docs: clarify nullable override behavior

[andrewmbenton]

• also remove some dead code

[daison12006013]

@andrewmbenton is there a documentation as well if we can re-use a certain override block in sqlc.yaml?

overrides: go: overrides: - column: "profiles.payment_flag" - column: "profileviews.is_active_member" - column: "profileviews.is_active_profile" nullable: true go_type: import: "gopkg.in/guregu/null.v4" package: "null" type: "Bool" - db_type: "varchar" - db_type: "text" - db_type: "json" nullable: true go_type: import: "gopkg.in/guregu/null.v4" package: "null" type: "String"

As an example above, where in the 3 columns will have a null.Bool.

Meanwhile I am using anchors, somewhat like this

 # Boolean specific columns - column: "profiles.payment_flag" nullable: true go_type: &nullBoolean import: "gopkg.in/guregu/null.v4" package: "null" type: "Bool" - column: "profileviews.is_active_member" nullable: true go_type: *nullBoolean - column: "profileviews.is_active_profile" nullable: true go_type: *nullBoolean # String - db_type: "varchar" nullable: true go_type: &nullString import: "gopkg.in/guregu/null.v4" package: "null" type: "String" - db_type: "text" nullable: true go_type: *nullString - db_type: "json" nullable: true go_type: *nullString

[andrewmbenton]

As an example above, where in the 3 columns will have a null.Bool.

This "fallthrough" behavior won't work as far as I know, although I think it is technically possible to implement. The anchors solution seems like the best way to reduce redundancy at the moment.