SQL Server 2017 (Linux)

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CREATE TABLE T226714 (
    code_type CHAR(4) NOT NULL,
    code VARCHAR(30) NOT NULL,
    code_len AS len(code + 'X') - 1 
);

CREATE UNIQUE INDEX UI ON T226714 (code_type, code, code_len);
-- works
INSERT INTO T226714 VALUES ('cha', ' ');
INSERT INTO T226714 VALUES ('cha', '');
2 rows affected

-- can't insert this as a third row due to the unique index:
INSERT INTO T226714 VALUES ('cha', ' ');
Msg 2601 Level 14 State 1 Line 2
Cannot insert duplicate key row in object 'dbo.T226714' with unique index 'UI'. The duplicate key value is (cha ,  , 1).
Msg 3621 Level 0 State 0 Line 2
The statement has been terminated.

-- can't insert this as a third row due to the unique index:
INSERT INTO T226714 VALUES ('cha', '');
Msg 2601 Level 14 State 1 Line 2
Cannot insert duplicate key row in object 'dbo.T226714' with unique index 'UI'. The duplicate key value is (cha , , 0).
Msg 3621 Level 0 State 0 Line 2
The statement has been terminated.

select * from T226714 ;


code_type
code
code_len


cha

0

cha
 
1