问题描述
如何在以下架构中插入多行或值并避免重复.
How would I insert multiple rows or values and avoid duplicates in the following schema.
表架构是
id,subject1,subject2,subject3
id 会自动递增.
重复将是所有 subject1、subject2、subject3 已经以完全相同的顺序存在于记录中.
id is auto incremented.
A duplicate would be where all subject1,subject2,subject3 already exist in a record in the exact same order.
INSERT INTO "table_name" ("subject1","subject2","subject3")
VALUES ("cats", "dogs", "hamsters")
VALUES ("squirrels", "badgers", "minxes")
VALUES ("moose", "deer", "ocelots")
在表格中假设我已经有记录
In the table let's say I already have a record for
id,subject1,subject2,subject3
1,"cats", "dogs", "hamsters"
所以我希望它只插入
VALUES ("squirrels", "badgers", "minxes")
VALUES ("moose", "deer", "ocelots")
我已经看到有关避免单个项目重复的答案，但不是 3.
I've seen answers about avoiding duplicates for single items, but not for 3.
推荐答案
您想将 UNIQUE 约束添加到您的表中.如果您单独编写 UNIQUE 约束，如何将其应用于列的任意组合会变得更加清晰.
You want to add the UNIQUE constraint to your table. If you write the UNIQUE constraint out separately, it becomes clearer how to apply it to arbitrary combinations of columns.
CREATE TABLE table_name (
subject1 VARCHAR(30),
subject2 VARCHAR(30),
subject3 VARCHAR(30),
UNIQUE (subject1, subject2, subject3)
);
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