使用 UPDATE 语句修改表中的字段值。 示例如下： 创建示例表 t1 和 t2 。 obclient > CREATE TABLE t1 ( c1 int primary key , c2 int ); Query OK , 0 rows affected ( 0.16 sec ) obclient > INS...

MINUS Description Syntax Examples MINUS Description MINUS compares the result of two queries and returns the different rows in the first query that are not output by ...

Explain Statements That Use Joins Index Join Variations of Index Join Configuration Hash Join Runtime Statistics Configuration Related optimizations Merge Join Explain S...

Explain Statements That Use Joins Index Join Variations of Index Join Configuration Hash Join Runtime Statistics Configuration Merge Join Explain Statements That Use Join...

一级分区裁剪的基本原理 二级分区裁剪的基本原理 当用户访问分区表时，往往只需要访问其中部分的分区，所以通过优化器避免访问无关分区的优化过程我们称之为分区裁剪（(Partition Pruning）。分区裁剪是分区表提供的重要优化手段，通过分区的裁剪，SQL 的执行效率可以得到大幅度的提升。您可以利用分区裁剪的特性，在访问中加入定位分区的条件，避免访问无...

WEEKDAY() Description Syntax Arguments Examples WEEKDAY() Description Returns the weekday index for date (0 = Monday, 1 = Tuesday, … 6 = Sunday). Returns NULL if da...

Decorrelation of Correlated Subquery Introduction Restrictions Example Decorrelation of Correlated Subquery Subquery related optimizations describes how TiDB handles subquer...

DROP [GLOBAL|SESSION] BINDING Synopsis Examples MySQL compatibility See also DROP [GLOBAL|SESSION] BINDING This statement removes a binding from a specific SQL statement. Bi...

DROP [GLOBAL|SESSION] BINDING Synopsis Examples MySQL compatibility See also DROP [GLOBAL|SESSION] BINDING This statement removes a binding from a specific SQL statement. Bi...

SORT 的算法 普通排序 前缀排序 TOP-N 排序 其他 SORT 算子的消除 SORT 算子落盘 排序算子 (SORT 算子) 的作用是将下层算子计算的结果进行排序。因为必须要拿到完整的数据后才能进行排序，所以该算子为阻塞性算子。 SORT 的算法 SORT 逻辑算子主要有三种，分别是普通排序，前缀排序和 top-n 排序。生成逻...