Meaning of WebSql query

Question

I'm working on port code from WebSQL to IndexedDb. I'm stuck in the following query,

SELECT ad.* FROM AdminUserDetails as ad inner join CustomerDetails pd on 
pd.CaseManagerId=ad.AdminUserId or pd.CareCoordinatorId=ad.AdminUserId WHERE  
pd.CustomerNo='" + CustomerNo "'"

I'm not able to understand the complete above query and how do I convert the above code into IndexedDb.