The query languages are used to access data for data manipulation. There are two query languages in the Force.com platform:
Salesforce.com Object Query Language (SOQL)
Salesforce.com Object Search Language (SOSL)
Both of these languages are used to retrieve a set of data from the Force.com platform.
We assume that you are already familiar with query language such as SQL, which is the universal standard for interacting with relational databases. In the Force.com platform, we considered the data repository of the Force.com platform as the relational database. Therefore, we use SOQL instead of SQL for data-retrieving purposes. There are similarities as well as differences in SOQL and SQL.