多表更新：参照另外的表来更新本表的内容
table_reference
{[inner | cross] join | {left | right} [outer] join} 内连接、左外连接、右外连接
table_reference
ON conditional_expr 表的连接条件
update table_references
SET col_name1={expr1 | default}
[ , col_name={expr2={expr2 | default }}]......
[ where where_condition]
update tdb_goods inner join tdb_goods_cates on goods_cate=cate_name set goods_cate =cate_id;