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Oracle unique index

2022-04-22 07:47:00 【A constant stream of cars】

 

by NULL A unique index can be set for the field

1： Multiple fields are NULL The record of , It can be inserted into the database normally

2： Duplicate value insertion will check the duplicate value normally

Tips: Set string null It also checks for duplicate values

test 3770 strip NULL Worth recording , A valuable record . Query the value of this field separately , Can hit the index query

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