How to lookup index

Question

I'm very new to SQL Server and especially relational data so the question I have is very complex for me, but it's something I've been tasked with. I have a small database acting as an infrastructure inventory into which I'm importing data. The database has
a table called 'vcenters' storing all vcenters and the primary key from this links to the foreign key in several other related tables (e.g. hosts, VMs, Clusters).
CREATE TABLE [dbo].[vcenters](
[vCenterID] [int] NOT NULL,
[vCenterName] [varchar](20) NOT NULL,
[CustomerID] [varchar](10) NOT NULL,
CONSTRAINT [PK_vcenters] PRIMARY KEY CLUSTERED
[vCenterID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[vcenters] WITH CHECK ADD CONSTRAINT [FK_vcenters_Customers] FOREIGN KEY([CustomerID])
REFERENCES [dbo].[Customers] ([CustomerID])
GO
So the vcenters table contains an numeric index field which is auto-incremented each time data is inserted (1,2,3 etc) and a name field. When I go to import the name into one of the other linked tables I instead need to look up the index from the vcenters
table and insert the numeric value but I don't know how to do this?
CREATE TABLE [dbo].[Hosts](
[HostID] [int] NOT NULL,
[HostName] [varchar](25) NOT NULL,
[vCenterID] [int] NOT NULL,
CONSTRAINT [PK_Hosts_1] PRIMARY KEY CLUSTERED
[HostID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Hosts] WITH CHECK ADD CONSTRAINT [FK_Hosts_vcenters] FOREIGN KEY([vCenterID])
REFERENCES [dbo].[vcenters] ([vCenterID])
GO
I understand inner joins but if anyone could help with this then I'd appreciate it. If I'm not making myself clear then please say where and I'll elaborate. Oh, and I'm using SQL Server Express 2014 (as a testbed).
Thanks in advance
Adam

Answer 1

You never mentioned what your source is but if you are hand writing inserts or generating them you could do something like this.
INSERT INTO Hosts (HostName, vCenterID)
VALUES ('MyName',(Select vCenterID from vcenters WHERE vCenterName = 'yourName'))
This does make the assumption that vCenterName is a unique field, to be sure of it I would but a unique index on this field on the table. Also your DDL is missing the key word IDENTITY after your primary key columns, this lets Sql Server auto increment the
id with each new record and assign it as the value. It is probably a good idea to use this for Hosts as well.
CREATE TABLE [dbo].[vcenters](
[vCenterID] [int] IDENTITY NOT NULL,
[vCenterName] [varchar](20) NOT NULL,
-- additional columns
CONSTRAINT [PK_vcenters] PRIMARY KEY CLUSTERED
[vCenterID] ASC
) ON [PRIMARY]
) ON [PRIMARY]
GO
-- unique constraint on vcentername
CREATE UNIQUE NONCLUSTERED INDEX [IX_vcenters_vecenterName] ON [dbo].[vcenters]
[vCenterName] ASC
GO
-Igor