mysql数据库汉字转拼音

CREATE FUNCTION chinese_to_pinyin(str VARCHAR(255)) RETURNS VARCHAR(255)
BEGIN
  DECLARE pinyin VARCHAR(255);
  DECLARE result VARCHAR(255);
  DECLARE i INT DEFAULT 1;

  SET pinyin = 'a,a,a,a,a,a,a,b,b,b,b,c,c,c,c,d,d,d,d,d,e,e,e,e,e,e,e,e,e,e,f,f,f,f,g,g,g,g,h,h,h,h,h,j,j,j,j,k,k,k,k,l,l,l,l,l,l,m,m,m,m,n,n,n,n,n,n,n,o,o,o,o,o,o,o,p,p,p,p,q,q,q,q,r,r,r,r,r,r,r,s,s,s,s,s,s,s,s,t,t,t,t,t,t,t,t,t,t,t,w,w,w,w,x,x,x,x,y,y,y,y,y