DROPTABLEIFEXISTSsales_table;CREATETEMPORARYTABLEsales_table(keyvarchar(6),customerIDvarchar(10),productIDvarchar(10),price float);INSERTINTOsales_tableVALUES('1','Customer1','Product1',100),('2','Customer1','Product1',200),('3','Customer1','Product2',100),('4','Customer2','Product2...
| tmp1 | CREATE TEMPORARY TABLE `tmp1` ( `id` int(11) NOT NULL) ENGINE=MyISAM DEFAULT CHARSET=utf8 | +——-+———-+ 1 row in set (0.00 sec) 内存表 mysql> create table tmp2(id int not null) TYPE=HEAP; Query OK, 0 rows affected (0.00 sec) mysql> show create table tmp2...
create tablecourse(cidint(3),cnamevarchar(20),tidint(3));create tableteacher(tidint(3),tnamevarchar(20),tcidint(3));create tableteacherCard(tcidint(3),tcdescvarchar(200));# 插入数据 insert into coursevalues(1,'java',1);insert into coursevalues(2,'html',1);insert into coursevalues(3...
For examples showing how to add or remove system versioning on an existing table, see System Versioning in Examples. For use cases, see Temporal Tables. This example creates a new temporal table linked to a new history table. SQL Copy CREATE TABLE Department ( DepartmentNumber CHAR (10) ...
EXPLAINSELECT*fromt_table_1wheretask_idin(selectidfromt_table_2whereuid=1) explain后可以看到是走了索引的 到这里可以总结: 1.没有死锁,这点比较肯定,因为没有日志,也符合我们的理解。 2.有慢sql,这点比较奇怪,通过explain select语句是走索引的,但数据库慢日志记录到,全表扫描,不会错。
Assume that you remove temporary objects such as temporary tables, table variables, or table-valued parameters in SQL Server. In this case, very large PAGELATCH_EX contentions may occur on thesys.sysobjvaluessystem base table. Resolution
• json_remove(字段,'$.键')：删除某个json数据。• ...：还有一些其他json类型的函数，这里不再说明，一般json类型用的较少。• enum(选项1,选项2...选项n)：新增数据时只能从已有的选项中选择一个并插入。• set(选项1,选项2...选项n)：新增数据时可以从已有的选项中选择多个并插入。• eome...
CREATE TABLE dbo.doc_exb ( column_a INT, column_b VARCHAR(20) NULL, column_c DATETIME, column_d INT) ; GO -- Remove a single column. ALTER TABLE dbo.doc_exb DROP COLUMN column_b ; GO -- Remove multiple columns. ALTER TABLE dbo.doc_exb DROP COLUMN column_c, column_d; B. 制...
Specify TRUNCATE PARTITION to remove all rows from partition or, if the table is composite partitioned, all rows from partition's subpartitions. Specify TRUNCATE SUBPARTITION to remove all rows from subpartition. If table is index organized, Oracle also truncates any corresponding mapping table ...
Duplicate Weedout: Run the semijoin as if it was a join and remove duplicate records using a temporary table. FirstMatch: When scanning the inner tables for row combinations and there are multiple instances of a given value group, choose one rather than returning them all. This "shortcuts" s...