如何 select 基于列值的值？

Question

Suppose, Member table has a column named Contact

If Contact has value, Then Type = 1 Otherwise, Type will be blank

What will be the SQL to retrieve Contact and Type

Answer 1

You can use case statement :

SELECT contact, CASE WHEN contact IS NOT NULL THEN 1 AS type
FROM membertable

Answer 2

You can use IIF() function which is introduced and supported after SQL Server 2012.

Syntax:

IIF (boolean_expression, true_value, false_value)

Use:

SELECT concat,  IIF(COALESCE(contact, '') != '', '1', '') AS [type]
FROM Member

Answer 3

Just use a case in your query to generate the type column.

SELECT 
    contact,
    CASE
       WHEN contact IS NOT NULL then 1
       ELSE ''
    END as type
FROM Member