concat SQL查询中的if语句

Question

我有以下SQL语句：

SELECT CONCAT(ISNULL(CONCAT(full_name,' ' ,'( ',(aff_bus) ),'('),' ) ') AS shnames,contactrecord_id 
FROM contactrecord
ORDER BY shnames ASC

我在括号中显示aff_bus列，但是如果aff_bus列为空白，我不希望使用括号。如果aff_bus列为空白，如何删除括号？

Answer 1

使用CASE检查aff_bus是否为空

SELECT 
  CASE WHEN aff_bus IS NULL THEN full_name
       WHEN aff_bus = '' THEN full_name
       ELSE CONCAT(full_name, '(', aff_bus, ')') 
       END as shshames,
  contactrecord_id
FROM contactrecord
ORDER BY shnames ASC

Answer 2

利用以下事实：将NULL与“添加”返回NULL：

SELECT ISNULL(full_name, '') + ISNULL(' ( ' + aff_bus + ' )', '') AS shnames, contactrecord_id 
FROM contactrecord
ORDER BY shnames ASC

Answer 3

1. 用例语句检查列为空还是空白。

   SELECT (CASE WHEN AFF_BUS IS NOT NULL AND AFF_BUS != '' 
            THEN  CONCAT(FULL_NAME,' ( ',aff_bus, ' ) ')
            ELSE  CONCAT (FULL_NAME,'')
        END) AS shnames, CONTACTRECORD_ID FROM CONTACTRECORD ORDER BY shnames ASC ;