Postgresql更新字符串，前后添加字符

Question

请帮助使用以下数据更新列 card_num：

"000001"
"000002"
..
"000200"

需要做：

"%000001,"
"%000002,"
..
"%000200,"

Answer 1

update table set card_num = '%'||card_num||','

使用|| 串联运算符留下nullsas nulls，而不是%,值