The WHERE clause of the outer query uses a > ANY condition to check for duplicates. It will delete any row that has a rowid greater than at least one other row. This ensures that all but one of the rows that match your conditions is met, therefore removing all duplicates. So, how doe...
Let’s check which rows got deleted. select * from customers2 go Scenario 2.b: Delete all duplicate records but keep the first original one Let’s first truncate the customers2 table and add the same rows again. Truncate Table customers2 go Insert into customers2 Values(1, 'John', 'Pari...
If we look at the result set, we can easily understand thatBookNumber: 3andBookNumber: 4are duplicate rows. Previously, it was explained in detailhow to remove duplicates in SQL. We must delete them to keep the database consistent. Again, the following options arise: Delete where book numb...
1.selectdistinct director from movies order by director asc; where语句可以不写,灵活使用 Since theDISTINCTkeyword will blindly remove duplicate rows, 拓展:SELECT id,title,director FROM Movieswhere director like "%John%"order by title asc 2.select title,year from movies order by year desc limit 4...
rows. LooseScan: Scan a subquery table using an index that enables a single value to be chosen from each subquery's value group. Materialize the subquery into an indexed temporary table that is used to perform a join, where the index is used to remove duplicates. The index might also be...
开始我们拿sql到数据库查询平台查库执行计划,无奈这个平台有bug,delete语句无法查看,所以我们改成select,“应该”是一样。这个“应该”加了双引号,导致我们走了一点弯路。 EXPLAINSELECT*fromt_table_1wheretask_idin(selectidfromt_table_2whereuid=1)
And Oracle puts rowids of the duplicates in the exceptions table! Note that this doesn't remove the failing rows. You still need to do that yourself. But it does find them for you. You can use this information to filter the rows you're deleting: ...
,可以通过以下步骤实现: 1. 首先,确保你已经连接到数据库,并执行了SQL查询语句,将结果保存在一个多维数组中。 2. 确定要删除的行的索引或标识符。可以根据特定的条件来确定要删除的行,比如某个...
)WITH(...);--remove duplicate rows on order_id and keep the first occurrence row,--because there shouldn't be two orders with the same order_id.SELECTorder_id,user, product, numFROM(SELECT*, ROW_NUMBER()OVER(PARTITIONBYorder_idORDERBYproctimeASC)ASrow_numFROMOrders)WHERErow_num=1 ...
--Create a temporary database to store the necessary rows required to remove the duplicate data USE master GO IF EXISTS(SELECT 1 FROM sys.databases WHERE name = 'dbChangeTrackingMetadata') BEGIN DROP DATABASE dbChangeTrackingMetadata END GO CREATE DATABASE dbChangeTrackingMetadata GO --Table to...