SELECT name, score, CASE WHEN score >= 90 THEN 'A' WHEN score >= 80 THEN 'B' WHEN score >= 70 THEN 'C' ELSE 'D' END AS grade_level FROM students; 执行结果如下: CASE表达式在SQL查询中用途广泛,可用于SELECT、UPDATE的SET等语句中,实现动态计算列值、根据条件更新值等功能。分组连接函数:G...
sql="select * from 数据表 where 字段名 in ('值1','值2','值3')" sql="select * from 数据表 where 字段名 between 值1 and 值2" (2) 更新数据记录: sql="update 数据表 set 字段名=字段值 where 条件表达式" sql="update 数据表 set 字段1=值1,字段2=值2 …… 字段n=值n where 条件...
从其他表更新表(Update from Another Table)是一种SQL操作,它允许你根据一个或多个表的值来更新另一个表的记录。这种操作通常用于数据同步、数据转换或数据清洗等场景。 相关优势 数据一致性:通过从一个表更新另一个表,可以确保两个表之间的数据保持一致。 简化操作:相比于手动更新每一条记录,使用SQL语句可以大大...
In some cases, we may need to update the whole table or all rows in a table for a specific column. In this case, we do not need a condition because we will match all table rows. In this example, we will set all users table records Age value to the 30. 在某些情况下,我们可能需要...
How to UPDATE from SELECT in SQL Server 本文介绍了Inner Join更新数据、MERGE同时更新和插入的使用。 文中短句: alter the contents of a table indirectly:间接地更新表的内容 direct references:直接引用 by using a subset of data:通过使用数据的子集 ...
You can use SELECT FROM statement to retrieve data from this table, then use an INSERT INTO to add that set of data into another table, and two statements will be nested in one single query.
UPDATE your_table SET column1 = subquery.column1, column2 = subquery.column2 FROM ( SELECT id, new_value1 AS column1, new_value2 AS column2 FROM your_table WHERE your_condition ) AS subquery WHERE your_table.id = subquery.id; 复制代码 使用JOIN语句:可以通过使用JOIN语句将要更新的数据与...
改的基本语法:UPDATE 表名 SET 列名 = 新的值; 删的基本语法:DELETE FROM 表名; 现在来模拟一下场景: 1、修改作者名: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 UPDATEbookshelfSETauthor='Margaret Mitchell';COMMIT; 修改作者名 2、下架图书: ...
DELETE FROM student WHERE s_id IN (SELECT s_id FROM other_table WHERE condition); 3.3 UPDATE UPDATE 是 SQL 中用于修改数据库表中现有记录的重要命令。 语法 UPDATE table_name SET column1 = value1, column2 = value2, ... WHERE condition; table_name:要更新的表的名称。 SET:指...
SQL Update From Select The problem with the simple UPDATE statement is that it can only take a single table. Why would we want to include a second table? We may have acolumn in one tablebut thevalues for that are derived or calculated from data in another table. ...