So, the situation is this: I need to check if there is a desired value ("abcd") in the table.

If there is no value, you need to receive a message (using SELECT), for example, this: "value abcd is missing".

How can this be done using SQL?

    2 answers 2

    Two 100% working options:

    True implementation proposed by a colleague with my comments:

    SELECT CASE WHEN EXISTS (SELECT TOP (1) 1 FROM [Table] WHERE [field] = 'abcd') THEN 'EXISTS' ELSE 'value abcd is missing' END

    The second option:

     IF (SELECT COUNT(1) FROM [Table] where [field]='abcd')>0 BEGIN SELECT 'EXISTS' END ELSE BEGIN SELECT 'value abcd is missing' END

    IF Through EXISTS :

     IF EXISTS (SELECT TOP (1) 1 FROM [Table] where field='abcd') BEGIN SELECT 'EXISTS' END ELSE BEGIN SELECT 'value abcd is missing' END

      This, for example, should work in MS SQL:

       SELECT CASE WHEN EXISTS(SELECT TOP 1 1 FROM Table where field='abcd')=1 THEN 'EXISTS' ELSE 'value abcd is missing' END

      In theory, in many other DBMS this should work.

      You can still do the same through the IF ELSE.

      • With the syntax of trouble, it is necessary to remove either EXISTS, or = 1 - Nick Proskuryakov