mysql - 如何计算条件中的行数?
问题描述
我想计算所选结果的行数。
例如,SELECT * FROM TABLE1 WHERE [a (SELECT QUERY) 的行数] = 1;
解决方案
您可以使用 COUNT(*) 从表中获取计数。
SELECT * FROM TABLE1 WHERE (SELECT COUNT(*) FROM sub_table) = 1 ;
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