摘要：
count（字段）不会取Null的 select count(*) from test01 7条 select count(0) from test01 7条 select count(a) from test01 7条 select count(b) from test01 6条 阅读全文
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摘要：
count（字段）不会取Null的 select count(*) from test01 7条 select count(0) from test01 7条 select count(a) from test01 7条 select count(b) from test01 6条 阅读全文
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