declare cursor [del_cursor] is select a.*, a.rowid row_id from [table_name] a order by a.rowid; begin for v_cusor in [del_cursor] loop if v_cusor.[time_stamp] < to_date('2014-01-01','yyyy-mm-dd') then delete from [table_name] where rowid = v_cusor.row_id; end if...
SpecifyWITH CHECK OPTIONto indicate that Oracle Database prohibits any changes to the table or view that would produce rows that are not included in the subquery. When used in the subquery of a DML statement, you can specify this clause in a subquery in the FROM clause but not in subquery...
MySQL在删除一张表时出现 ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails 原因 可能是在Mysql中,删除的表和另一张表设置了foreign key的关联,造成无法更新或删除数据; 解决方案 可以通过设置FOREIGN_KEY_CHECKS变量来避免这种情况。 禁用外键约束 代码语言:javascript ...
...CASCADE: A "CASCADE" action propagates the delete or update operation on the parent key to each dependent...For an "ON DELETE CASCADE" action, this means that each row in the child table that was associated with 2.1K30 C# 数据操作系列 - 12 NHibernate的增删改查...
假设我们要删除order_history上order_id<1999999的所有记录, 占到总行数的50%。由于order_history是非分区表,所以这里无法用Oracle的并行执行Parallel Execution来加速操作。 因此我们利用上述脚本来构造多条DML语句: SQL> @rowid_chunk Enter value for rowid_ranges: 24 ==>这里输入要构造的rowid分区个数 ...
而truncate操作在Oracle,MySQL都是一个极快的过程,在Oracle中不会直接抹去数据,数据还是依旧存在,在一定的条件下触发才会回收。 我们使用dbms_rowid来解析一下 SQL> select dbms_rowid.ROWID_RELATIVE_FNO(rowid) as file#,dbms_rowid.ROWID_BLOCK_NUMBER(rowid) as block#,dbms_rowid.ROWID_ROW_NUMBER(rowid) as...
In this post we'll start with a quick recap ofhow delete works. Then look at several alternatives you can use in Oracle Database to remove rows faster: Removing all the rows fast withtruncate Usingcreate-table-as-selectto wipe a large fraction of the data ...
By adding a column name to the PropertiesToExcludeOnCompare, will allow it to be inserted and updated but will not update the row if any of the other columns in that row did not change. For example, if you are importing bulk data and want to remove from comparison an internal Create...
Semi-consistent read is a performance feature, supported by InnoDB in isolation levels weaker than REPEATABLE READ; quoting from handler.h: " Normally, when running UPDATE or DELETE queries, we need to wait for other transactions to release their locks on a given row before we can read it ...
All rows in Oracle have a rowid. This is a physical locator. That is, it states where on disk Oracle stores the row. This unique to each row. So you can use this value to identify and remove copies. To do this, replace min() with min(rowid) in the uncorrelated delete: ...