Question

使用TSQL检查SQL Server上是否存在数据库的理想方法是什么？似乎有多种方法可以实现这一点。

Answer 1

实际上最好使用：

IF DB_ID('dms') IS NOT NULL
   --code mine :)
   print 'db exists'

请参阅https://docs.microsoft.com/en-us/sql/t-sql/functions/db-id-transact-sql

Answer 2

来自微软的脚本：

DECLARE @dbname nvarchar(128)
SET @dbname = N'Senna'

IF (EXISTS (SELECT name 
FROM master.dbo.sysdatabases 
WHERE ('[' + name + ']' = @dbname 
OR name = @dbname)))

-- code mine :)
PRINT 'db exists'

Answer 3

IF EXISTS (SELECT name FROM master.sys.databases WHERE name = N'YourDatabaseName')
  Do your thing...

顺便说一句，这直接来自SQL Server Studio，因此如果您可以访问此工具，我建议您开始使用可用的各种“Script xxxx AS”功能。会让你的生活更轻松！：）

Answer 4

我喜欢@ Eduardo的答案，我喜欢接受的答案。我喜欢从这样的东西中取回一个布尔值，所以我为你们写了一遍。

CREATE FUNCTION dbo.DatabaseExists(@dbname nvarchar(128))
RETURNS bit
AS
BEGIN
    declare @result bit = 0 
    SELECT @result = CAST(
        CASE WHEN db_id(@dbname) is not null THEN 1 
        ELSE 0 
        END 
    AS BIT)
    return @result
END
GO

现在您可以像这样使用它：

select [dbo].[DatabaseExists]('master') --returns 1
select [dbo].[DatabaseExists]('slave') --returns 0

Answer 5

尝试

IF EXISTS 
   (
     SELECT name FROM master.dbo.sysdatabases 
    WHERE name = N'New_Database'
    )
BEGIN
    SELECT 'Database Name already Exist' AS Message
END
ELSE
BEGIN
    CREATE DATABASE [New_Database]
    SELECT 'New Database is Created'
END

Answer 6

另一种方法是将SqlDataReader与SqlConnection和SqlCommand一起使用。使用HasRows属性。如果数据库存在，则为true，如果数据库不存在，则为false。

示例（在此示例中，数据库名称为“匹配”）：

    string CreateDatabaseConnectionString="/*the connection string*/";

    public static bool DatabaseExists()
    {
        bool Count;
        string DatabaseCheckString = "select name from master.sys.databases where name='Matches'";
        SqlConnection MyConn = new SqlConnection(CreateDatabaseConnectionString);
        SqlCommand DatabaseExistsCommand = new SqlCommand(DatabaseCheckString, MyConn);
        MyConn.Open();
        SqlDataReader Reader = DatabaseExistsCommand.ExecuteReader();
        Count = Reader.HasRows;
        MyConn.Close();
        return Count;
    }

Answer 7

  Public Function SQLDatabaseExist(ByVal DefaultConnectionString As String, ByVal DataBaseName As String) As Boolean
Try
    'CREATE DATABASE
    Dim SqlString As String = ""
    SqlString = "SELECT CASE WHEN EXISTS (SELECT name FROM master.dbo.sysdatabases WHERE name = N'" & DataBaseName & "') THEN CAST (1 AS BIT) ELSE CAST (0 AS BIT) END"
    Dim ExcRet As Integer = 0
    Using connection As New SqlConnection(DefaultConnectionString)
        Dim command As New SqlCommand(SqlString, connection)
        command.Connection.Open()
        ExcRet = command.ExecuteScalar()
        command.Connection.Close()
        command.Dispose()
    End Using
    Return ExcRet
Catch ex As Exception
    Return False
End Try

结束函数

''注意连接字符串中的初始目录必须是master！ '示例默认连接字符串

Dim DefaultConnectionString As String = "Data Source=localhost\SQLSERVER2008;Initial Catalog=Master; User ID=SA; Password='123123'; MultipleActiveResultSets=false; Connect Timeout=15;Encrypt=False;Packet Size=4096;"

如何检查SQL Server中是否存在数据库？

7 个答案: