为什么此查询与错误的数据库名称匹配？

Question

为什么'TestDatabase2'也匹配'TestDatabase'？类似地,'D2'也匹配'D'.

exec sp_executesql N'SELECT TOP 1
                    sdb.name AS DbName,
                    bus.backup_start_date AS LastBackUpTime,
                    bus.type AS Type
                FROM
                    sys.sysdatabases sdb 
                LEFT OUTER JOIN
                    msdb.dbo.backupset bus
                ON
                    bus.database_name = sdb.NAME
                    AND
                    bus.type = @backupType
                WHERE
                    sdb.name = @dbname
                ORDER BY
                    LastBackUpTime DESC',N'@dbName nvarchar(12),@backupType nvarchar(1)',@dbName=N'TestDatabase',@backupType=N'D'

Answer 1

数据库名称的参数是NVARCHAR(12).

猜猜有多少个字符TestDatabase;)

SELECT CAST('TestDatabase' as NVARCHAR(12)), CAST('TestDatabase12314' as NVARCHAR(12))

你应该把它变成a NVARCHAR(128)或a SYSNAME,这是msdb.dbo.backupset.database_name和sys.databases.name列的长度.