您要添加 UNIQUE

code>约束到你的表。如果您单独写入 UNIQUE 约束，则更清楚如何将其应用于列的任意组合。

  CREATE TABLE table_name（
 subject1 VARCHAR（30），
 subject2 VARCHAR（30），
 subject3 VARCHAR（30），
 UNIQUE（subject1 ，subject2，subject3）
）; 
 

How would I insert multiple rows or values and avoid duplicates in the following schema.

table schema is

id,subject1,subject2,subject3

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") 

In the table let's say I already have a record for

id,subject1,subject2,subject3
1,"cats", "dogs", "hamsters"

so I want it to just insert

VALUES ("squirrels", "badgers", "minxes")  
VALUES ("moose", "deer", "ocelots")

I've seen answers about avoiding duplicates for single items, but not for 3.

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)
);