github
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https://github.com/simonw/datasette/issues/1671#issuecomment-1074478299 | https://api.github.com/repos/simonw/datasette/issues/1671 | 1074478299 | IC_kwDOBm6k_c5ACzzb | 9599 | 2022-03-21T22:20:26Z | 2022-03-21T22:20:26Z | OWNER | Thinking about options for fixing this... The following query works fine: ```sql select * from test_view where cast(has_expired as text) = '1' ``` I don't want to start using this for every query, because one of the goals of Datasette is to help people who are learning SQL: - #1613 If someone clicks on "View and edit SQL" from a filtered table page I don't want them to have to wonder why that `cast` is there. But... for querying views, the `cast` turns out to be necessary. So one fix would be to get the SQL generating logic to use casts like this any time it is operating against a view. An even better fix would be to detect which columns in a view come from a table and which ones might not, and only use casts for the columns that aren't definitely from a table. The trick I was exploring here might be able to help with that: - #1293 | { "total_count": 0, "+1": 0, "-1": 0, "laugh": 0, "hooray": 0, "confused": 0, "heart": 0, "rocket": 0, "eyes": 0 } |
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https://github.com/simonw/datasette/issues/1671#issuecomment-1074470568 | https://api.github.com/repos/simonw/datasette/issues/1671 | 1074470568 | IC_kwDOBm6k_c5ACx6o | 9599 | 2022-03-21T22:11:14Z | 2022-03-21T22:12:49Z | OWNER | I wonder if this will be a problem with generated columns, or with SQLite strict tables? My hunch is that strict tables will continue to work without any changes, because https://www.sqlite.org/stricttables.html says nothing about their impact on comparison operations. I should test this to make absolutely sure though. Generated columns have a type, so my hunch is they will continue to work fine too. | { "total_count": 0, "+1": 0, "-1": 0, "laugh": 0, "hooray": 0, "confused": 0, "heart": 0, "rocket": 0, "eyes": 0 } |
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https://github.com/simonw/datasette/issues/1671#issuecomment-1074468450 | https://api.github.com/repos/simonw/datasette/issues/1671 | 1074468450 | IC_kwDOBm6k_c5ACxZi | 9599 | 2022-03-21T22:08:35Z | 2022-03-21T22:10:00Z | OWNER | Relevant section of the SQLite documentation: [3.2. Affinity Of Expressions](https://www.sqlite.org/datatype3.html#affinity_of_expressions): > When an expression is a simple reference to a column of a real table (not a [VIEW](https://www.sqlite.org/lang_createview.html) or subquery) then the expression has the same affinity as the table column. In your example, `has_expired` is no longer a simple reference to a column of a real table, hence the bug. Then [4.2. Type Conversions Prior To Comparison](https://www.sqlite.org/datatype3.html#type_conversions_prior_to_comparison) fills in the rest: > SQLite may attempt to convert values between the storage classes INTEGER, REAL, and/or TEXT before performing a comparison. Whether or not any conversions are attempted before the comparison takes place depends on the type affinity of the operands. | { "total_count": 0, "+1": 0, "-1": 0, "laugh": 0, "hooray": 0, "confused": 0, "heart": 0, "rocket": 0, "eyes": 0 } |
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https://github.com/simonw/datasette/issues/1671#issuecomment-1074465536 | https://api.github.com/repos/simonw/datasette/issues/1671 | 1074465536 | IC_kwDOBm6k_c5ACwsA | 9599 | 2022-03-21T22:04:31Z | 2022-03-21T22:04:31Z | OWNER | Oh this is fascinating! I replicated the bug (thanks for the steps to reproduce) and it looks like this is down to the following: <img width="1276" alt="image" src="https://user-images.githubusercontent.com/9599/159370986-1e2fc513-6d6c-4a2f-96dd-dccf5a680fe4.png"> Against views, `where has_expired = 1` returns different results from `where has_expired = '1'` This doesn't happen against tables because of SQLite's [type affinity](https://www.sqlite.org/datatype3.html#type_affinity) mechanism, which handles the type conversion automatically. | { "total_count": 0, "+1": 0, "-1": 0, "laugh": 0, "hooray": 0, "confused": 0, "heart": 0, "rocket": 0, "eyes": 0 } |
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