你能解释一下COALESCE吗? [英] Can you please explain COALESCE
问题描述
你能解释一下这个吗?
我尝试了什么:
REPLACE(
REPLACE(
REPLACE(
COALESCE(NULLIF(LTRIM(RTRIM(Preferred_Address_Line_1)),''),' ')+''
+ COALESCE(NULLIF(LTRIM(RTRIM(Preferred_Address_Line_2)),''),'')+''
+ COALESCE(NULLIF(LTRIM) (RTRIM(Preferred_Address_Line_3)),''),'')+''
,'',''+ CHAR(7)),CHAR(7)+'',''), CHAR(7),'')))AS ADDRESS,
Could you please explain this ?
What I have tried:
REPLACE(
REPLACE(
REPLACE(
COALESCE (NULLIF (LTRIM(RTRIM( Preferred_Address_Line_1 )), ''), ' ')+' '
+COALESCE (NULLIF (LTRIM(RTRIM( Preferred_Address_Line_2 )), ''), ' ')+' '
+COALESCE (NULLIF (LTRIM(RTRIM( Preferred_Address_Line_3 )), ''), ' ')+' '
,' ',' '+CHAR(7)),CHAR(7)+' ',''),CHAR(7),'') ))AS ADDRESS,
推荐答案
如何读取有关COALESCE的文档 [ ^ ]。
How about reading the documentation on COALESCE[^].
评估按顺序测试参数并返回最初未计算为NULL的第一个表达式的当前值。
Evaluates the arguments in order and returns the current value of the first expression that initially does not evaluate to NULL.
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