Question: I have gone through almost all posts for this error. But i was unable for figure out the issue.
I have tried to change build.gradle repositories to mavenCentral() and have also tried make changes in app.gradle. I just though of adding volley into my app, from then the sync is getting failed.
I have also tried file->Invalidate caches/Restart.

I feel there is some problem with getDefaultProgaurdFile. as I can see it is underlined.
Please help me on this.
Thanks

```
                apply plugin: 'com.android.application'
            android {
             compileSdkVersion 23
             buildToolsVersion "23.0.2"
             defaultConfig {
              applicationId "com.six30labs.cms"
              minSdkVersion 15
              targetSdkVersion 19
              versionCode 1
              versionName "1.0"
             }
             buildTypes {
             release {
             minifyEnabled false
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
              }
             }
            }

```

<http://postimg.org/image/4kv7qh7cr/>

<http://postimg.org/image/azlbyum2b/>

Answer: 
```
insert into table_a (f1, f2, f3, f4, f5, f6)
select f1, f2, f3, f4, f5, f6
from (
    (
        select $1, $2, $3, f4, f5, f2, 1
        from table_a
        where <conditionals>
        order by <ordering>
        limit 1
    ) s
    union all
    select $1, $2, $3, '', '', null, 2
) s (f1, f2, f3, f4, f5, f6, o)
order by o
limit 1

```
Just another way if you want to use default value from table DDL instead of hardcoded in the query:

```
WITH t AS (
  INSERT INTO table_a (f1, f2, f3, f4, f5, f6)
  SELECT               $1, $2, $3, f4, f5, f2
  FROM        table_a
  WHERE       <conditionals>
  ORDER BY    <ordering>
  LIMIT       1
  RETURNING *) -- This query will return inserted values
INSERT INTO table_a (f1, f2, f3)
SELECT $1, $2, $3 WHERE (SELECT count(*) FROM t) = 0; -- Insert if no insertion was happened at WITH clause

```