Oracle Data table fields turn uppercase lowercase

 1 BEGIN
 2     FOR c IN ( SELECT COLUMN_NAME cn FROM all_tab_columns WHERE table_name = '表名' )
 3     loop
 4 BEGIN
 5     execute IMMEDIATE 'alter table 表名 rename column "' || c.cn || '" to ' || c.cn;
 6 EXCEPTION 
 7     WHEN others THEN
 8     dbms_output.put_line ( '表名' ||  ' . '  || c.cn ||  ' already exists ' );
 . 9  
10  the END ;
 . 11  
12 is  the END Loop;
 13 is  the END ;