title SELECT NULL in SQL Server section Understanding SELECT NULL: "Using SELECT NULL to insert empty values" section Using SELECT NULL for condition filtering: "Filtering rows without specific values" section Combining SELECT NULL with other fields: "Creating new result sets with empty values and ...
insert(a.msid,a.bill_month,a.areacode) values(b.msid,'200702',b.areacode); update acct set areacode=800 where msid=905320001; delete from acct where areacode=533 or areacode=531; insert into acct values(905320001,'200702',800,0.00); --删除重复行 delete from subs b where b.rowid<...
(pid,pname,price,category_id) VALUES(11,'好想你枣',56,'c004'); INSERT INTO product(pid,pname,price,category_id) VALUES(12,'香飘飘奶茶',1,'c005'); INSERT INTO product(pid,pname,price,category_id) VALUES(13,'果9',1,NULL); INSERT INTO product(pid,pname,category_id) VALUES(14,'...
Debug.Print 'Loopthroughthe Recordset; print the record ' number and field values. rst.MoveFirstForlngRecCount =0TolngRecords -1Debug.PrintRight(Space(6) & _Str(lngRecCount),6) &" "; For lngFldCount = 0 To lngFields - 1 'CheckforNullvalues.IfIsNull(rst.Fields(lngFldCount))Then...
我们希望仅在SELECT查询返回非NULL值时更新salary字段。 代码语言:txt 复制 -- 创建示例表 CREATE TABLE employees ( id INT PRIMARY KEY, name VARCHAR(100), salary DECIMAL(10, 2) ); -- 插入示例数据 INSERT INTO employees (id, name, salary) VALUES (1, 'Alice', 50000); INSERT INTO employees (...
并且,两个null值并不相等,不产生unknown值的话是不能做比较的。 准备数据: ##创建表 CREATE TABLE EducationType ( EducationTypeIDintnotnull, EducationTypeName VARCHAR(40) notnull, EducationTypeRemark VARCHAR(40)null) ##插入数据 insert INTO EducationType (EducationTypeID,EducationTypeName) values (1,'zh...
以下是使用 INNER JOIN 的示例查询,它将连接两个查询结果,并排除包含 NULL 值的行: SELECTDISTINCTt1.Name, t1.AgeFROMTableName t1INNERJOIN(SELECT*FROMTableNameWHERENameISNOTNULL) t2ONt1.ID=t2.ID; SQL Copy 结果如下: +---+---+|Name|Age|+---+---+|John|25||Mike|30|+---+---+ SQL...
select * from sc where grad is null grad是null,select * from sc where grad = "" grad是""空字符串 你要理解NULL与""的区别.Null 是没有的意思 不占用内存空间 ""是空的字符串 它是一个字符串，不过里面没有内容 我
我想使用一个SQL select语句,该语句的条件是“如果列a为NULL,则将列B的值更改为等于列C的值”。如何将此逻辑合并到SELECT语句中(不是UPDATE语句,因为我无法更改服务器上的表,但希望从服务器上查询它们)。 SELECT final.* FROM final 实际的表如下图所示,在这里,如果更改列为null,我想更改Old列以匹配Direct...
使用Transact-SQL的INSERT INTO语句向BookInfo表中添加数据的代码如下:USE Library INSERT INTO BookInfo (bookid,bookname,publish,pubdate,price,author,store,reader) VALUES(4001,' HTML教程','青年出版社','2004-9-1', 35.00,'王宾,李宏',1,9702) INSERT INTO BookInfo (bookid,bookname,publish,pubdate,...