mysql>EXPLAINSELECTp.*->FROMparent p->WHEREp.idNOTIN(SELECTc.parent_idFROMchild c)\G*********************1. row***********************id:1selecttype:PRIMARYtable: p type:ALLpossible_keys:NULLkey:NULLkey_len:NULL
-> FROM (SELECT id FROM users WHERE first = ‘west’) c; 4. DEPENDENT SUBQUERY 这个select-type 值是为使用子查询而定义的。下面的SQL语句提供了这个值: mysql> EXPLAIN SELECT p.* -> FROM parent p -> WHERE p.id NOT IN (SELECT c.parent_id FROM child c); 5. UNION 这是UNION 语句其中...
select_type: DEPENDENT SUBQUERY table: c type: index_subquery possible_keys: parent_id key: parent_id key_len: 4 ref: func rows: 1 Extra: Using index 2 rows in set (0.00 sec) EXPLAIN SELECT p.* FROM parent p LEFT JOIN child c ON = c.parent_id WHERE c.child_id IS NULL\G **...
The lung architecture of different inbred strains of mice is highly variable. However, little is known about the lung gene expression differences that lead to this strain variation. In this study, gene expression profiles from the lungs of C3H/HeJ (C3), C57BL/6J (B6) and A/J mice as ...
Open the Command Palette (Ctrl+Shift+P on Windows or Cmd+Shift+P on Mac) and open the editor for c_cpp_properties.json by running: `C/C++: Edit Configurations (JSON)` Confirm you’re using a recursive path ending in /** under “includePath”: ...
可以参考MySQL Reference Manual 获得更多信息:http://dev.mysql.com/doc/refman/5.5/en/explain-output.html。 2.1 key key 列指出优化器选择使用的索引。一般来说SQL 查询中的每个表都仅使用一个索引。也存在索引合并的少数例外情况,如给定表上用到了两个或者更多索引。
(x-axis) depending on the type of change (y-axis) for both groups. The factor has a significant effect on the segmentation probability if the confidence interval does not include 1 (dashed line). Figure part (c) shows the density (y-axis) of the mean event length in seconds (x-axis...
Understanding the relationship between urban form and structure and spatial inequality of property flood risk has been a longstanding challenge in urban planning and emergency management. Here we explore eight urban form and structure features to explain
In this analysis, the willingness to provide flexibility in electricity consumption serves as the dependent variable in the regression model, which is to be explained by the same set of independent and control variables as in the analysis of the willingness to adopt time-variant electricity tariffs...
可以参考MySQL Reference Manual 获得更多信息:http://dev.mysql.com/doc/refman/5.5/en/explain-output.html。 2.1 key key 列指出优化器选择使用的索引。一般来说SQL 查询中的每个表都仅使用一个索引。也存在索引合并的少数例外情况,如给定表上用到了两个或者更多索引。