--下方的分号;用来分隔行 select distinct user_id from Test;--返回1;2select distinct user_id,user_type from Test;--返回1,1;1,2;2,1select user_id from Test group by user_id;--返回1;2select user_id,user_type from Test grou
SQL> SET AUTOT TRACE SQL> SELECT T1.OBJECT_NAME, T1.OBJECT_TYPE,T2.TABLESPACE_NAME 2 FROM T1, T2 WHERE T1.OBJECT_NAME = T2.SEGMENT_NAMEAND T1.OBJECT_NAME IN 3 (SELECT INDEX_NAME FROM T3 WHERE T3.TABLESPACE_NAME= T2.TABLESPACE_NAME); 311 rows selected. Execution Plan --- 0 SELE...
name) values(8, "Tom"),(8, "David"), (10, "Andy"); Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from t_index; +---+---+---+ | id | age | name | +---+-
EXPLAIN ANALYZESELECTe.emp_id, e.emp_nameFROMemployee eJOIN(SELECTdept_id,AVG(salary)ASdept_averageFROMemployeeGROUPBYdept_id) tONe.dept_id=t.dept_idWHEREe.salary>t.dept_average;->Nested loopinnerjoin(actual time=0.722..2.354rows=6loops=1)->Tablescanone (cost=2.75rows=25) (actual time=0...
SQL>select count(last_name), first_name, phone_number 2from employee_tbl 3group by count(last_name), first_name, phone_number 4/ 输出: group by count(last_name), first_name, phone_number * ERROR at line 3: ORA-00934: group function is not allowed here ...
SELECTDISTINCTTOP150Class,NameFROMTestOPTION(MAXDOP1)结果其实只需要读取前202行，耗时也回到了正常的<...
-- select rows if the first name and country of a customer is uniqueSELECTDISTINCTcountry, first_nameFROMCustomers; Run Code Here, the command selects rows if combinations ofcountryandfirst_nameare unique. Meaning, the result will include each pair ofcountryandfirst_nameonly once. ...
SELECT q.query_id, qt.query_sql_text FROM sys.query_store_query_text qt INNER JOIN sys.query_store_query q ON qt.query_text_id = q.query_text_id WHERE query_sql_text like N'%ORDER BY ListingPrice DESC%' AND query_sql_text not like N'%query_store%'; GO 以下示例应用提示以强制...
select @max = @max -1 set rowcount @max delete from 表名 where 主字段 = @id fetch cur_rows into @id,@max end close cur_rows set rowcount 0 方法二 "重复记录"有两个意义上的重复记录,一是完全重复的记录,也即所有字段均重复的记录,二是部分关键字段重复的记录,比如Name字段重复,而其他字段不...
行间隔(ROWS interval)是基于计数的间隔。它准确定义聚合中包含的行数。以下 ROWS 间隔定义聚合中包括当前行和当前行之前的 10 行(因此总共 11 行)。 ROWS BETWEEN 10 PRECEDING AND CURRENT ROW WINDOW 1. 2. WINDOW 子句可用于在 SELECT 子句之外定义 OVER 窗口。它可以使查询更具可读性,还允许我们为多个聚合...