PostgreSQL更新字符串，在前后添加字符

Question

帮助请用以下数据更新card_num列：

"000001"
"000002"
..
"000200"

需要这样做：

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

Answer 1

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

使用|| concatenation运算符将nulls保留为nulls而不是%,值