引导一个 Cursor 变量

Question

我试图在不移动光标的情况下获取下一条记录。即类似于 peek 函数的东西。这是我到目前为止编写的一些 sql 代码：

DECLARE
    @Id     varchar(80),
    @Name   varchar(80),
    @NextId varchar(80)

BEGIN

    SET @MyCursor = CURSOR FOR
    SELECT id,name FROM dbo.My_TABLE
    WHERE name like '%joe%';

    OPEN @MyCursor 
        FETCH NEXT FROM @MyCursor 
    INTO @Id, @Name

    WHILE @@FETCH_STATUS = 0
    BEGIN
        print 'Id is :: ' + cast(@Id as varchar(80)) + ' : ' + @Name
        SELECT @NextId=id, LEAD (id,1) OVER (ORDER BY id) FROM @MyCursor;
        print 'The next record is :: ' + @NextId
        FETCH NEXT FROM @MyCursor 
        INTO @Id, @Name
    END;

但是，我收到一条错误消息：

The variable '@MyCursor' is a cursor variable, but it is used in a place where a cursor variable is not valid.

当我发出 select 语句时，我可能会得到一些类似这样的数据

----+------
ID    NAME
----+------
5   + Joes
6   + FakeJoe
7   + Joes
8   + Joes
9   + MikeJoes

对我来说，比较 ID 5 和 6 以查看名称是否匹配很重要。如果是这样，比如 7 和 8，我想删除后面的记录。如果没有，比如5和6，我想留下记录

Answer 1

游标变量不属于 FROM。只需向查询本身添加一列：

SELECT id, name,
       LEAD(id) OVER (ORDER BY id) as next_id
FROM dbo.My_TABLE
WHERE name like '%joe%';

引导一个 Cursor 变量

LEAD over a Cursor variable

sql

sql-server

window-functions

database-cursor