2016年計算機三級數(shù)據(jù)庫SQL語句大全（3）

　　技巧
    1、1=1，1=2的使用，在SQL語句組合時用的較多
    “where 1=1” 是表示選擇全部 “where 1=2”全部不選，
    如：
    if @strWhere !=''
    begin
    set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere
    end
    else
    begin
    set @strSQL = 'select count(*) as Total from [' + @tblName + ']'
    end
    我們可以直接寫成
    set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere
     2、收縮數(shù)據(jù)庫
    --重建索引
    DBCC REINDEX
    DBCC INDEXDEFRAG
    --收縮數(shù)據(jù)和日志
    DBCC SHRINKDB
    DBCC SHRINKFILE
    3、壓縮數(shù)據(jù)庫
    dbcc shrinkdatabase(dbname)
    4、轉(zhuǎn)移數(shù)據(jù)庫給新用戶以已存在用戶權(quán)限
    exec sp_change_users_login 'update_one','newname','oldname'
    go
    5、檢查備份集
    RESTORE VERIFYONLY from disk='E:\dvbbs.bak'
    6、修復數(shù)據(jù)庫
    ALTER DATABASE [dvbbs] SET SINGLE_USER
    GO
    DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK
    GO
    ALTER DATABASE [dvbbs] SET MULTI_USER
    GO
    7、日志清除
    SET NOCOUNT ON
    DECLARE @LogicalFileName sysname,
    @MaxMinutes INT,
    @NewSize INT
    USE tablename -- 要操作的數(shù)據(jù)庫名
    SELECT @LogicalFileName = 'tablename_log', -- 日志文件名
    @MaxMinutes = 10, -- Limit on time allowed to wrap log.
    @NewSize = 1 -- 你想設定的日志文件的大小(M)
    Setup / initialize
    DECLARE @OriginalSize int
    SELECT @OriginalSize = size
    FROM sysfiles
    WHERE name = @LogicalFileName
    SELECT 'Original Size of ' + db_name() + ' LOG is ' +
    CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' +
    CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB'
    FROM sysfiles
    WHERE name = @LogicalFileName
    CREATE TABLE DummyTrans
    (DummyColumn char (8000) not null)
    DECLARE @Counter INT,
    @StartTime DATETIME,
    @TruncLog VARCHAR(255)
    SELECT @StartTime = GETDATE(),
    @TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY'
    DBCC SHRINKFILE (@LogicalFileName, @NewSize)
    EXEC (@TruncLog)
    -- Wrap the log if necessary.
    WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired
    AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName)
    AND (@OriginalSize * 8 /1024) > @NewSize
    BEGIN -- Outer loop.
    SELECT @Counter = 0
    WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000))
    BEGIN -- update
    INSERT DummyTrans VALUES ('Fill Log') DELETE DummyTrans
    SELECT @Counter = @Counter + 1
    END
    EXEC (@TruncLog)
    END
    SELECT 'Final Size of ' + db_name() + ' LOG is ' +
    CONVERT(VARCHAR(30),size) + ' 8K pages or ' +
    CONVERT(VARCHAR(30),(size*8/1024)) + 'MB'
    FROM sysfiles
    WHERE name = @LogicalFileName
    DROP TABLE DummyTrans
    SET NOCOUNT OFF　　
     8、說明：更改某個表
    exec sp_changeobjectowner 'tablename','dbo'
    9、存儲更改全部表
    CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch
    @OldOwner as NVARCHAR(128),
    @NewOwner as NVARCHAR(128)
    AS
    DECLARE @Name as NVARCHAR(128)
    DECLARE @Owner as NVARCHAR(128)
    DECLARE @OwnerName as NVARCHAR(128)
    DECLARE curObject CURSOR FOR
    select 'Name' = name,
    'Owner' = user_name(uid)
    from sysobjects
    where user_name(uid)=@OldOwner
    order by name
    OPEN curObject
    FETCH NEXT FROM curObject INTO @Name, @Owner
    WHILE(@@FETCH_STATUS=0)
    BEGIN
    if @Owner=@OldOwner
    begin
    set @OwnerName = @OldOwner + '.' + rtrim(@Name)
    exec sp_changeobjectowner @OwnerName, @NewOwner
    end
    -- select @name,@NewOwner,@OldOwner
    FETCH NEXT FROM curObject INTO @Name, @Owner
    END
    close curObject
    deallocate curObject
    GO
    10、SQL SERVER中直接循環(huán)寫入數(shù)據(jù)
    declare @i int
    set @i=1
    while @i<30
    begin
    insert into test (userid) values(@i)
    set @i=@i+1
    end
    案例：
    有如下表，要求就表中所有沒有及格的成績，在每次增長0.1的基礎上，使他們剛好及格:
    Name score
    Zhangshan 80
    Lishi 59
    Wangwu 50
    Songquan 69
    while((select min(score) from tb_table)<60)
    begin
    update tb_table set score =score*1.01
    where score<60
    if (select min(score) from tb_table)>60
    break
    else
    continue
    end