sql中存储过程的嵌套循环不起作用

CREATE PROCEDURE nested_loop_example
AS
BEGIN
    DECLARE @outer_value INT;
    DECLARE @inner_value INT;
    
    -- Outer loop
    DECLARE outer_cursor CURSOR FOR
    SELECT column_name FROM table_name;
    
    OPEN outer_cursor;
    FETCH NEXT FROM outer_cursor INTO @outer_value;
    
    WHILE @@FETCH_STATUS = 0
    BEGIN
        -- Inner loop
        DECLARE inner_cursor CURSOR FOR
        SELECT column_name FROM table_name;
        
        OPEN inner_cursor;
        FETCH NEXT FROM inner_cursor INTO @inner_value;
        
        WHILE @@FETCH_STATUS = 0
        BEGIN
            -- Perform operations using @outer_value and @inner_value
            
            FETCH NEXT FROM inner_cursor INTO @inner_value;
        END
        
        CLOSE inner_cursor;
        DEALLOCATE inner_cursor;
        
        FETCH NEXT FROM outer_cursor INTO @outer_value;
    END
    
    CLOSE outer_cursor;
    DEALLOCATE outer_cursor;
END