WHERE 条件; 复制代码 使用表达式更新列的值: UPDATE 表名SET 列名= 表达式 WHERE 条件; 复制代码 使用子查询更新列的值: UPDATE 表名SET 列名= (SELECT 子查询) WHERE 条件; 复制代码 更新多个表的数据: UPDATE 表1 SET 列名= (SELECT 子查询) FROM 表1 JOIN 表2 ON 条件WHERE 条件; 复制代码 注...
2 set town=(select town from wwm5 where =wwm2.id) 3 where id=(select from wwm5 where =wwm2.id) 4 / 8 rows updated. 方法二: 与方法一道理相同,这里需要掌握EXIST的相关用法. SQL> update wwm2 set town=(select town from wwm5 where =wwm2.id) where exists (select 1 from wwm5 where...
(MS SQL Server)语句:update b set ClientName = a.name from a,b where a.id = b.id (Oralce)语句:update b set (ClientName) = (SELECT name FROM a WHERE b.id = a.id) (Mysql)语句:: UPDATE A, B SET A1 = B1, A2 = B2, A3 = B3 WHERE A.ID = B.ID update set from 语句格式...
SET name='数学', type='理学'WHERE id=1; 2、GreenPlum update与select结合 语法: UPDATE [only] table [[as] alias] SET {column= {expression |default} |(column [, ...])= ({expression |default}[, ...])}[, ...] [FROM fromlist] [WHERE condition| WHERE current of cursor_name]; ...
(Oralce)语句：update b set (ClientName) = (SELECT name FROM a WHERE b.id = a.id)(Mysql)语句：: UPDATE A, B SET A1 = B1, A2 = B2, A3 = B3 WHERE A.ID = B.ID update set from 语句格式 当where和set都需要关联⼀个表进⾏查询时，整个 update执⾏时，就需要对被...
begin;select * from user where id in (1,2) for update;update user set age=22 where id in (1,2);where条件中的id是数据库的主键范围，并且使用for update关键字，加了多个行锁，这个事务没有commit。此时，开启了另外一个事务2，也更新id=1的用户的年龄：begin;update user set age=23 where id=...
UPDATEeSETe.DepartmentName=d.DepartmentNameFROMEmployees eJOINDepartments dONe.DepartmentID=d.DepartmentIDWHEREe.EmployeeID=@EmployeeID; 1. 2. 3. 4. 5. 代码解析: UPDATE e: 选择要更新的表的别名为e(Employees表)。 SET e.DepartmentName = d.DepartmentName: 指定要更新的字段,将Employees表中的Depart...
子查询就是嵌套的 select 语句,可以理解为子查询是一张表 语法: where子句中使用子查询 案例: 找出高于平均薪资的员工信息。 from 语句中使用子查询 在from 语句中使用子查询,可以将该子查询看做一张 表 案例: 找出每个部门平均薪水的等级。 select 语句中使用子查询 ...
(Oralce)语句:updatebset(ClientName) = (SELECT nameFROMa WHERE b.id = a.id) (Mysql)语句::UPDATEA, BSETA1 = B1, A2 = B2, A3 = B3 WHERE A.ID = B.ID updatesetfrom语句格式 当where和set都需要关联一个表进行查询时,整个update执行时,就需要对被关联的表进行两次扫描,显然效率比较低。对于这...
SET Column1 = (SELECT ColumnFromTable2 FROM Table2 WHERE Table1.PrimaryKeyColumn = Table2.PrimaryKeyColumn)WHERE EXISTS (SELECT 1 FROM Table2 WHERE Table1.PrimaryKeyColumn = Table2.PrimaryKeyColumn);在这个例子中，子查询 (SELECT ColumnFromTable2 FROM Table2 WHERE Table1.PrimaryKeyColumn = ...