在 SQL GROUP BY 子句中,如果在 Group by 子句中也使用了列,我们可以在 select 语句中使用该列。它不允许 select 子句中的任何列不是 GROUP BY 子句的一部分(抛开聚合函数,比如 count、sum、min 等等)。 ERROR: column "course.language_id" must appear in the GROUP BY clause or be used in an aggreg...
1mysql>CREATETABLEusers2(3"id"int(10) unsignedNOTNULL,4"name"varchar(100)DEFAULTNULL,5"birth"datetime6) ENGINE=InnoDBDEFAULTCHARSET=utf8;7Query OK,0rows affected 3.1.2 分表语句 1mysql>createtableusers_part2(3"id"int(10) unsignedNOTNULL,4"name"varchar(100)DEFAULTNULL,5"birth"datetime6) ...
postgres=# set constraint_exclusion = on; SET postgres=# explain select count(*) from measurement where logdate >= '2017-11-22'; QUERY PLAN --- Aggregate (cost=56.38..56.39 rows=1 width=0) -> Append (cost=0.00..53.29 rows=1235 width=0) -> Seq Scan on measurement (cost=0.00..0.0...
2017-04-01) 通过以下SQL命令来对表example_db.example_range_tbl2 增加一个分区: 代码语言:javascript 代码运行次数0 运行 AI代码解释 mysql> ALTER TABLE example_db.examplerange_tbl2 ADD PARTITION p201705 VALUES LESS ("2017-06-01"); Query OK, 0 rows affected (0.05 sec) 注意:关于操作分区...
2.发送你想要分析的sql语句,例如: select * from employees where first_name <'Bader' order by last_name; 1. 3.分析查询结果 select * from `information_schema`.optimizer_trace where query like '%Bader%'; 1. 得到如下结果: 分析trace结果: ...
-> PARTITION BY HASH( TO_DAYS(added) ) -> PARTITIONS 4; #ERROR 1503 (HY000): A PRIMARY KEY must include all columns in the table's partitioning function mysql> ALTER TABLE np_pk -> PARTITION BY HASH(id) -> PARTITIONS 4; Query OK, 0 rows affected (0.11 sec) ...
in set (0.00 sec) mysql> DELETE FROM employees PARTITION (p0, p1) -> WHERE fname LIKE 'j%'; Query OK, 2 rows affected (0.09 sec) mysql> SELECT * FROM employees WHERE fname LIKE 'j%'; +---+---+---+---+---+ | id | fname | lname | store_id | department_id | +-...
(SQL on OBS or Hadoop) CREATE FOREIGN TABLE (for OBS Import and Export) CREATE FOREIGN TABLE (SQL on other GaussDB(DWS)) CREATE FUNCTION CREATE GROUP CREATE INDEX CREATE REDACTION POLICY CREATE ROW LEVEL SECURITY POLICY CREATE PROCEDURE CREATE RESOURCE POOL CREATE ROLE CREATE SCHEMA CREATE ...
This approach avoids the problem of a large response by not returning duplicate data. TransactionId –UTF-8 string, not less than 1 or more than 255 bytes long, matching the Custom string pattern #44. The transaction ID at which to read the partition contents. QueryAsOfTime –Timestamp. ...
In the query output of SQL PARTITION BY, we also get 15 rows along with Min, Max and average values. In the previous example, we get an error message if we try to add a column that is not a part of the GROUP BY clause. We can add required columns in a select statement with ...