在Oracle SQL中使用WITH DELETE FROM语句可以实现删除操作。WITH DELETE FROM语句结合了WITH子句和DELETE FROM语句,可以在删除数据的同时使用WITH子句定义临时表达式,提供更灵活和高效的删除操作。 具体语法如下: 代码语言:txt 复制 WITH <临时表达式> DELETE FROM <表名> [WHERE <条件>]; 其中,临时表达式可以是一...
The SQL-99 “WITH clause” is very confusing at first because the SQL statement does not begin with the word SELECT. Instead, we use the “WITH clause” to start our SQL query, defining the aggregations, which can then be named in the main query as if they were “real” tables: WITH...
1.UPDATE语句 updateemployeessetsalary=(selectavg(high_salary)fromsalary_grades)whereemployee_id=4); 2.DELETE语句 deletefromemployeeswheresalary>(selectavg(high_salary)fromsalary_grades); 七、WITH语句 withcustomer_purchasesas(selectcu.customer_id,sum(pr.price*pu.quantity)aspurchase_totalfromcustomers c...
1.with子句只能被select查询块引用,一般在with查询用到多次情况下。在引用的select语句之前定义,同级只能定义with关键字只能使用一次,多个用逗号分割。 2.with子句的返回结果存到用户的临时表空间中,只做一次查询,反复使用,提高效率。 3.在同级select前有多个查询定义的时候,第1个用with,后面的不用with,并且用逗号隔...
SQL DELETE 语句 DELETE 语句用于删除表中的行。 语法 DELETE FROM 表名称 WHERE 列名称 = 值 ...
利用WITH定义查询中出现多次的子查询还能带来性能提示。Oracle会对WITH进行性能优化,当需要多次访问WITH定义的子查询时,Oracle会将子查询的结果放到一个临时表中,避免同样的子查询多次执行,从而有效的减少了查询的IO数量。 可惜的是,WITH语句只能用在SELECT语句中,UPDATE和DELETE语句不支持WITH语法: ...
如下的with as语句,不能放在insert前,而是放在紧接着要调用的地方前 insert into T_finance_ExpenseRemburseItem2 (FID, FKREMBURSEMENTID, FAMOUNT, FKCREATEBYID, FCREATETIME, FKCUID, FKCOSTTYPEID, FCOSTTYPENAME) with verificationInfo as (select ment.fnumber, ...
create [or replace] trigger 触发器名 {before | after} {delete | insert | update [列名]| on 表名 [for each row [when(条件)]] PLSQL块 示例:在emp表创建触发器,插入数据时打印“成功插入新员工” create trigger firsttrigger after insert on emp declare begin dbms_output.put_line('成功插入...
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SQL> SQL> SQL> SQL> SQL> SQL> SQL> delete mand with conditions SQL> SQL> delete from Employee where Salary > ;rows deleted SQL> SQL> select * from Employee;ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION Jason Martin JUL JUL Toronto...