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Oracle??Nulls?????????

?Oracle???????????????????????????Null???Nulls?????????????Null?????????????????????????????????Null???????????????????????

Nulls First?Nulls Last???

Oracle?????Nulls?????NULLS FIRST?NULLS LAST?????????????Null?????NULLS FIRST??Null??????????NULLS LAST???Null?????????

Nulls First???

???????NULLS FIRST??????

SELECT * FROM zl_cbqc ORDER BY cb_ld NULLS FIRST;

???????cb_ld??????????cb_ld????Null????Null????????????????cb_ld???????

• 1
• Null
• 3

?????????????

Nulls Last???

????Null?????????????NULLS LAST?????????

SELECT * FROM zl_cbqc ORDER BY cb_ld NULLS LAST;

??????????????????

SQL WITH???????

????????Nulls??????????WITH???????????????????WITH????????

WITH tab AS (    SELECT 1 id, 'Name1' name, 'Dept1' dept FROM dual    UNION ALL    SELECT 2 id, 'Name2' name, 'Dept2' dept FROM dual    UNION ALL    SELECT 3 id, 'Name3' name, 'Dept3' dept FROM dual    UNION ALL    SELECT 4 id, 'Name4' name, 'Dept4' dept FROM dual)SELECT id, name, dept FROM tab ORDER BY dept, id NULLS LAST;

???????dept?id??????????NULLS LAST???dept???????id???????????????dept????Null????????????????

??????Null??

???????Null???????????????????????????????NULLS FIRST???????????????????????????????????Null????????NULLS LAST??????

??

Oracle?NULLS FIRST?NULLS LAST????????????????????????????????Null???????????????????????