Postgresql invalid input syntax for type boolean: "null"

Question

I' learning postgresql, and I typed the following commands.

 CREATE TABLE t(co1 boolean, col2 text);
 INSERT INTO t VALUES(NULL, 'NULL');
 SELECT * FROM t where col2::boolean;

And the result came out like this:

ERROR:  invalid input syntax for type boolean: "NULL".

Why is that happened since things like 'True'::boolean is correct?

I tried transforming data from text to boolean. 'True'::boolean has no error, but 'Null'::boolean return an error. — C-Entropy
– C-Entropy, Commented Aug 14, 2018 at 12:59

Fahmi · Accepted Answer · 2018-08-14 12:15:11Z

2

Your col2 column is text, not boolean

CREATE TABLE t(co1 boolean, col2 text);
 INSERT INTO t VALUES(NULL, 'NULL');
 SELECT * FROM t where col2::text;

answered Aug 14, 2018 at 12:15

Fahmi

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