# Interface ParameterMetaData

All Superinterfaces:
  `Wrapper`

public interface ParameterMetaData extends Wrapper
An object that can be used to get information about the types and properties for each parameter marker in a `PreparedStatement` object. For some queries and driver implementations, the data that would be returned by a `ParameterMetaData` object may not be available until the `PreparedStatement` has been executed.

Some driver implementations may not be able to provide information about the types and properties for each parameter marker in a `CallableStatement` object.

Since:
  1.4

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final int`
  `parameterModeIn`
  The constant indicating that the parameter's mode is IN.
  `static final int`
  `parameterModeInOut`
  The constant indicating that the parameter's mode is INOUT.
  `static final int`
  `parameterModeOut`
  The constant indicating that the parameter's mode is OUT.
  `static final int`
  `parameterModeUnknown`
  The constant indicating that the mode of the parameter is unknown.
  `static final int`
  `parameterNoNulls`
  The constant indicating that a parameter will not allow `NULL` values.
  `static final int`
  `parameterNullable`
  The constant indicating that a parameter will allow `NULL` values.
  `static final int`
  `parameterNullableUnknown`
  The constant indicating that the nullability of a parameter is unknown.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `String`
  `getParameterClassName(int param)`
  Retrieves the fully-qualified name of the Java class whose instances should be passed to the method `PreparedStatement.setObject`.
  `int`
  `getParameterCount()`
  Retrieves the number of parameters in the `PreparedStatement` object for which this `ParameterMetaData` object contains information.
  `int`
  `getParameterMode(int param)`
  Retrieves the designated parameter's mode.
  `int`
  `getParameterType(int param)`
  Retrieves the designated parameter's SQL type.
  `String`
  `getParameterTypeName(int param)`
  Retrieves the designated parameter's database-specific type name.
  `int`
  `getPrecision(int param)`
  Retrieves the designated parameter's specified column size.
  `int`
  `getScale(int param)`
  Retrieves the designated parameter's number of digits to right of the decimal point. 0 is returned for data types where the scale is not applicable.
  `int`
  `isNullable(int param)`
  Retrieves whether null values are allowed in the designated parameter.
  `boolean`
  `isSigned(int param)`
  Retrieves whether values for the designated parameter can be signed numbers.

  ### Methods declared in interface Wrapper

  `isWrapperFor, unwrap`
  Modifier and Type
  Method
  Description
  `boolean`
  `isWrapperFor(Class<?> iface)`
  Returns true if this either implements the interface argument or is directly or indirectly a wrapper for an object that does.
  `<T> T`
  `unwrap(Class<T> iface)`
  Returns an object that implements the given interface to allow access to non-standard methods, or standard methods not exposed by the proxy.

- ## Field Details

  - ### parameterNoNulls

    static final int parameterNoNulls
    The constant indicating that a parameter will not allow `NULL` values.
    See Also:
      - Constant Field Values

  - ### parameterNullable

    static final int parameterNullable
    The constant indicating that a parameter will allow `NULL` values.
    See Also:
      - Constant Field Values

  - ### parameterNullableUnknown

    static final int parameterNullableUnknown
    The constant indicating that the nullability of a parameter is unknown.
    See Also:
      - Constant Field Values

  - ### parameterModeUnknown

    static final int parameterModeUnknown
    The constant indicating that the mode of the parameter is unknown.
    See Also:
      - Constant Field Values

  - ### parameterModeIn

    static final int parameterModeIn
    The constant indicating that the parameter's mode is IN.
    See Also:
      - Constant Field Values

  - ### parameterModeInOut

    static final int parameterModeInOut
    The constant indicating that the parameter's mode is INOUT.
    See Also:
      - Constant Field Values

  - ### parameterModeOut

    static final int parameterModeOut
    The constant indicating that the parameter's mode is OUT.
    See Also:
      - Constant Field Values

- ## Method Details

  - ### getParameterCount

    int getParameterCount() throws SQLException
    Retrieves the number of parameters in the `PreparedStatement` object for which this `ParameterMetaData` object contains information.
    Returns:
      the number of parameters
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4

  - ### isNullable

    int isNullable(int param) throws SQLException
    Retrieves whether null values are allowed in the designated parameter.
    Parameters:
      `param` - the first parameter is 1, the second is 2, ...
    Returns:
      the nullability status of the given parameter; one of `ParameterMetaData.parameterNoNulls`, `ParameterMetaData.parameterNullable`, or `ParameterMetaData.parameterNullableUnknown`
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4

  - ### isSigned

    boolean isSigned(int param) throws SQLException
    Retrieves whether values for the designated parameter can be signed numbers.
    Parameters:
      `param` - the first parameter is 1, the second is 2, ...
    Returns:
      `true` if so; `false` otherwise
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4

  - ### getPrecision

    int getPrecision(int param) throws SQLException
    Retrieves the designated parameter's specified column size.

    The returned value represents the maximum column size for the given parameter. For numeric data, this is the maximum precision. For character data, this is the length in characters. For datetime datatypes, this is the length in characters of the String representation (assuming the maximum allowed precision of the fractional seconds component). For binary data, this is the length in bytes. For the ROWID datatype, this is the length in bytes. 0 is returned for data types where the column size is not applicable.

    Parameters:
      `param` - the first parameter is 1, the second is 2, ...
    Returns:
      precision
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4

  - ### getScale

    int getScale(int param) throws SQLException
    Retrieves the designated parameter's number of digits to right of the decimal point. 0 is returned for data types where the scale is not applicable.
    Parameters:
      `param` - the first parameter is 1, the second is 2, ...
    Returns:
      scale
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4

  - ### getParameterType

    int getParameterType(int param) throws SQLException
    Retrieves the designated parameter's SQL type.
    Parameters:
      `param` - the first parameter is 1, the second is 2, ...
    Returns:
      SQL type from `java.sql.Types`
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4
    See Also:
      - `Types`

  - ### getParameterTypeName

    String getParameterTypeName(int param) throws SQLException
    Retrieves the designated parameter's database-specific type name.
    Parameters:
      `param` - the first parameter is 1, the second is 2, ...
    Returns:
      type the name used by the database. If the parameter type is a user-defined type, then a fully-qualified type name is returned.
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4

  - ### getParameterClassName

    String getParameterClassName(int param) throws SQLException
    Retrieves the fully-qualified name of the Java class whose instances should be passed to the method `PreparedStatement.setObject`.
    Parameters:
      `param` - the first parameter is 1, the second is 2, ...
    Returns:
      the fully-qualified name of the class in the Java programming language that would be used by the method `PreparedStatement.setObject` to set the value in the specified parameter. This is the class name used for custom mapping.
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4

  - ### getParameterMode

    int getParameterMode(int param) throws SQLException
    Retrieves the designated parameter's mode.
    Parameters:
      `param` - the first parameter is 1, the second is 2, ...
    Returns:
      mode of the parameter; one of `ParameterMetaData.parameterModeIn`, `ParameterMetaData.parameterModeOut`, or `ParameterMetaData.parameterModeInOut` `ParameterMetaData.parameterModeUnknown`.
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.4