-----错误判断------------------------------------------------------------------------------------
SELECT
policy_jq_no,policy_sy_no,
CASE policy_jq_no
WHEN ‘‘ THEN
policy_sy_no
ELSE
policy_jq_no
END policy_no
FROM
ZY_SURVEY_VISIT order by FLOW_ID desc
---正确判断-----------------------------------------------------------------------------
SELECT
policy_jq_no,policy_sy_no,
CASE
WHEN policy_jq_no IS NULL THEN
policy_sy_no
ELSE
policy_jq_no
END policy_no
FROM
ZY_SURVEY_VISIT order by FLOW_ID desc
SQL SERVER:CASE判断空，错误一例
原文：http://www.cnblogs.com/dava/p/6416739.html
