A column can be assigned a default value. When a new row is created and no values are specified for some of the columns, those columns will be filled with their respective default values. A data manipulation command can also request explicitly that a column be set to its default value, without having to know what that value is.
Details about data manipulation commands are in Chapter 6. If no default value is declared explicitly, the default value is the null value. This usually makes sense because a null value can be considered to represent unknown data.
The question is how does that work in the background? Actually the idea is quite simple. As soon as a new column with a non null default value is added to a table these columns get populated. We can see that when we check for our current table. We know that all the rows in that table should have the new default value but we know also that the table was not rewritten.
For new rows the default will be there anyway and as soon as the table is rewritten the flag is cleared:. Save my name, email, and website in this browser for the next time I comment. This site uses Akismet to reduce spam. Learn how your comment data is processed. Infrastructure at your Service. Leave a Reply Cancel Reply My comment is.. Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
Already on GitHub? Sign in to your account. The text was updated successfully, but these errors were encountered:. Sorry, something went wrong. With exact syntax in pgsql. And this is the only issue for pg well as it works perfect in mysql. And this is solved personally with such static queries but this is not the solution i was looking for. This is the perfect , applied and tested code for the type errors in QueryBuilder.
Where this makes the database independent queries.
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