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323 | 323 | # gender_by_name |
324 | 324 |
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325 | 325 | http://ceur-ws.org/Vol-2754/paper3.pdf |
326 | | - |
327 | | -# Тонкости сравнения NULL и record |
328 | | - |
329 | | -Нужно об этом знать, чтобы на напороться на ошибки в своём коде. |
330 | | -Testing a ROW expression with IS NULL only reports TRUE if every single column is NULL |
331 | | -```sql |
332 | | -SELECT |
333 | | - (NULL, NULL) IS NULL as "(NULL, NULL) IS NULL", --true |
334 | | - (NULL, NULL) IS NOT NULL as "(NULL, NULL) IS NOT NULL", --false |
335 | | - NOT (NULL, NULL) IS NULL as "NOT (NULL, NULL) IS NULL", --false |
336 | | - |
337 | | - (1, NULL) IS NULL as "(1, NULL) IS NULL", --false |
338 | | - (1, NULL) IS NOT NULL as "(1, NULL) IS NOT NULL", --false --!!! |
339 | | - NOT (1, NULL) IS NULL as "NOT (1, NULL) IS NULL" --true --!!! |
340 | | -``` |
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