SQL - Show records which meet 2 or more of multiple conditions

Question

I have a MySQL table of many records. I am trying to find a way to show the records which meet more than one condition of a query. For example, if I had this table.

TABLE NAME: DATA

ID   contactid  flag        flag_type 
-----------------------------------
1     99         Volunteer   1 
2     99         Uploaded    2 
3    100         Via Import  3 
4    100         Volunteer   1  
5    100         Uploaded    2

with conditions such as:

WHERE (ID > 2) OR (flag = 'Uploaded') OR (flag_type = 1) ..etc..

The output would be where IDs 4 & 5 only would be returned.

Answer 1

You can count the number of conditions in MySQL and use this value:

where ((id > 2) +
       (flag = 'Uploaded') +
       (flag_type = 1)
      ) > 1

A boolean value of "true" is treated as 1 AND "false" is treated as 0. So, by adding up the values, you get the number of conditions that are met.

Often, you do this in an order by, to get the most matching first:

where id > 2 or flag = 'Uploaded' or flag_type = 1
order by ((id > 2) +
          (flag = 'Uploaded') +
          (flag_type = 1)
         ) desc;