sql case and condition code example

Example 1: sql CASE

/*CASE statements are used to create different outputs and is 
  used by SQL as a way to handle if-then logic.*/
  
  SELECT column_name,
    CASE 
      WHEN condition THEN 'Result_1'
      WHEN condition THEN 'Result_2'
      ELSE 'Result_3'
    END
  FROM table_name;

Example 2: case when with count and combining similar values in sql

SELECT 
    data.id,
    data.lastname,
    data.firstname,
    SUM(data.WebData) AS WebData,
    SUM(data.InternalData) AS InternalData,
    SUM(data.countid) AS Countid
FROM
    (
       SELECT id,lastname,
              firstname,datasource,
              CASE WHEN Datasource = 'Web' THEN Count(Datasource) ELSE 0 END WebData,
              CASE WHEN Datasource = 'Internal' THEN Count(Datasource)ELSE 0 END InternalData,
             count(id) AS Countid

        FROM Table
        GROUP BY
                 id,lastname,firstname,datasource
     ) AS data
GROUP BY 
    data.id,data.firstname,data.lastname