How to do inner or sub-query for the same object in SOQL

Question

I'm facing an issue to select the value from the same object. I provided the query below.

I'm migrating a Java J2EE application to Salesforce, the below query works in my SQL.
I'm trying to do the same in SOQL, but it doesn't work.

 SELECT DATA1__c, TEXT__c 
     FROM PARAMETERS__c 
     WHERE ( (TYPE__c = 'ADMINISTRATEUR') 
         AND (KEY1__c LIKE 'MONTAGE%') (AND KEY2__c = '')) 
         AND (DATA1__c 
                  IN (SELECT KEY1__c 
                      FROM Parameters__c 
                      WHERE TYPE__c = 'PERE_TECHNIQUE'))

In the above query I need to take the value where TYPE is based on 'TECHNIQUE' where KEY1__c should be matched to DATA1__c from the outer query.

The query is very similar to this example

 SELECT Id 
     FROM Idea 
     WHERE ((Idea.Title LIKE 'Vacation%') 
         AND (CreatedDate > YESTERDAY)  
         AND (Id IN (SELECT ParentId 
                     FROM Vote 
                     WHERE CreatedById = '005x0000000sMgYAAU'))

The only difference is that IN clause is used with a different object. In my query I'm trying to use IN clause from the same object parameters.

Kindly let me know in case of any further clarifications.

Answer 1

try the following

List<String> pereTechniqueParams = new List<String>();
for (String key: 
          [SELECT KEY1__c FROM Parameters__c WHERE TYPE__c = 'PERE_TECHNIQUE']) {
    pereTechniqueParams.add(key.KEY1__c);
}

List<Parameters__c> params = [SELECT DATA1__c, TEXT__c 
                                  FROM PARAMETERS__c 
                                  WHERE (TYPE__c = 'ADMINISTRATEUR' 
                                         AND KEY1__c LIKE 'MONTAGE%' 
                                         AND KEY2__c = '') 
                                      AND DATA1__c IN:pereTechniqueParams];

UPDATE:

for (Parameters__c key1 : [SELECT KEY1__c 
                    FROM Parameters__c WHERE TYPE__c = 'PERE_TECHNIQUE']) {
    pereTechniqueParams.add(key1.KEY1__c);
} 

Don't use String use Parameters__c

public class LookUpController {
    public List<Parameters__c> getParamters() {
        List<String> pereTechniqueParams = new List<String>();
        for (Parameters__c key1 : [SELECT KEY1__c 
                            FROM Parameters__c WHERE TYPE__c = 'PERE_TECHNIQUE']) {
            pereTechniqueParams.add(key1.KEY1__c);
        } 
        List<Parameters__c> params = [SELECT DATA1__c, TEXT__c 
                               FROM PARAMETERS__c 
                               WHERE TYPE__c = 'ADMINISTRATEUR' 
                                   AND KEY1__c LIKE 'MONTAGE%' 
                                   AND KEY2__c = '' 
                                   AND Data1__c IN: pereTechniqueParams];
        return params;
    }
}