最近在使用abap delete duplicate时发现删除重复记录不完全。 只删除掉了部分重复记录。最后经过调试,没发现其它问题。于是再次研究delete duplicate语法 发现delete duplicate只删除相邻行的重复项,保留第一条记录,所以在对内表进行delete duplicate 操作时应该注意先对内表进行排序,然后再执行delete duplicate语句,即可将重...
(1) drop table:直接表都删没;当不需要该表时,可以使用该方法。 (2) truncate table:删除所有数据,同时保留表,速度很快。 画外音:可以理解为,drop table然后再create table。 (3) delete from table:可以删除所有数据,也能保留表,但性能较差。也可以带where条件删除部分数据,灵活性强。 虽然truncate和delete都...
andTable.tel=#TMP.tel and(Table.address=#TMP.addressorTable.addressisnull) Select*from#TMP DeleteFromTableWhereidin(SelectidFrom#TMP) DropTable#TMP 简单吧..如果你想说只删掉前面的或只删除后面的,那么加入排序. 值得注意的是字段如果是NULL的话,要像我一样加入 "or Table.address is null".不然不会...
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Delete from table_name where (set conditions here) limit 1 The "limit 1" will prevent the query from going beyond this threshold of results to delete. You may want to backup the table in question before you go forward with this. http://forums.mysql.com/read.php?21,135990,...
This way, you can find the duplicate rows using the COUNT() function. How to Delete Duplicates in Postgres Using a DELETE USING Statement? To delete duplicate rows from a table, use the below statement: DELETE FROM programming_languages dup_lang ...
delete from t_table_1 where task_id in (select id from t_table_2 where uid = #{uid}) 1. 拿到报错的参数,查询要删除的数据也不多,联系dba同学确认没有死锁日志,但出现大量慢sql,那为什么这条sql会是慢sql呢? 问题复现 表结构简化如下:
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。
I want a code in Visual foxpro 9.0 that can delete duplicate records. The detailed I have a table name Mymaster. I want to delete records that have the same Taxapayer and the same Tax_office as shown below; for example; 2ND OCTOBER COMPANY LIMITED has the same tax_office. ...
basically I want to remove the xxxx@nowhere.com row where the cust_type is equal to 1...but only when there's a duplicate entry. Can anyone explain the syntax that I would have to use? I've tried looking into COUNT() and stuff like that but the combined syntax of COUNT() and DE...