您需要做的是创建一个过程，然后在该过程中声明一个 cursor 以及 variable_c_row cursor_name%ROWTYPE.

What you will need to do is create a procedure, then within the procedure declare a cursor as well as a variable_c_row cursor_name%ROWTYPE.

在程序中，这将是内容:

Within the procedure, this will be the contents:

OPEN cursor_name

FETCH cursor_name INTO variable_c_row;

WHILE cursor_name%FOUND LOOP
    -- Declare a number variable (i)
    i := 0;
    -- Declare a varchar variable (match)
    match := variable_c_row.col3
    
    WHILE length(match) > 0 LOOP OR l_countryname IS NULL
      begin
        -- Declare a yourrow%ROWTYPE variable (l_countryname)
        SELECT col4 FROM table2 INTO l_countryname WHERE col1 = match;
        
        UPDATE table1 SET col12 = l_countryname;
      exception when no_data_found then null;
      end;

      i := i+1;
      match := substr(variable_c_row.cow3, 0, length(match)-i);
    END LOOP;
  FETCH cursor_name INTO variable_c_row;
END LOOP;

CLOSE cursor_name;

由于问题没有 DDL 或 DML，我最多只能提供一个广泛的答案，尚未经过测试.

Since the question had no DDL or DML, the most I can provide is a broad answer, which has not been tested.