The SQL From clause is the source of a rowset to be operated upon in a Data Manipulation Language (DML) statement. From clauses are very common, and will provide the rowset to be exposed through a Select statement, the source of values in an Update statement, and the target rows to be deleted in a Delete statement. [1]
FROM
is an SQL reserved word in the SQL standard. [2]
The FROM
clause is used in conjunction with SQL statements, and takes the following general form:
SQL-DML-Statement FROM table_name WHERE predicate
The From clause can generally be anything that returns a rowset, a table, view, function, or system-provided information like the Information Schema, which is typically running proprietary commands and returning the information in a table form.[3]