    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
    Since:
      1.2

  - ### readTime

    Time readTime() throws SQLException
    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
    Since:
      1.2

  - ### readTimestamp

    Timestamp readTimestamp() throws SQLException
    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
    Since:
      1.2

  - ### readCharacterStream

    Reader readCharacterStream() throws SQLException
    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
    Since:
      1.2

  - ### readAsciiStream

    InputStream readAsciiStream() throws SQLException
    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
    Since:
      1.2

  - ### readBinaryStream

    InputStream readBinaryStream() throws SQLException
    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
    Since:
      1.2

  - ### readObject

    Object readObject() throws SQLException
    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
    Since:
      1.2

  - ### readRef

    Ref readRef() throws SQLException
    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
    Since:
      1.2

  - ### readBlob

    Blob readBlob() throws SQLException
    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
    Since:
      1.2

  - ### readClob

    Clob readClob() throws SQLException
    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
    Since:
      1.2

  - ### readArray

    Array readArray() throws SQLException
    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
    Since:
      1.2

  - ### wasNull

    boolean wasNull() throws SQLException
    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
    Since:
      1.2

  - ### readURL

    URL readURL() throws SQLException
    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
    Since:
      1.4

  - ### readNClob

    NClob readNClob() throws SQLException
    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
    Since:
      1.6

  - ### readNString

    String readNString() throws SQLException
    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
    Since:
      1.6

  - ### readSQLXML

    SQLXML readSQLXML() throws SQLException
    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
    Since:
      1.6

  - ### readRowId

    RowId readRowId() throws SQLException
    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
    Since:
      1.6

  - ### readObject

    default <T> T readObject(Class<T> type) throws SQLException
    Reads the next attribute in the stream and returns it as an `Object` in the Java programming language. The actual type of the object returned is determined by the specified Java data type, 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 attribute at the head of the stream is an SQL `NULL` the method returns `null`. If the attribute is an SQL structured or distinct type, it determines the SQL type of the attribute 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.

    The default implementation will throw `SQLFeatureNotSupportedException`

    Type Parameters:
      `T` - the type of the class modeled by this Class object
    Parameters:
      `type` - Class representing the Java data type to convert the attribute to.
    Returns:
      the attribute at the head of the stream as an `Object` in the Java programming language;`null` if the attribute is SQL `NULL`
    Throws:
      `SQLException` - if a database access error occurs
      `SQLFeatureNotSupportedException` - if the JDBC driver does not support this method
    Since:
      1.8