#29222: Substr on NULL values returns incorrect results with pattern lookups.
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Reporter: felixxm | Owner: nobody
Type: Bug | Status: new
Component: Database | Version: master
layer (models, ORM) |
Severity: Normal | Keywords: Oracle
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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feb683c4c2c5ecfb61e4cb490c3e357450c0c0e8 revealed an unrelated issue on
Oracle. `SUBSTR(NULL, x, y)` returns `NULL` on Oracle which can be
concatenate with other strings, hence if we use it with pattern lookups
then all rows match an query, e.g.
- `__startswith=Substr(sth, x, y)` -> `LIKE SUBSTR(sth, x, y) || '%'` ->
`LIKE '%'`,
- `__endswith=Substr(sth, x, y)` -> `LIKE '%' || SUBSTR(sth, x, y)` ->
`LIKE '%'`,
- `__contains=Substr(sth, x, y)` -> `LIKE '%' || SUBSTR(sth, x, y) || '%'
` -> `LIKE '%%'`,
which is unexpected.
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Ticket URL: <https://code.djangoproject.com/ticket/29222>
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