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當一週內沒有找到數據時,SQL將返回1.如何使它返回0?SQL按周生成系列,如果沒有找到,則返回0
SELECT w.week, COUNT(*) AS total
FROM (SELECT generate_series(min(DATE_TRUNC('week', created_at)),
max(DATE_TRUNC('week', created_at)),
interval '7 day'
) as week
FROM reviews
) w LEFT JOIN
"reviews"
ON DATE_TRUNC('week', created_at) = w.week
GROUP BY w.week
ORDER BY w.week;
你有外連接,所以'COUNT(*)'來'計數(評論。*)'應做的伎倆 –