因此,delete语句用于使用where子句从表中删除行,以仅选择要删除的行。 始终使用唯一标识符来查找需要删除的行。 要删除表中的所有行,请始终使用TRUNCATE TABLE。TRUNCATE TABLE比SQL删除语句更快,并且它使用更少的系统和事务日志资源。 默认情况下,DELETE语句会在表上引发独占(X)锁定,并在事务完成之前保持锁定。 独占...
DELETE, DELETE - SQL uses record locking when marking multiple records for deletion in tables opened for shared access. This reduces record contention in multiuser situations, but may reduce performance. For maximum performance, open the table for exclusive use or use FLOCK( ) to lock the table...
exec sp_msforeachtable "truncate table ?" --删除当前数据库所有表中的数据 sp_MSforeachtable @command1='Delete from ?' sp_MSforeachtable @command1 = "TRUNCATE TABLE ?" 1. 2. 3. 4. 该方法可以一次清空所有表,但不能加过滤条件. --- ---...
Use the TRUNCATE TABLE command (deletes only the data inside the table): 当我们只想将表内的数据做完成清楚而保留其内部结构的话,可以使用TRUNCATE TABLE命令(仅仅删除表中的数据) TRUNCATE TABLE table_name
for the specified shell config Modify sqlconfig files using subcommands like "sqlcmd config use-context mssql" create Install/Create SQL Server, Azure SQL, and Tools delete Uninstall/Delete the current context help Help about any command open Open tools (e.g ADS) for current context query ...
SCOTT@PROD>create table testasselect*from emp;SCOTT@PROD>insert into test select*from test;SCOTT@PROD>/ 代码语言:javascript 代码运行次数:0 运行 AI代码解释 SCOTT@PROD>deletefrom test;SCOTT@PROD>commit; 代码语言:javascript 代码运行次数:0
for the specified shell config Modify sqlconfig files using subcommands like "sqlcmd config use-context mssql" create Install/Create SQL Server, Azure SQL, and Tools delete Uninstall/Delete the current context help Help about any command open Open tools (e.g ADS) for current context query ...
删的基本语法:DELETE FROM 表名; 现在来模拟一下场景: 1、修改作者名: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 UPDATEbookshelfSETauthor='Margaret Mitchell';COMMIT; 修改作者名 2、下架图书: 代码语言:javascript 代码运行次数:0 运行
Visual FoxPro uses the default value if you use the SQL ALTER TABLEcommand to remove autoincrementing for the field.PRIMARY KEY | UNIQUE PRIMARY KEY creates a primary index for the field specified in FieldName1. UNIQUE creates a candidate index for the field specified in FieldName1. The ...
After reading and re-re-re-reading the mysql documentation about the DELETE command, I still don't understand why my queries don't work.. I would like to use the multi-table deletion to save a few queries. I have tree tables A(ID_A) ...