7、在外层中,truncate或者delete后,其占用的空间都将释放。 8、truncate和delete只删除数据,而drop则删除整个表(结构和数据)。 delete 用法 Oracle Delete Statements Version 10.2 Basic Delete Statements 1.Delete All Rows: DELETE <table_name> or
Delete All Records It is possible to delete all rows in a table without deleting the table. This means that the table structure, attributes, and indexes will be intact: DELETE FROMtable_name; or: DELETE * FROMtable_name; Delete All Null Records delete * from emp where comm is null; dele...
If no condition is specified, all of the rows in the table are deleted. Examples Delete all of the rows from the CATEGORY table: delete from category; Delete rows with CATID values between 0 and 9 from the CATEGORY table: delete from category where catid between 0 and 9; Delete rows ...
Delete: Delete all rows of a table using a delete query Clear: Delete all rows of a table using RemoveRange method using System.Data.Entity; using System.Linq; namespace EfHelper.Database.Core { public static class EfCleanHelper { public static void Clear<T>(this DbContext context) where...
oracle在删除表时没有直接将表所占的块清空,只是对该表的数据块做了可以被覆写的标志。oracle将已删除的表的信息放到了一个虚拟容器“回收站”中,所以在块未被重新使用前还可以恢复。 具体步骤: 查询这个“回收站”或者查询user_table视图来查找已被删除的表: ...
select TABLE_NAME,NUM_ROWS from dba_tables where OWNER='xxx' order by NUM_ROWS desc; 1. 整理好后交给开发,确认各大表是否可清理,需保存多久数据。 二、 清理分类 目前大致遇到以下几种场景: 1. 可以drop 备份表、临时表、已无用的表 时间范围分区表:索引改为local索引后,按分区drop ...
1.Alter table : 1.添加和修改列 2.添加和删除约束 3.enable,disable约束 2.drop table命令移除表中所有行和表结构 3.rename,truncate,comment 4.当执行以上DDL语句时,事务自动提交 三、详细说明 1.增加列: 语法: 代码语言:javascript 代码运行次数:0 ...
ndb_delete_all deletes all rows from the given NDB table. In some cases, this can be much faster than DELETE or even TRUNCATE TABLE. Usagendb_delete_all -c connection_string tbl_name -d db_name This deletes all rows from the table named tbl_name in the database named db_name. It...
int delete_rows=10000; ... 1. CHAR类型数组变量 EXEC SQL for :delete_rows delete FROM table_name WHERE a= :a; 由于char对应于Oracle的char类型,因此若有空格,则此时char即使用memset初始化,但也会带有后面的空格,有可能造成delete时where a=:a由于空格不匹配无法删除,例如:a赋值为'a’,但数组长度是...
在Oracle数据库中,TRUNCATE TABLE 和 DELETE 语句都可以用于删除数据,但它们的实现方式和效率是不同的。 TRUNCATE TABLE 是一种数据截断操作,它会删除表中的所有数据,并且将表的存储空间释放回表空间。TRUNCATE TABLE 是一个DDL(数据定义语言)操作,执行过程中会获取表级锁,将表进行重建,并且在事务日志中记录相应的...