With Duplicates as (select distinct a.custid as Customer_ID from customers2 a join customers2 b on a.custid <> b.custid and a.CustName = b.CustName and a.CustCity = b.CustCity and a.Passport_Number = b.Passport_Number ) Delete from Customers2 where custid in (select Customer_ID fr...
AI代码解释 CREATETABLESPACEtablespace_nameADDDATAFILE'file_name'#数据文件名USELOGFILEGROUPlogfile_group #自定义日志文件组,一般每组2个logfile。[EXTENT_SIZE[=]extent_size]#区大小[INITIAL_SIZE[=]initial_size]#初始化大小[AUTOEXTEND_SIZE[=]autoextend_size]#自动扩宽尺寸[MAX_SIZE[=]max_size]#单个文件最...
#插入100W数据 mysql> call insert_user_data(1000000); Query OK, 0 rows affected (35.99 sec) #添加相关索引 mysql> alter table user add index idx_name(name), add index idx_phone(phone); Query OK, 0 rows affected (6.00 sec) Records: 0 Duplicates: 0 Warnings: 0 #表上索引统计信息 mysql...
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 used l...
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)
Select the "Users" folder, then double-click to open the user folder you are currently using.Step 5: Click the View tab in the top ribbon and select the Preview Pane. Then in the Layout section, select Details.Step 6: Move to Current view section, click on Group by and select Name,...
SQL -- Specify the remote data source using a four-part name-- in the form linked_server.catalog.schema.object.DELETEMyLinkServer.AdventureWorks2022.HumanResources.DepartmentWHEREDepartmentID >16; GO G. 通过使用 OPENQUERY 函数从远程表删除数据 ...
1SELECT句法23SELECT[STRAIGHT_JOIN]4[SQL_SMALL_RESULT][SQL_BIG_RESULT][SQL_BUFFER_RESULT]5[SQL_CACHE | SQL_NO_CACHE][SQL_CALC_FOUND_ROWS][HIGH_PRIORITY]6[DISTINCT | DISTINCTROW | ALL]7select_expression,...8[INTO {OUTFILE | DUMPFILE} 'file_name' export_options]9[FROM table_references10...
"How do I find duplicate rows using SQL?" This is often closely followed with: "How do I delete all but one of the copies?" In this post we'll look at how you can use SQL to: Find duplicate rows Delete duplicate rows Stop people storing new duplicates!
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