Improve error message when column doesn't have default

[NiwakaDev]

What type of enhancement is this?

User experience

What does the enhancement do?

Improve an error message when a column doesn't have default.

Let's say that we have the following table:

create table test_table(a string not null, ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP);

And then, The following sql:

insert into test_table values(default, default);

results in:

ERROR 1815 (HY000): Failed to execute query, query: insert into test_table values(default, default)

This error doesn't tell us that the a doesn't have default.

I think that we can improve the error message like this:

`a` doesn't have a default value

Implementation challenges

No response

[evenyag]

I guess the server doesn't return the root cause due to #2428

ERROR 1815 (HY000): Failed to execute query, query: insert into test_table values(default, default)

After #2506 is merged, the latest commit should output the reason

mysql> insert into test_table values(default, default);
ERROR 1815 (HY000): No valid default value can be built automatically, column: a

[NiwakaDev]

I see. Thank you.