高效统计
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如何高效统计MySQL中多张表的数据条数?
要统计MySQL中多张表的数据条数,可以使用UNION ALL将多个COUNT(*)查询结果合并起来。以下是一个示例:,,“sql,SELECT ‘table1’ AS table_name, COUNT(*) AS count FROM table1,UNION ALL,SELECT ‘table2’ AS table_name, COUNT(*) AS count FROM table2,UNION ALL,SELECT ‘table3’ AS table_name, COUNT(*) AS count FROM table3;,`,,这个查询将分别计算table1、table2和table3`的数据条数,并将结果合并成一个新的结果集。