下面的两个查询中,哪个对 postgresql 来说最有效?并且在可读性等方面具有更好的风格。
区别在于语句的位置doctor.type != 'surgeon'
在 WHERE 子句中:
SELECT practice.name, doctor.name
FROM doctor
JOIN practice ON (doctor_code = code)
WHERE doctor.name LIKE '%son'
AND (doctor.type != 'surgeon');
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或者在 JOIN 子句中:
SELECT practice.name, doctor.name
FROM doctor
JOIN practice ON (doctor_code = code AND doctor.type != 'surgeon')
WHERE doctor.name LIKE '%son';
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