src/java.sql/share/classes/java/sql/ParameterMetaData.java

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package java.sql;

/**
 * An object that can be used to get information about the types
 * and properties for each parameter marker in a
 * {@code PreparedStatement} object. For some queries and driver
 * implementations, the data that would be returned by a {@code ParameterMetaData}
 * object may not be available until the {@code PreparedStatement} has
 * been executed.
 *<p>
 *Some driver implementations may not be able to provide information about the
 *types and properties for each parameter marker in a {@code CallableStatement}
 *object.
 *
 * @since 1.4
 */

public interface ParameterMetaData extends Wrapper {

    /**
     * Retrieves the number of parameters in the {@code PreparedStatement}
     * object for which this {@code ParameterMetaData} object contains
     * information.
     *
     * @return the number of parameters
     * @throws SQLException if a database access error occurs
     * @since 1.4
     */
    int getParameterCount() throws SQLException;

    /**
     * Retrieves whether null values are allowed in the designated parameter.
     *
     * @param param the first parameter is 1, the second is 2, ...
     * @return the nullability status of the given parameter; one of
     *        {@code ParameterMetaData.parameterNoNulls},
     *        {@code ParameterMetaData.parameterNullable}, or
     *        {@code ParameterMetaData.parameterNullableUnknown}
     * @throws SQLException if a database access error occurs
     * @since 1.4
     */
    int isNullable(int param) throws SQLException;

    /**
     * The constant indicating that a
     * parameter will not allow {@code NULL} values.
     */
    int parameterNoNulls = 0;

    /**
     * The constant indicating that a
     * parameter will allow {@code NULL} values.
     */
    int parameterNullable = 1;

    /**
     * The constant indicating that the
     * nullability of a parameter is unknown.
     */
    int parameterNullableUnknown = 2;

    /**
     * Retrieves whether values for the designated parameter can be signed numbers.
     *
     * @param param the first parameter is 1, the second is 2, ...
     * @return {@code true} if so; {@code false} otherwise
     * @throws SQLException if a database access error occurs
     * @since 1.4
     */
    boolean isSigned(int param) throws SQLException;

    /**
     * Retrieves the designated parameter's specified column size.
     *
     * <P>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.
     *
     * @param param the first parameter is 1, the second is 2, ...
     * @return precision
     * @throws SQLException if a database access error occurs
     * @since 1.4
     */
    int getPrecision(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.
     *
     * @param param the first parameter is 1, the second is 2, ...
     * @return scale
     * @throws SQLException if a database access error occurs
     * @since 1.4
     */
    int getScale(int param) throws SQLException;

    /**
     * Retrieves the designated parameter's SQL type.
     *
     * @param param the first parameter is 1, the second is 2, ...
     * @return SQL type from {@code java.sql.Types}
     * @throws SQLException if a database access error occurs
     * @since 1.4
     * @see Types
     */
    int getParameterType(int param) throws SQLException;

    /**
     * Retrieves the designated parameter's database-specific type name.
     *
     * @param param the first parameter is 1, the second is 2, ...
     * @return 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
     */
    String getParameterTypeName(int param) throws SQLException;


    /**
     * Retrieves the fully-qualified name of the Java class whose instances
     * should be passed to the method {@code PreparedStatement.setObject}.
     *
     * @param param the first parameter is 1, the second is 2, ...
     * @return the fully-qualified name of the class in the Java programming
     *         language that would be used by the method
     *         {@code 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
     */
    String getParameterClassName(int param) throws SQLException;

    /**
     * The constant indicating that the mode of the parameter is unknown.
     */
    int parameterModeUnknown = 0;

    /**
     * The constant indicating that the parameter's mode is IN.
     */
    int parameterModeIn = 1;

    /**
     * The constant indicating that the parameter's mode is INOUT.
     */
    int parameterModeInOut = 2;

    /**
     * The constant indicating that the parameter's mode is  OUT.
     */
    int parameterModeOut = 4;

    /**
     * Retrieves the designated parameter's mode.
     *
     * @param param the first parameter is 1, the second is 2, ...
     * @return mode of the parameter; one of
     *        {@code ParameterMetaData.parameterModeIn},
     *        {@code ParameterMetaData.parameterModeOut}, or
     *        {@code ParameterMetaData.parameterModeInOut}
     *        {@code ParameterMetaData.parameterModeUnknown}.
     * @throws SQLException if a database access error occurs
     * @since 1.4
     */
    int getParameterMode(int param) throws SQLException;
}