postgresql select return 0 when default value is set to null-CodePudding

Have the following table

create table t1(
 id SERIAL PRIMARY KEY, 
 v1 varchar(100) DEFAULT NULL,  
 v2 text
);

executing: INSERT INTO t1 (v2) VALUES ('aaaa'), ('bbb'), ('ccc'); and then SELECT * FROM t1 returns as expected:

1 |   | aaa
2 |   | bbb
3 |   | ccc

When running the following sql I'm expecting to get 1,2,3 and I get 0 rows

SELECT id FROM t1 WHERE v1=NULL also tried this SELECT id FROM t1 WHERE LENGTH(v1)=0

HOW can I get the id's Cheers

CodePudding user response：

In postgres for check value is null or not you should use below keyboard:

More details about comparison:

SELECT id FROM t1 WHERE v1 IS NULL