如何检查特定属性的元素是否存在于列中？

Question

I have been given a question, where I have to Write a TSQL function that will check for the presence of department number in department table.

Here are the records present in the DEPARTMENT table:-

DINT        DNAME                MGRSSN      MGRSTARTDATE TOTAL_SALARY
----------- -------------------- ----------- ------------ ------------
1           Headquarters         888665555   1981-06-19   55000
4           Administration       987654321   1995-01-01   98000
5           Research             333445555   1988-05-22   136000

So, if I pass 1 as a parameter, it should return "YES" because DINT = 1 exists in the table and if I pass 9 as a parameter, it should return "NO".

I don't really know how to approach this question. I tried figuring out how to use BIT in SQL SERVER but did not arrive at anything. The function should consist of one parameter, that is the DEPARTMENT NUMBER which can be denoted as DNO.

I just want this function to return "YES" if the department number is present in the department table, else return "NO".

Answer 1

SQL DEMO

CREATE FUNCTION existDept
 (
 @dno AS integer
 )
RETURNS VARCHAR(MAX)
AS
BEGIN
    DECLARE @return_value VARCHAR(MAX);
    SET @return_value = 'NO';

    SELECT @return_value = 'YES'
    FROM dept
    WHERE department_id = @dno;

    RETURN @return_value;
END;

TEST

SELECT dbo.existDept(1);
SELECT dbo.existDept(7);

Answer 2

In one SQL query:

select IIF((select count(*) FROM DEPARTMENT where DINT=@yourParam) > 0, 'Yes', 'No') as Result

You need to replace @yourParam with the correct parameter.

Answer 3

Please try with this.

Declare @dint as int
set @dint='1'
SELECT case when count(DINT)>0 then 'Yes' else 'No' end FROM DEPARTMENT 
where DINT=@dint;

Answer 4

row count https://www.php.net/manual/en/pdostatement.rowcount.php

example:

<?php
$sql = "SELECT COUNT(*) FROM fruit WHERE calories > 100";
if ($res = $conn->query($sql)) {

    /* Check the number of rows that match the SELECT statement */
    if ($res->fetchColumn() > 0) {

        /* Issue the real SELECT statement and work with the results */
        $sql = "SELECT name FROM fruit WHERE calories > 100";

        foreach ($conn->query($sql) as $row) {
            print "Name: " .  $row['NAME'] . "\n";
        }
    }
    /* No rows matched -- do something else */
    else {
        print "No rows matched the query.";
    }
}

$res = null;
$conn = null;
?>

It's just a example, but it can be done with multiple ways, post your code so it will be better implemented