[5.4] Add an unsignedDecimal method to Laravel Schema Blueprint

[phpguru]

… along with a unit test for it. Improves solution offered to Issue 875.

[tillkruss]

Did you test that on MySQL, PostgreSQL and SqlServer?

[sisve]

It will not work on PostgreSQL and SQL Server because they follow the sql standard, and there's no such thing as unsigned numerics. If you want to force non-negative values you use constraints, not data types.

Exact numeric types hold numeric values without digits after the decimal or with a firm number of digits after the decimal. All exact numeric types are signed.

Source: https://en.wikibooks.org/wiki/Structured_Query_Language/Data_Types#Exact_Numeric

Approximate numeric types hold numeric values with an implementation defined precision (after the decimal). All approximate numeric types are signed. Their primary use cases are scientific computations.

Source: https://en.wikibooks.org/wiki/Structured_Query_Language/Data_Types#Approximate_Numeric

All the data types in PostgreSQL: Documentation: 9.5: Data Types are signed,
there are no unsigned versions.

On the other hand, this PR makes sense to bring consistency to the schema builder api even if the underlying database doesn't support the result.

[phpguru]

Did you test that on MySQL, PostgreSQL and SqlServer?

I did not test on PostgreSQL nor SqlServer, however I did test with the new PHPunit test provided with this PR and verified it passes the test and verified the code works against MySQL.

this PR makes sense to bring consistency to the schema builder api even if the
underlying database doesn't support the result.

That was my thought as well. The "unsigned[NumericType]" methods are convenience wrappers. I've merely added one that seemed oddly missing.

[tillkruss]

@sisve thanks.

[ziming]

In MySQL 8.0.17

https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-17.html

"The UNSIGNED attribute is deprecated for columns of type FLOAT, DOUBLE, and DECIMAL (and any synonyms) and support for it will be removed in a future MySQL version. Consider using a simple CHECK constraint instead for such columns."