// ---------------------------------------------------------------------------
 
// psrse : ALTER TABLE dbo.hlist ADD CONSTRAINT FK_hlist_history FOREIGN KEY (id) REFERENCES dbo.history(ID)

bool extract_alter_fk( String sql_cmd, String &slave_table, String &slave_field, String &master_table, String &master_field )
{
    sql_cmd = sql_cmd.Trim().LowerCase();
    String right_part = sql_cmd;
     TVMRegEx re;
     re <<  "alter[' ']+table[' ']+[dbo.]+" ;;
     if( !re.Search(sql_cmd, true))
        return false;
    right_part = re.Match[ 2 ];

    String shablon_table =  "[a-z,'_']\\w+" ;
    re.Clear();
    re << shablon_table;;
    if( !re.Search(right_part, true) )
        return false;
    slave_table = re.Match[ 1 ];
    right_part = re.Match[ 2 ];

    re.Clear();
    re <<   "foreign[' ']+key " ;
    if( !re.Search(right_part, true) )
        return false;
    right_part = re.Match[ 2 ];

    re.Clear();
    String shablon_field =  "[a-z,'_']\\w+" ;
    re << shablon_field;
    if( !re.Search(right_part, true) )
        return false;
    slave_field = re.Match[ 1 ];
    right_part = re.Match[ 2 ];

    re.Clear();
    re <<  "references " ;
    if( !re.Search(right_part, true) )
        return false;
    right_part = re.Match[ 2 ];

    re.Clear();
    re <<  "\\.+[a-z,'_']\\w+" ;
    if( !re.Search(right_part, true) )
        return false;
    master_table = re.Match[ 1 ]; master_table = (( master_table[ 1 ]=='.')? master_table.SubString( 2 , master_table.Length()) : master_table);
    right_part = re.Match[ 2 ];

    re.Clear();
    re << shablon_field;
    if( !re.Search(right_part, true) )
        return false;
    master_field = re.Match[ 1 ];
    return !master_field.IsEmpty();
}