请问 SQL 跟新大量数据怎么处理快呢？

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This topic created in 1212 days ago, the information mentioned may be changed or developed.

类似这样子查询跟新

UPDATE T_ T SET T.KCXZ =(SELECT tcz.KCXZ FROM T_J20230106 tcz WHERE T.ID=tcz.ID AND T.KCXZ!=tcz.KCXZ) WHERE 1=1

6 replies • 2023-01-12 12:30:14 +08:00

512357301

Jan 11, 2023 via Android

更

fackVL

Jan 11, 2023 via iPhone

更新

yushiro

Jan 11, 2023 via iPhone

你先写 select 语句，用 join 的方式把待修改的数据取出来，然后再把 from 前面的代码改为 update 表名 set xxx

zhangzhiming

Jan 11, 2023 via iPhone

@yushiro 我是全表更新，这样很慢

n0099

Jan 11, 2023

看看 EXPLAIN SELECT tcz.KCXZ FROM T_J20230106 tcz WHERE T.ID=tcz.ID AND T.KCXZ!=tcz.KCXZ 是不是 full table scan

yushiro

Jan 12, 2023 via iPhone

@hemingyang 表的数据量有多少？上千万？