有兩個表
表a
chejia chudeng
LBERCACB7DX4 '2013-08-27 00:00:00'
LSVFK46R5D2 '2013-10-16 00:00:00'
LSVFK46R5D2 null
LZWACAGA7A '2010-09-02 00:00:00'
LLV2A2A196 null
LVGBE40K7A '2011-03-24 00:00:00'
LSGSA52S2CY '2012-01-09 00:00:00'
LJDLAA296CO '2012-09-20 00:00:00'
LGBG22E09 null
LGBG22E099 '2009-11-28 00:00:00'
表 b
chejia riqi
LBERCACB7DX4 '2013-08-27 00:00:00'
LSVFK46R5D2 '2013-10-16 00:00:00'
LSVFK46R5D2 '2013-10-16 00:00:00'
LZWACAGA7A '2010-09-02 00:00:00'
LLV2A2A196 '2007-04-05 00:00:00'
LVGBE40K7A '2011-03-24 00:00:00'
LSGSA52S2CY '2012-01-09 00:00:00'
LJDLAA296CO '2012-09-20 00:00:00'
LGBG22E09 '2009-11-28 00:00:00'
LGBG22E099 '2009-11-28 00:00:00'
表B中有與表a相同的欄位chejia,riqi,
想用B中的日期更新到A中chejia相同的riqi中，但是只更新null的部分，不為null的部分不更新。
uj5u.com熱心網友回復：
update a, b set a.riqi=b.riqi where a.chejia=b.chejia and a.riqi s null
uj5u.com熱心網友回復：
update a,b set a.riqi=b.riqi where a.chejia=b.chenjia and a.riqi is null轉載請註明出處，本文鏈接：https://www.uj5u.com/shujuku/99593.html
標籤：MySQL
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