修改“在子程序里声明变量和常量并赋值”章节示例中 p_name 的类型，使用 ware.w_name%type 代替 varchar。

delimiter /
CREATE OR REPLACE PACKAGE pkg_ware_mgmt as
    MAX_WARES           constant number(2,0) := 10;
    MAX_DISTS_PER_WARE  constant number(2,0) := 10;
    FUNCTION  f_check_ware_exists(p_name IN ware.w_name%TYPE) RETURN BOOLEAN ;
END;
/
delimiter ;
delimiter /
CREATE OR REPLACE PACKAGE BODY pkg_ware_mgmt as
    FUNCTION f_check_ware_exists( p_name IN ware.w_name%TYPE ) RETURN BOOLEAN
    IS
        i_cnt   number := -1;
        b_ret   boolean := FALSE;
    BEGIN
        SELECT count(*) INTO i_cnt FROM ware WHERE w_name = p_name AND rownum < 2;
        b_ret := (i_cnt = 1);
        RETURN b_ret;
    EXCEPTION
        WHEN OTHERS THEN            
            RETURN FALSE;
    END;
END; 
/
delimiter ;
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