Question

我的脚本出现问题，因为它会搜索包含＆＃39; Dummy＆＃39;在表名中。我有一个SELECT查询，其结果将是要删除的表。

    SELECT  Row_Number() Over (Order By name) As RowNum
                        , name
                FROM    sys.all_objects
                WHERE   type = 'U'
                        and name like '%Dummy%'
                        and schema_id = @schemaID

然后又回来了：

    RowNum  name

    1   Dummy

    2   DummyJoinTbl1

    3   DummyJoinTbl2

    4   DummyJoinTbl3

但是当我执行下面的脚本时，

    DECLARE

    @schemaName nvarchar(100),
    @schemaID int,
    @tblName nvarchar(100) = '',
    @cnt int = 1,
    @rowNumber int = 1,
    @SQL nvarchar(100)

    SET @schemaName = (select SCHEMA_NAME()) -- this is dbo
    SET @schemaID = (select SCHEMA_ID()) -- this is 1

    BEGIN

    WHILE (@cnt > 0)
        BEGIN
            SELECT @tblName = +name
            FROM 
                (
                SELECT  Row_Number() Over (Order By name) As RowNum
                        , name
                FROM    sys.all_objects
                WHERE   type = 'U'
                        and name like '%Dummy%'
                        and schema_id = @schemaID
                ) ReferenceTable    
            WHERE RowNum = @rownumber

            SET @cnt = @@ROWCOUNT
            SET @rownumber = @rownumber + 1

            IF (@cnt > 0)
            BEGIN
                PRINT 'DROP TABLE ' + @schemaName + '.' + @tblName + ' - RowCount:' + cast(@cnt as nvarchar(100))
                set @SQL = 'DROP TABLE ' + @schemaName + '.' + @tblName
                exec sp_executesql @SQL

            END

        END

        PRINT 'DONE'

    END

它返回的结果：

    DROP TABLE dbo.Dummy - RowCount:1
    DROP TABLE dbo.DummyJoinTbl2 - RowCount:1
    DONE

错过其他牌桌的原因可能是什么？当我删除

    set @SQL = 'DROP TABLE ' + @schemaName + '.' + @tblName
        exec sp_executesql @SQL

它将打印所有表格。

    DROP TABLE dbo.Dummy - RowCount:1
    DROP TABLE dbo.DummyJoinTbl1 - RowCount:1
    DROP TABLE dbo.DummyJoinTbl2 - RowCount:1
    DROP TABLE dbo.DummyJoinTbl3 - RowCount:1
    DONE

请注意，给定的表格都是空的。提前谢谢。

Answer 1

这是使用光标的理想场所，如果你这样做，你将需要更少的代码。这是一个简化的示例，它假设您只想从单个DB中删除表：

USE TempDB1;

CREATE TABLE test1 (i INT);
CREATE TABLE test2 (i INT);
CREATE TABLE test3 (i INT);
CREATE TABLE test4 (i INT);

DECLARE @tableName VARCHAR(200),
    @sql NVARCHAR(MAX);

DECLARE c CURSOR FAST_FORWARD FOR
SELECT  name
FROM    sys.all_objects
WHERE   type = 'U'
        AND name LIKE '%test%'
        AND schema_id = SCHEMA_ID();

OPEN c;
FETCH NEXT FROM c INTO @tableName;

WHILE @@FETCH_STATUS = 0
BEGIN
    SET @sql = 'DROP TABLE ' + @tableName;
    PRINT @sql;
    EXEC sp_executesql @sql;

    FETCH NEXT FROM c INTO @tableName;
END;

CLOSE c;
DEALLOCATE c;

Answer 2

那是因为删除第一个表后select语句的结果变为下一个：

1   DummyJoinTbl1

2   DummyJoinTbl2

3   DummyJoinTbl3

这是跳过DummyJoinTbl1的原因，因为@rownumber = 2.下一个循环@rownumber = 3并且它超过了记录数。不要使用WHERE RowNum = @rownumber

使用SELECT TOP（1）@tblName = + name而不嵌套select和ROW_NUMBER（）

使用1选择游标而不是在WHILE语句中选择N次也更好

在IF stament和WHILE循环中执行sp_executesql

2 个答案: