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package java.sql;

An object that can be used to get information about the types
and properties of the columns in a ResultSet object.
The following code fragment creates the ResultSet object rs,
creates the ResultSetMetaData object rsmd, and uses rsmd
to find out how many columns rs has and whether the first column in rs
can be used in a WHERE clause.
    ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
    ResultSetMetaData rsmd = rs.getMetaData();
    int numberOfColumns = rsmd.getColumnCount();
    boolean b = rsmd.isSearchable(1);

Since:
1.1/**
 * An object that can be used to get information about the types
 * and properties of the columns in a <code>ResultSet</code> object.
 * The following code fragment creates the <code>ResultSet</code> object rs,
 * creates the <code>ResultSetMetaData</code> object rsmd, and uses rsmd
 * to find out how many columns rs has and whether the first column in rs
 * can be used in a <code>WHERE</code> clause.
 * <PRE>
 *
 *     ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
 *     ResultSetMetaData rsmd = rs.getMetaData();
 *     int numberOfColumns = rsmd.getColumnCount();
 *     boolean b = rsmd.isSearchable(1);
 *
 * </PRE>
 *
 * @since 1.1
 */

public interface ResultSetMetaData extends Wrapper {

    
Returns the number of columns in this ResultSet object.
Throws:
SQLException – if a database access error occurs
Returns:
the number of columns/**
     * Returns the number of columns in this <code>ResultSet</code> object.
     *
     * @return the number of columns
     * @exception SQLException if a database access error occurs
     */
    int getColumnCount() throws SQLException;

    
Indicates whether the designated column is automatically numbered.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
true if so; false otherwise/**
     * Indicates whether the designated column is automatically numbered.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return <code>true</code> if so; <code>false</code> otherwise
     * @exception SQLException if a database access error occurs
     */
    boolean isAutoIncrement(int column) throws SQLException;

    
Indicates whether a column's case matters.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
true if so; false otherwise/**
     * Indicates whether a column's case matters.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return <code>true</code> if so; <code>false</code> otherwise
     * @exception SQLException if a database access error occurs
     */
    boolean isCaseSensitive(int column) throws SQLException;

    
Indicates whether the designated column can be used in a where clause.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
true if so; false otherwise/**
     * Indicates whether the designated column can be used in a where clause.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return <code>true</code> if so; <code>false</code> otherwise
     * @exception SQLException if a database access error occurs
     */
    boolean isSearchable(int column) throws SQLException;

    
Indicates whether the designated column is a cash value.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
true if so; false otherwise/**
     * Indicates whether the designated column is a cash value.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return <code>true</code> if so; <code>false</code> otherwise
     * @exception SQLException if a database access error occurs
     */
    boolean isCurrency(int column) throws SQLException;

    
Indicates the nullability of values in the designated column.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
the nullability status of the given column; one of columnNoNulls,
         columnNullable or columnNullableUnknown/**
     * Indicates the nullability of values in the designated column.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return the nullability status of the given column; one of <code>columnNoNulls</code>,
     *          <code>columnNullable</code> or <code>columnNullableUnknown</code>
     * @exception SQLException if a database access error occurs
     */
    int isNullable(int column) throws SQLException;

    
The constant indicating that a
column does not allow NULL values.
/**
     * The constant indicating that a
     * column does not allow <code>NULL</code> values.
     */
    int columnNoNulls = 0;

    
The constant indicating that a
column allows NULL values.
/**
     * The constant indicating that a
     * column allows <code>NULL</code> values.
     */
    int columnNullable = 1;

    
The constant indicating that the
nullability of a column's values is unknown.
/**
     * The constant indicating that the
     * nullability of a column's values is unknown.
     */
    int columnNullableUnknown = 2;

    
Indicates whether values in the designated column are signed numbers.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
true if so; false otherwise/**
     * Indicates whether values in the designated column are signed numbers.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return <code>true</code> if so; <code>false</code> otherwise
     * @exception SQLException if a database access error occurs
     */
    boolean isSigned(int column) throws SQLException;

    
Indicates the designated column's normal maximum width in characters.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
the normal maximum number of characters allowed as the width
         of the designated column/**
     * Indicates the designated column's normal maximum width in characters.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return the normal maximum number of characters allowed as the width
     *          of the designated column
     * @exception SQLException if a database access error occurs
     */
    int getColumnDisplaySize(int column) throws SQLException;

    
Gets the designated column's suggested title for use in printouts and
displays. The suggested title is usually specified by the SQL AS
clause.  If a SQL AS is not specified, the value returned from
getColumnLabel will be the same as the value returned by the
getColumnName method.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
the suggested column title/**
     * Gets the designated column's suggested title for use in printouts and
     * displays. The suggested title is usually specified by the SQL <code>AS</code>
     * clause.  If a SQL <code>AS</code> is not specified, the value returned from
     * <code>getColumnLabel</code> will be the same as the value returned by the
     * <code>getColumnName</code> method.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return the suggested column title
     * @exception SQLException if a database access error occurs
     */
    String getColumnLabel(int column) throws SQLException;

    
Get the designated column's name.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
column name/**
     * Get the designated column's name.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return column name
     * @exception SQLException if a database access error occurs
     */
    String getColumnName(int column) throws SQLException;

    
Get the designated column's table's schema.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
schema name or "" if not applicable/**
     * Get the designated column's table's schema.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return schema name or "" if not applicable
     * @exception SQLException if a database access error occurs
     */
    String getSchemaName(int column) throws SQLException;

    
Get the designated column's specified column size.
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.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
precision/**
     * Get the designated column's specified column size.
     * 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 column the first column is 1, the second is 2, ...
     * @return precision
     * @exception SQLException if a database access error occurs
     */
    int getPrecision(int column) throws SQLException;

    
Gets the designated column's number of digits to right of the decimal point.
0 is returned for data types where the scale is not applicable.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
scale/**
     * Gets the designated column's number of digits to right of the decimal point.
     * 0 is returned for data types where the scale is not applicable.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return scale
     * @exception SQLException if a database access error occurs
     */
    int getScale(int column) throws SQLException;

    
Gets the designated column's table name.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
table name or "" if not applicable/**
     * Gets the designated column's table name.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return table name or "" if not applicable
     * @exception SQLException if a database access error occurs
     */
    String getTableName(int column) throws SQLException;

    
Gets the designated column's table's catalog name.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
the name of the catalog for the table in which the given column
         appears or "" if not applicable/**
     * Gets the designated column's table's catalog name.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return the name of the catalog for the table in which the given column
     *          appears or "" if not applicable
     * @exception SQLException if a database access error occurs
     */
    String getCatalogName(int column) throws SQLException;

    
Retrieves the designated column's SQL type.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
See Also:
Types
Returns:
SQL type from java.sql.Types/**
     * Retrieves the designated column's SQL type.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return SQL type from java.sql.Types
     * @exception SQLException if a database access error occurs
     * @see Types
     */
    int getColumnType(int column) throws SQLException;

    
Retrieves the designated column's database-specific type name.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
type name used by the database. If the column type is
a user-defined type, then a fully-qualified type name is returned./**
     * Retrieves the designated column's database-specific type name.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return type name used by the database. If the column type is
     * a user-defined type, then a fully-qualified type name is returned.
     * @exception SQLException if a database access error occurs
     */
    String getColumnTypeName(int column) throws SQLException;

    
Indicates whether the designated column is definitely not writable.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
true if so; false otherwise/**
     * Indicates whether the designated column is definitely not writable.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return <code>true</code> if so; <code>false</code> otherwise
     * @exception SQLException if a database access error occurs
     */
    boolean isReadOnly(int column) throws SQLException;

    
Indicates whether it is possible for a write on the designated column to succeed.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
true if so; false otherwise/**
     * Indicates whether it is possible for a write on the designated column to succeed.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return <code>true</code> if so; <code>false</code> otherwise
     * @exception SQLException if a database access error occurs
     */
    boolean isWritable(int column) throws SQLException;

    
Indicates whether a write on the designated column will definitely succeed.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
true if so; false otherwise/**
     * Indicates whether a write on the designated column will definitely succeed.
     *
     * @param column the first column is 1, the second is 2, ...
     * @return <code>true</code> if so; <code>false</code> otherwise
     * @exception SQLException if a database access error occurs
     */
    boolean isDefinitelyWritable(int column) throws SQLException;

    //--------------------------JDBC 2.0-----------------------------------

    
Returns the fully-qualified name of the Java class whose instances
are manufactured if the method ResultSet.getObject
is called to retrieve a value
from the column.  ResultSet.getObject may return a subclass of the
class returned by this method.
Params:
column – the first column is 1, the second is 2, ...
Throws:
SQLException – if a database access error occurs
Returns:
the fully-qualified name of the class in the Java programming
        language that would be used by the method
ResultSet.getObject to retrieve the value in the specified
column. This is the class name used for custom mapping.
Since:
1.2/**
     * <p>Returns the fully-qualified name of the Java class whose instances
     * are manufactured if the method <code>ResultSet.getObject</code>
     * is called to retrieve a value
     * from the column.  <code>ResultSet.getObject</code> may return a subclass of the
     * class returned by this method.
     *
     * @param column the first column 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>ResultSet.getObject</code> to retrieve the value in the specified
     * column. This is the class name used for custom mapping.
     * @exception SQLException if a database access error occurs
     * @since 1.2
     */
    String getColumnClassName(int column) throws SQLException;
}