SQL UNION ALL 操作符：将多个 SELECT 语句的结果合并 - 详细指南

SQL UNION ALL \u662f\u4e00\u4e2a\u7528\u4e8e\u5c06\u4e24\u4e2a\u6216\u591a\u4e2a SELECT \u8bed\u53e5\u7684\u7ed3\u679c\u96c6\u5408\u5e76\u6210\u4e00\u4e2a\u7ed3\u679c\u96c6\u7684\u64cd\u4f5c\u7b26\u53f7\u3002\u5b83\u4e0e UNION \u64cd\u4f5c\u7b26\u53f7\u76f8\u4f3c\uff0c\u4f46\u4e0d\u4f1a\u53bb\u9664\u91cd\u590d\u7684\u884c\u3002\n\n\u4ee5\u4e0b\u662f\u4e00\u4e2a\u4f7f\u7528 UNION ALL \u7684\u793a\u4f8b\uff1a\n\n\nSELECT column1, column2 FROM table1\nUNION ALL\nSELECT column1, column2 FROM table2;\n\n\u8fd9\u4e2a\u8bed\u53e5\u5c06\u4f1a\u8fd4\u56de table1 \u548c table2 \u4e2d\u7684\u6240\u6709\u884c\uff0c\u5e76\u5c06\u5b83\u4eec\u5408\u5e76\u6210\u4e00\u4e2a\u7ed3\u679c\u96c6\u3002\n\n\u6ce8\u610f\uff0cUNION ALL \u4e0d\u4f1a\u53bb\u9664\u91cd\u590d\uff0c\u5982\u679c\u6709\u91cd\u590d\u7684\u884c\u5b58\u5728\uff0c\u5b83\u4eec\u90fd\u4f1a\u88ab\u5305\u542b\u5728\u7ed3\u679c\u96c6\u4e2d\u3002\u5982\u679c\u9700\u8981\u53bb\u9664\u91cd\u590d\u7684\u884c\uff0c\u53ef\u4ee5\u4f7f\u7528 UNION \u64cd\u4f5c\u7b26\u53f7\u3002