How can I write a computed column specification in SQL

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I cannot get a Computed Column Specification to work. I have a SQL table named Customers. In Customers the field CustomerID is the primary key and is defined as int. I want to define another field name AccountNumber that has a computed value 'TBS-' followed by the CustomerID converted to a string. Ex: TBS-12345.

What am I doing wrong?

What I have tried:

Here is my last attempt:

SQL

AccountNumber
Computed Column Specification

 (Formula)           (isnull('TBS-'+ CONVERT (VARCHAR(10), CustomerID))) 
 Is Persisted        YES

Posted 17-Mar-22 18:38pm

Member 13694735

Updated 17-Mar-22 21:39pm

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2 solutions

Solution 1

ISNULL takes two parameters: SQL Server ISNULL() Function[^]
It works for me:

SQL

USE [Testing]
GO

/****** Object:  Table [dbo].[MyTable]    Script Date: 18/03/2022 07:02:11 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[MyTable](
	[ID] [int] NOT NULL,
	[Text] [nchar](3) NOT NULL,
	[SerialNo]  AS (isnull([Text]+right('00000'+CONVERT([varchar](5),[ID],(0)),(5)),'????????')),
 CONSTRAINT [PK_MyTable] PRIMARY KEY CLUSTERED 
(
	[ID] 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

Posted 17-Mar-22 21:03pm

OriginalGriff

Comments

CHill60 18-Mar-22 10:53am

I'm guessing the OP failed to use the correct tag on their question. IsNull in MySQL only takes 1 parameter - MySQL ISNULL() Function[^]. They should perhaps have used IFNULL. Gotta love these subtle differences - pointless differences imho

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M Imran Ansari · Accepted Answer · 2022-03-17T21:39:00

Solution 2

Try the following query to add computed column, change length of column accordingly:

SQL

ALTER Table Customers DROP COLUMN AccountNumber  
ALTER TABLE Customers ADD AccountNumber AS (('TBS-'+CONVERT([NVARCHAR](20),[CustomerID]))) PERSISTED

Posted 17-Mar-22 21:39pm

M Imran Ansari

Updated 17-Mar-22 21:40pm