oracle explain怎么用 oracle有explain语句吗
oracle\u7684Explain Plan\u5982\u4f55\u9605\u8bfbexplain plan for select * from table;
select * from table(dbms_xplan.display); \u4f60\u8bf4\u7684\u662f\u8fd9\u4e2a\u5417\uff1f
\u8fd9\u6837\u751f\u6210\u7684\u6267\u884c\u8ba1\u5212\u770b\u4e86\u4e5f\u662f\u767d\u770b\uff0c\u56e0\u4e3aexplain plan for \u662f\u4e0d\u80fd\u5bf9sql\u8bed\u53e5\u4e2d\u7684\u7ed1\u5b9a\u53d8\u91cf\u8fdb\u884c\u7aa5\u6d4b\u7684\uff0c\u751f\u6210\u7684\u6267\u884c\u8ba1\u5212\u4e5f\u662f\u4e0d\u51c6\u786e\u7684\u3002\u751f\u4ea7\u4e2d\u5927\u90e8\u5206sql\u90fd\u662f\u4f7f\u7528\u7ed1\u5b9a\u53d8\u91cf\u7684\u3002
\u7b80\u5355\u7684\u67e5\u8be2\u8868\u91cc\u6240\u6709\u4fe1\u606f. select Statement \u67e5\u8be2\u8bed\u53e5.
\u76ee\u6807\u6240\u6709\u884c (\u6ee1\u8db3\u6761\u4ef6\u7684\u6240\u6709\u884c)\u67e5\u8be2\u7684\u65b9\u5f0f\u662f\u904d\u5386\u5168\u8868return all rows from a table \u6d89\u53ca\u5230726\u884c\u7684\u6570\u636e\uff01
如果定义了一系列表格,选择性是指在合并以任何顺序满足所有可用判断的全部表格后,所得结果中的行部分。
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