Concatenate two columns based on condition in SQL Server

Hi Makumbi,

Use CASE statement with SUBSTRING function.

Please refer below sample query.

SQL

CREATE TABLE #Books
(
    [Call] VARCHAR(50),
    [BookName] VARCHAR(200),
    [Author] VARCHAR(50)
)
INSERT INTO #Books VALUES('298.5', 'INTRODUCATION TO COMPUTER', 'MUKASA')
INSERT INTO #Books VALUES('500', 'CARTOONS MADE EASY', 'LUBEGA')
INSERT INTO #Books VALUES('632.5','INTRODUCATION TO READING','')
 
SELECT CASE WHEN [Author] = '' THEN [Call] + SUBSTRING([BookName],1,3) 
		ELSE [Call] + SUBSTRING([Author],1,3) END AS [Call], [BookName], [Author]
FROM #Books

DROP TABLE #Books

Output